Automatic rearview mirror system using a photosensor array

A system apparatus, structure and method for controlling a plurality of variable reflectance mirrors (or mirror segments), including a rearview mirror and side view mirrors, which change their reflectance level in response to a plurality of drive voltages applied thereto, for an automotive vehicle. The system includes a light sensing device and a control circuit formed as a single VLSI CMOS circuit. The light sensing device comprises a photosensor array having a field of view encompassing a rear window area and at least a portion of at least one side window area of the vehicle. The logic and control circuit determines a background light signal from photosensor element signals generated by the photosensor elements in the photosensor array indicative of light levels incident on the photosensor elements. The circuit also determines a peak light signal in three different zones or sub-arrays of the photosensor array. The zones or sub-arrays may correspond to three mirrors or mirror segments. The peak light signals in each of the zones and a common background light signal are used to determine independent and separate control signals, which are then output to separate mirror drive circuits for independently controlling the reflectance level of the rearview mirror and the left and right side view mirrors, or alternatively the segments of a mirror.
Description
This application is a divisional of application Ser. No. 08/023,918 filed Feb. 26, 1993, now U.S. Pat. No. 5,550,677.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an automatic rearview mirror system for automotive vehicles which automatically changes reflectance level in response to glare causing light, and more particularly relates to an improved automatic rearview mirror system using only a rearwardly facing sensor.
2. Description of Related Art
Automatic rearview mirrors and mirror systems have been devised for varying the reflectance level of a variable reflectance rearview mirror by reducing the reflectance automatically in response to annoying glare light, as seen rearwardly of the rearview mirror or mirrors by a driver of the vehicle, and by increasing automatically the reflectance to a normal or maximum reflectance level when the annoying glare light subsides. These automatic mirrors have been changed over the years in an effort to improve their performance characteristics and associated level of glare protection.
Early automatic rearview mirrors used a rearwardly facing sensor and control circuit to change mirror reflectance. One example of such a "single-sensor" type mirror is described in U.S. Pat. No. 4,266,856. In these prior art single-sensor type mirrors, the rear glare light was incident on a rearwardly facing sensor or photocell, such as a photodiode, photoresistor or phototransistor. These mirrors suffered from various problems, however, including the problem that these mirrors would become increasingly sensitive and even "lock-up" in their minimum reflectance level or state as the driver encountered significantly higher light levels in town or city driving. This required the driver to repeatedly adjust the mirror's sensitivity control to prevent such problems.
To overcome the problems of single-sensor type mirrors, a non-rearwardly facing photocell for sensing "ambient" light was added. It was believed that the desired reflectance necessary to relieve the driver from glare depended not only on glare light but also on ambient light. Accordingly, these "two-sensor" type mirrors used two separate photocells, one generally facing rearwardly and one generally facing forwardly (or other non-rearwardly facing direction) of the mirror or vehicle. The signals from these two photocells were then compared in some fashion, and when, for example, the glare light from the rear was comparatively high with respect to the "ambient" light, a control circuit would apply a control signal to reduce mirror reflectance. Some examples are described in German Laid-Open Patent No. 3,041,692; Japanese Laid-Open Patent No. 58-19941; and U.S. Pat. Nos. 3,601,614; 3,612,666; 3,680,951; 3,746,430; 4,443,057; 4,580,875; 4,690,508; and 4,917,477. In many of these prior art automatic rearview mirrors, light generally forward of the mirror or vehicle was incident on the second photocell.
These arrangements, however, also had problems. In some of these mirrors the forwardly facing or "ambient" light sensor was inaccurate because it did not correctly measure ambient light levels since it did not include light generally rearward of the mirror or vehicle. Some examples include the devices described in U.S. Pat. Nos. 4,443,057 and 4,917,477. Other prior art devices overcame these deficiencies by providing a control circuit which correctly measured ambient light as a combination of both the forward and rear light levels. Examples of this significantly different approach are described in U.S. Pat. Nos. 4,793,690 and 4,886,960.
The prior art two-sensor type systems generally provided improved performance over prior art single-sensor type systems but were also more complex and costly. In part, this was because using separate forwardly and rearwardly facing photocells required that the performance characteristics of the two separate photocells, such as photoresistors, be matched appropriately to ensure consistent performance under various operating conditions. Matching photocells such as photoresistors, however, generally involves complex, expensive and time consuming operations and procedures.
Both the prior art single-sensor and two-sensor type mirrors presented additional problems when they were also used to control the exterior side view mirrors. This is because such prior art systems used a common control or drive signal to change the reflectance level of both the interior rearview mirror and the exterior left and/or right side view mirrors by substantially the same amount. In U.S. Pat. No. 4,669,826, for example, a single-sensor type mirror system used two rearwardly facing photodiodes to control both an interior rearview mirror and the left and/or right side view mirrors based on the direction of incident light from the rear. Another example includes the two-sensor type system described in U.S. Pat. No. 4,917,477.
In rearview mirror systems, however, each of the interior rearview and exterior side view mirrors may reflect different source light levels. More specifically, the inside rearview mirror, left side view mirror and right side view mirror each enable the driver to view a different portion or zone of the total rearward area. Of course, there may be some overlap of the image information contained in each of the three zones. The situation is further complicated with multi-lane traffic because each of the mirrors reflects different light levels caused by the headlights of the vehicles which are following, passing or being passed. As a result, in the prior art systems, when the reflectance level of the interior rearview mirror was reduced to decrease the glare of headlights reflected therein, the reflectance level of the exterior left and right side view mirrors was also reduced by substantially the same amount, even though, for example, the side view mirrors might not be reflecting the same level of glare light, if any. Accordingly, rear vision in the exterior left and right side view mirrors could be improperly reduced.
Other prior art two-sensor type systems used a common ambient light sensor and several rearwardly facing sensors, one for each of the mirrors. An example is the alternate system also described in U.S. Pat. No. 4,917,477. This approach is not satisfactory, however, because it reduces system reliability and increases complexity and cost.
Finally, some prior anti-glare mirrors used several sensors to control the segments of a variable reflectance mirror. One example is disclosed in U.S. Pat. No. 4,632,509, which discloses a single-sensor type mirror using three rearwardly facing photocells to control three mirror segments depending on the direction of incident light from the rear. See also U.S. Pat. No. 4,697,883. These prior mirror systems generally have the same problems as the other single-sensor type mirrors. Some other anti-glare mirrors are generally disclosed in U.S. Pat. Nos. 3,986,022; 4,614,415; and 4,672,457.
Consequently, there is a need for an automatic rearview mirror system for an automotive vehicle having improved reliability and low cost, which accurately determines or otherwise discriminates light levels that the driver will experience as glare without the need for a separate forwardly facing photocell. In addition, as noted above, there is also a need for an automatic rearview mirror system of high reliability and low cost, which accurately determines light levels that the driver will experience as glare, and which can control independently the reflectance of a plurality of mirrors according to the light levels actually reflected by each of the rearview and exterior side view mirrors without the need for additional and separate rearwardly facing photocells. There is also a need for an automatic rearview mirror system that can independently control the segments of a variable reflectance mirror while accurately determining light levels that the driver will experience as glare in each segment of the mirror without the need for additional and separate forwardly and rearwardly facing photocells.

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Color controller integrates RGB photosensor

Avago Technologies has announced a color controller with an integrated color photosensor for backlighting LCDs, touted to be the industry's first such product. According to the company, the new ADJD-J823 enables more accurate and consistent RGB LED backlighting and richer colors than conventional technology. This solution is suitable for use in digital cameras, cell phones, PDAs, portable DVD players and display screens measuring 7 inches diagonal or smaller.
The device has a small footprint and low profile that allows it to easily fit into portable LCD devices where board space is limited, Avago said. The 5-by-5-by-0.75mm illumination and color management (ICM) device operates at voltages as low as 2.5V.
The new device is a CMOS mixed-signal IC with integrated RGB photosensors designed to be the closed loop optical feedback device of an RGB LED-based backlighting system. It also has a wide gain control and uses an algorithm to automatically select the optimum gain.
A typical system consists of an array of RGB LEDs, LED drivers and the color controller. The device samples the light output from the RGB LED array, processes the color information and adjusts the light output from the RGB LEDs until the target color is achieved. To do this, the device integrates an RGB photosensor array, an ADC front-end, a color data processing logic core and a high-resolution 12bit PWM output generator. By employing a feedback system and the color controller, the light output produced by the LED array maintains its color over time and temperature.
"By integrating the sensor and controller into one package, we are expanding the benefits of color management to the growing array of applications using color LCD screens in smaller consumer electronics," said Lee Soo Ghee, vice president and general manager for Avago's Optoelectronic Products Division.
Avago said the use of LED backlighting with the company's ICM control in LCD TVs has been proven to offer 25 percent richer colors than conventional cold cathode fluorescent lamp (CCFL) backlighting. In addition, LED backlighting totally eliminates the traces of mercury found in CCFLs to meet European Union RoHS mandates, the company said.

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InGaP/GaAs heterojunction photosensor powered by an on-chip GaAs solar cell for energy harvesting

In this study, an InGaP/GaAs heterojunction phototransistor (HPT) and a GaAs solar cell were monolithically integrated into an HPT epitaxial wafer, and the battery-free operation of the HPT was demonstrated for energy harvesting. Although the thickness and doping condition of the layers were optimized for the HPT performance, but not for the solar cell performance, the obtained short-circuit current was high enough to operate the InGaP/GaAs HPT in a two-terminal (2T) configuration. A collector photocurrent of 0.63 mA was obtained when the energy-harvesting InGaP/GaAs 2T-HPT was exposed to white light with a power density of 35 mW/cm², and it linearly increased with the power density. For a potential application of the energy-harvesting InGaP/GaAs HPT as a photosensor in space, the device was irradiated with electrons of 1 MeV energy and 10¹⁵ cm⁻² fluence. No significant degradation of the fabricated energy-harvesting 2T-HPT after the high-energy electron irradiation guarantees its battery-free operation in space.

A heterojunction phototransistor (HPT) is more attractive as a photosensor than a photodiode because of its high photoresponse even at low bias voltage and immunity from avalanche noise. In particular, the GaAs-based HPT with an AlGaAs emitter demonstrated a high performance. Recently, the InGaP emitter has replaced the AlGaAs emitter in the AlGaAs/GaAs HPT owing to its superior material properties. The photosensor may be widely used in space, where it needs to be operated without a battery. An HPT has a process compatibility with a heterojunction bipolar transistor (HBT) for the fabrication of monolithically integrated photoreceivers. The InGaP/GaAs HPT also has good compatibility with the GaAs heteroface solar cell for a battery-free operation. Solar cells made of III–V compound semiconductors have been developed and used in space owing to their high conversion efficiency, lower temperature coefficient, and superior radiation resistance. The significant potential of high-efficiency GaAs heteroface solar cells for space applications has been extensively investigated by many researchers.Compared with Si, which has been widely used as a material of terrestrial solar cells, III–V compound semiconductors have a superior radiation resistance for the same electron energy and fluence. In particular, the InGaP solar cells demonstrated a radiation resistance superior to that of GaAs solar cells. Since the migration energy of radiation-induced defects and the activation energy of defect annealing in InGaP are lower than those in GaAs, InGaP has a higher radiation resistance than GaAs. In this study, radiation resistant InGaP was used as a window layer in a GaAs heteroface solar cell.
In space, high-energy electron or particle irradiation often induces a significant degradation of the performance of semiconductor devices. Since the battery-free operation of an InGaP/GaAs HPT monolithically integrated with a GaAs solar cell is also proposed for use in space in this paper, the effects of high-energy electron irradiation on the fabricated energy-harvesting HPTs were studied by 1 MeV electron irradiation.

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Low-cost miniaturized UV photosensor for direct measurement of DNA concentration

Highly sensitive measurement of DNA concentration on portable, easy-to-use, low-cost miniaturized equipments without sample waste is challenging.
The DNA peak optical absorbance at λ=260 nm is a well-known property already used in the spectrometric measurement of DNA concentration. Existing apparatus are large-sized, expensive and require a manipulation of DNA. In the current work, a low-power, suitable and miniaturized photosensor aiming at a sensitive and direct measurement of DNA concentration has been designed. Direct measurement, i.e. without sample manipulation, implies UV transmission through the translucid tube wall from the closed tube containing the DNA sample in solution.
To allow measurements at such low wavelengths, we designed and fabricated photodiodes in SOI technology to ensure a high responsivity in the UV range. Measurements of the photodevice confirmed its responsivity spectrum and magnitudes. These fully integrable photodiodes, fabricated in SOI CMOS technology, can be coupled to a complete signal processing microsystem.
Direct measurements at 280 nm optical wavelength of serially diluted DNA within a closed tube (range: 40 pg/μL to 400 ng/μL in a volume of 45 μL) generated a monotonic relation between the DNA concentration and the mean of the diode photocurrent induced by light transmission through DNA solution and tube container. Absorbance of the incident UV ray was inversely proportional to DNA concentration. The photosensor compared favorably with other DNA quantitative methods (spectrophotometry, fluorometry, real-time PCR) in terms of sensitivity.
Originalities of this work are the use of a thin-film SOI photosensor, the low-cost, portable and adaptable system and the potential of the device for direct measurement of nucleic acid concentration within tube containers without sample manipulation or waste.

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Apple could use curved photosensors to product smaller iPhone cameras

A new Apple patent reveals the Cupertino company could soon employ curved photosensors to create smaller iPhone cameras that capture better photos. The design could help Apple in its mission to make future smartphones even thinner.
Published by the U.S. Patent and Trademark Office this week, “Small form factor high-resolution camera” describes a cutting-edge mobile camera module that uses complex optics to deliver a more compact footprint and even better performance.
Apple explains how the sensor could refract light through a trio of special lenses onto a concave surface, resulting in a sharp, low-distortion image. The company also notes that the curved array limits diffraction, allowing the use of a smaller sensor with smaller pixels.
“To correct for diffraction and visual aberrations that propagate within miniature cameras, the proposed lens system includes three lenses, two of which are convex or substantially convex,” explains AppleInsider. “A third meniscus lens, or a lens with opposing convex and concave surfaces, is situated between the first two lens elements and the spherical photosensor.”
The design does have its limitations, however, such as barrel distortion. Apple describes how it might use software to correct unwanted effects like this.
Such sensors could allow Apple to make the iPhone thinner, or ensure future sensors sit flush with the handset’s case — rather than protruding out of it like they do with iPhone 6 and iPhone 6s. It could also lead to better cameras in the iPad, and even cameras in devices like Apple Watch.
But as always, Apple patents are never a guarantee of things to come, so this particular invention may never see the light of day.
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Toshiba Matsushita Display Develops Photosensor Touch-Panel

Toshiba Matsushita Display Technology Co., Ltd. (TMD) has developed an LCD panel that enables finger-touch input using photosensors under a range of light conditions from dark indoor to bright outdoor. Through enhanced sensitivity of the photosensors integrated onto the LCD panel's glass substrate and optimized signal processing functions, the panel detects reflection from a finger using backlight in dark indoor and finger shadows using external light in bright outdoor.

The prototyped panel is a transmissive LCD panel using a 2.8-inch (7.1 cm diagonal) WQVGA (400 x 240 pixels) resolution, low-temperature polycrystalline Si (p-Si) TFT with approximately 65,000 display colors. The range of ambient light intensity, in which finger-touch input is available, extends from 0 to 100,000 lx.

The panel has become able to recognize finger-touch input in a wide range of light intensity by switching its recognition modes between finger shadows using external light and finger reflections using its built-in backlight depending on the situation. The panel not only recognizes finger shadows but also supports input using an optic pen. TMD will present this panel at the Flat Panel Display International (Display 2007) show to be held at Tokyo Big Sight from April 11 to 13.

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Beam extrapolation and photosensor testing for the T2K experiment

Our understanding of the physics of neutrino oscillations has evolved rapidly over the past decade or so, with results from the SNO, Super-K, MINOS and CHOOZ experiments, among others, producing results favouring a three-neutrino mixing model, and significantly constraining the parameter space for the mixing.

There are still several important questions to be answered however: we do not know whether theta_13 is non-zero, or whether (sin^2 (2*theta_23)) is maximal; also, we do not know the sign of the mass splitting Delta M^2, or whether CP-violation occurs in the lepton sector. The latter is possibly the most exciting of all - leptonic CP-violation is a requirement for leptogenesis, and could therefore indicate a solution to the matter-antimatter asymmetry problem in cosmology. The T2K long-baseline neutrino experiment is one of a new generation of neutrino projects, which will make more precise measurements of theta_13 and theta_23 than has been achieved by previous experiments. It uses the Super-K water Cerenkov detector at Kamioka as a far detector, and also has a suite of new near detectors.

These are largely scintillator-based, but use a novel photosensor, the silicon photomultiplier (SiPM), for light readout. T2K has been leading the effort understand and model these new sensors, and the present work will describe the current state-of-the-art in device characterisation, and also the effort to ensure the quality of the devices installed in the calorimeter of the ND280 near detector. An important part of a long-baseline analysis is the extrapolation of the neutrino flux measured at the near detector to predict that at the far detector. Methods to do this have been developed by previous experiments; however T2K uses an innovative configuration whereby the main detectors are displaced from the neutrino beam centre, removing much of the high-energy tail in the neutrino flux to reduce backgrounds from non-quasielastic events. This thesis evaluates the effectiveness of two extrapolation techniques, used by previous experiments, for the T2K configuration.

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Graphene photosensor integrated into computer chip

Today, most information is transmitted by light – for example in optical fibres. Computer chips, however, work electronically. Somewhere between the optical data highway and the electronic chips, photons have to be converted into electrons using light-detectors.

Scientists at the Vienna University of Technology have integrated a graphene photosensor with a standard silicon chip. The hybrid device can transform light of all important telecommunications frequencies into electrical signals. The scientific results have now been published in the journal Nature Photonics.

Optical fiber transmission uses wavelengths that are in the near-infrared portion of the spectrum. Typical wavelengths are 850nm, 1310nm, and 1550nm. Both lasers and LEDs are used as transmission sources; lasers usually for 1310 or 1550nm single-mode applications while LEDs typically for 850nm or 1300nm multimode applications.

Both academia and the industry are placing high hopes in graphene for many different applications. Two years ago, the team of Thomas Müller (Institute of Photonics, Vienna University of Technology) demonstrated that graphene is ideally suited to convert light into electrical current.

Müller commented, “There are many materials that can transform light into electrical signals, but graphene allows for a particularly fast conversion. So wherever large amounts of data are to be transmitted in a short period of time, graphene will in the future probably be the material of choice.”

Significant development

The researchers had to come a long way from the basic proof of what the material can do to actually using it in a chip – but now they have succeeded. The Viennese team worked together with researchers from the Johannes Kepler University in Linz.

Müller added, “A narrow waveguide with a diameter of about 200 by 500 nanometers carries the optical signal to the graphene layer. There, the light is converted into an electrical signal, which can then be processed in the chip. There have already been attempts to integrate photodetectors made of other materials, such as germanium, directly into a chip. However, these materials can only process light of a specific wavelength range.”

The researchers say that they can show that graphene can convert all wavelengths which are used in telecommunications equally well. The graphene photodetector is not only extremely fast, it can also be built in a particularly compact way: for example, 20 000 such detectors could fit onto a single chip with a surface area of 1cm². Theoretically, the chip could be supplied with data via 20,000 different information channels.

”These technologies are not only important for transmitting data over large distances. Optical data transmission also becomes more and more important for communication within computers”, says Thomas Müller. When large computer clusters work with many processor cores at the same time, a lot of information has to be transferred between the cores. As graphene allows switching between optical and electrical signals very quickly, this data can be exchanged optically. This speeds up the data exchange and requires much less electrical energy.

W The light signal arrives throuth a waveguide (left), in the 2 micrometer wide graphene sheet, electrical current is generated. G 
Graphene - a two dimensional sheet made of carbon atoms - can convert light into electrical current. "CMOS-compatible graphene photodetector covering all optical communication bands", Pospischil et al., Nature Photonics (2013), doi:10.1038/nphoton.2013.240

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More graphene! This time in a broadband photosensor

Singapore--Cameras fitted with a new graphene-based sensor developed at Nanyang Technological University (NTU) will soon be able to take clear and sharp photos in dim conditions, according to NTU.

The sensor is believed to be the first to be able to detect broad-spectrum light from the visible to mid-IR with high photoresponse, says NTU. If so, it would be suitable for use in many types of cameras, including IR cameras, traffic cameras, satellite imaging, and so on.

The graphene sensor is supposedly 1000 times more sensitive to light than current imaging sensors found in today’s cameras and uses ten times less energy, as it operates at lower voltages. When mass produced, graphene sensors are estimated by NTU to cost at least a factor of five less than conventional sensors.

The inventor of the graphene sensor, Wang Qijie, from NTU’s School of Electrical & Electronic Engineering, said it is believed to be the first time that a broad-spectrum, highly photosensitive sensor has been developed using pure graphene.

Nanostructures
His device, made by fabricating a graphene sheet into novel nanostructures, was featured in a paper published this month in Nature Communications. The nanostructures trap electrons, which is the key to achieving high photoresponse in graphene, making it far more effective than the normal CMOS or CCD image sensors, says Wang.

“While designing this sensor, we have kept current manufacturing practices in mind," sys Wang. "This means the industry can, in principle, continue producing camera sensors using the CMOS (complementary metal-oxide-semiconductor) process, which is the prevailing technology used by the majority of factories in the electronics industry. Therefore, manufacturers can easily replace the current base material of photosensors with our new nanostructured graphene material.”

“The performance of our graphene sensor can be further improved (such as the response speed) through nanostructure engineering of graphene, and preliminary results already verified the feasibility of our concept,” Wang adds. Development of the sensor took Wang and his team two years to complete.

Wang has filed a patent through NTU’s Nanyang Innovation and Enterprise Office for his invention. The next step is to work with industry collaborators to develop the graphene sensor into a commercial product.

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iphone 7- No dual camera,but with a single photo sensor

A new 3D drawing of what appears to be a metal case for the iPhone 7 reveals more about the upcoming device and also confirms that the new model will be quite similar in design with the existing one.

Renowned leaker @OnLeaks has posted the sketch on French website NWE, revealing that the upcoming iPhone 7 will have the exact same dimensions as the current 6s model (this is only valid for the standard 4.7-inch version, but the chances are that the Plus models will have the same size too).

Specifically, the iPhone 7 could measure 138.3 x 67.1 mm 5.44 x 2.64 inches), so it’ll be identical to the iPhone 6s – note that we still don’t know how thin the new model will be, but the same report claims that the two models will be similar in this regard too.

So basically, the iPhone 7 and the iPhone 6s will have the same dimensions, but Apple is also preparing some rather minor aesthetic changes on the back of the new model.

No dual camera

As you can see in this drawing, the camera bump is moved slightly closer to the left top corner and this aligns with previous reports indicating that Apple was indeed planning such a change. This pretty much makes it impossible to use a 6s case with the iPhone 7 (as you can do right now between iPhone 6 – 6s and 5s – SE),

But the camera cutout also shows that they’ll be just a single photo sensor, so in case you were hoping for dual cameras, this doesn’t seem to be the case. Previous rumors indicated that a dual-camera setup might be exclusive to the iPhone 7 Plus, so there’s still hope that this upgrade would arrive on the next-generation model, but we won’t be getting it on the 4.7-inch version.

Other than that, the iPhone 6s and the iPhone 7 seem to be like two peas in a pod, but since the debut of the new model is planned for September this year, expect more information on what’s going to be changed to emerge in the coming weeks. Hopefully, the WWDC conference next month will also bring us some news in this regard.

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A highly sensitive and low-noise IR photosensor based on a-SiGe as a sensing and noise filter

The a-SiGe TFT photosensor for embedded touch-screen panels (TSPs) was characterized by comparison with an a-Si sensor.

The photoresponse of an a-SiGe sensor at a 850-nm wavelength was much higher than that of a-Si, indicating that a-SiGe is a strong candidate material for an IR sensor.

In order to increase the signal-to-noise ratio, the incident visible light was filtered by incorporating a bandpass-filter layer. An a-SiGe IR-sensor-embedded LCD panel was successfully demonstrated, showing an excellent multitouch property independent of ambient-light conditions. This technology can be widely used in multifunctional TSPs.

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Amorphous silicon photosensors integrated in microfluidic structures

In this paper we present a compact technological demonstrator including on the same glass substrate an electrowetting-on-dielectrics (EWOD) system, a linear array of amorphous silicon photosensor and a capillary-driven microfluidic channel. The proposed system comprises also a compact modular electronics controlling the digital microfluidics through the USB interface of a computer. The system provides therefore both on-chip detection and microfluidic handling needed for the realization of a ‘true’ Lab-on-Chip.

The geometry of the photosensors has been designed to maximize the radiation impinging on the photosensor and to minimize the inter-site crosstalk, while the fabrication process has been optimized taking into account the compatibility of all the technological steps for the fabrication of the EWOD system, the photosensor array and the microfluidics channels.

As a proof of the successful integration of the different technological steps we demonstrated the ability of the a-Si:H photosensors to detect the presence of a droplet over an EWOD electrode and the effective coupling between the digital and the continuous microfluidics, that can allow for functionalization, immobilization and recognition of biomolecules without external optical devices or microfluidic interconnections.

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Are You Having Problems with your Photo-Sensors?

Just as car washes vary from self serve to rollover to tunnel wash, there are many types of sensors being used to start, stop, measure length, and control the wash and entry/exit doors. However, all sensors are not created equal. There are early warning signs to look for that might indicate a maintenance check-up is in order.
Are the automatic doors operating properly? Are the nozzles turning on and off as needed? Is soap being dispensed after vehicles exit the wash instead of on time? Does snow and ice cause false signals from the photo-eyes?
If your wash equipment and door systems are not functioning correctly, the photo-eyes that signal the wash line's computer system may not be operating properly. We will examine the most common problems that photo-eyes face in the demanding wash environment and the features that you should consider when selecting sensors for your wash. Afterwards, we will review various types of applications in each type of wash and give some "first-aid" tips for your photo-eye sensors.
How many of you have ever experienced fog in your bays so thick that you couldn't see someone standing 10 feet away? This is a very common problem in locations where cooler temperatures during the winter months combined with hot water put extreme demands on your sensors. Most photo-eyes would fail under these circumstances. To compound this problem, add soap, grease and dirty water and you have the makings for a true disaster.
You know the picture. After a week of snow and ice, the sun finally comes out and the temperature rises to create a nice slushy, mud bath for your car. As cars line up at the wash, the last thing the operator needs is for the equipment to stop working. One single day of non-operation means lost profit that you can never recover.
Keeping your car or truck wash equipment in top-notch condition includes checking and replacing defective photo-eyes. Sensors provide the critical signal to the wash computer. Therefore, it is absolutely necessary they operate properly. As the old saying goes, "junk in, junk out." A photo-eye could mean the marginal difference between profit and loss for your wash.
Common Problems
The number one reason for photo-eye failure is contamination. A car wash is ideally the best testing grounds for a photo-eye because of contamination. Practically, no other industry can compare to the wet, hostile environment of the car wash's dirt, steam, ice, snow, soap, film, grease and everyone's "favorite", fog. If a photo-eye can pass this test, you have a winner.
There are some sensor brands of this caliber on the market. They are able to withstand this type of abuse because they do not use a lens to magnify the light to the receiver eye. Lens-less eyes are usually designed as modulated infrared sensors (see figure 2).
The transmitter LED (light emitting diode) is turned on and off, acting as a pulse of light, invisible to the naked eye. The receiver is calibrated to the same frequency of modulation to accept the transmittal signal.
Just as a lighthouse penetrates the fog to warn an approaching ship of danger, the lens-less photo-eye cuts through fog, steam, dirt and grime to ensure your car wash trouble-free service. Relate the photo-eye made with a lens to a pair of glasses. If you walk into the wash wearing glasses, they immediately become fogged up. You must take the glasses off and clean them. This is a perfect example of the wrong photo-eye to use in a car wash. By removing the photo-eye made with a lens you eliminate the step of continual lens cleaning.
Misalignment is another photo-eye problem common to car wash facilities. In some cases, it is possible to judge visually if the eyes are out of alignment at an angle or askew to one another.
When installing photo-eyes at a distance of eight to twelve feet, it should be possible to pull a string between the two to check positioning. If the viewing angle of the photo-eye is eight degrees or greater, alignment should not be difficult.
The next common reason why so many photo-eyes fail is vibration. Have you ever seen a car or truck wash facility devoid of vibration? With arches turning on and off, and other assorted wash components in constant motion, vibration is certain to occur.
If a photo-eye system is difficult to align when installed, given the amount of on-site vibration, it is highly probable that proper alignment will be difficult to maintain. With a wide opening- angle, or "beam-spread", installation is not only simple, but vibration won't knock the eyes out of alignment.
Mounting plays an important role in photo-eye alignment. In the wash environment, eyes should always be mounted in a through-beam manner (figure 2). Properly mounted eyes promote reliability for the wash over the long haul.
A special word of warning: Do not use reflectors!! (see Pix) In car and truck wash applications, the use of reflectors is a bad idea. Condensation that forms on reflector faces may cause significant problems and they are prone to damage and mischief.
Last, but certainly not least, water leakage can cause photo-eyes to perform intermittently at best, or fail altogether at worst. As water leaks into the housing of the photo-eye, the internal components become damaged and condensation begins to form on the inside of the lens, fogging up glass and plastic lenses alike.
Check the rating on this eye to determine whether it was designed to withstand wash-down or submersion. A rating of IP67 means that a sensor will perform reliably in water. If the photo-eyes in your car or truck wash are not performing up to standards, replace them. Eliminating the problem sensor before it interferes with the performance of the equipment will save you money on those high volume days.
The Right Sensor
Selecting the right sensor for your application can be tricky, and turning the pages of photo sensor catalogs may only add to the confusion.
The components for most infrared systems used in the car wash industry include a transmitter, receiver, amplifier and socket. Don't be tempted to purchase a photo-electric sensor system based on price alone. The cost of installing quality sensor eyes that are made specifically for the car or truck wash is more than justifiable.
As an operator, you're looking for equipment that will perform reliably, day in and day out, with the least amount of maintenance. Remember, your best profit days are when you are managing and the wash is working. Quality eyes will help put you back in the driver's seat of your wash so you can do the important things like servicing and delivering a quality wash.
Light immunity rating, sensing range, strain relief and body style are other features to consider when selecting your sensors; and often the application will help narrow down your choices. For example, if you plan to mount photo-eyes at the entrance to the car or truck wash, a compact body style will simplify installation and service. These sensors should be fully encapsulated, resisting water leakage. The entrance area also subjects the photo-eyes to prolonged exposure to bright sunlight. To avoid intermittent interference, opt for a sensor with a rating of 50,000 LUX or above.
Although operators only need to cover a distance of approximately 10-50 feet, the sensing range of the photo-eye is extremely crucial in carwash applications. Photo-eyes with ranges of 120 feet or more are strongly recommended to ensure that you will have enough power to penetrate the harsh environment caused by dirt, water, soap, fog, etc.
Common applications
Now, let's take a look at some of the most common types of car or truck wash applications.
Self Serve Washes
In self-serve washes, the most common usage is on service-bay automatic doors. Photo-eyes are installed on entrance and exit doors to prevent damage to a car or to the door if the operator closes the door prematurely.
The sensors should be mounted on each side of the door in a through-beam configuration with the transmitter placed on one side and the receiver on the opposite side. (See pix) The amplifier is placed in a watertight enclosure or in the main control panel. As the car comes into or out of the wash, it breaks the infrared beam and signals the door to reverse. Other applications in self-serve washes include automatic entry systems, exit signs, and "unlimited time" self-serve bays.
"Unlimited time" self-serve bays offer extra value to your customers by allowing them plenty of time to clean their vehicles. This may be achieved by installing two photo-electric systems in the bay. One system is used to detect that a vehicle is present in the bay. The second system is used to reset the timer when that customer leaves to prevent the next customer from enjoying a free wash.
Rollover washes
Rollover washes require the car or truck to be driven into the wash and then the machine moves around the vehicle. Photo-eyes are used to position the wash equipment, measure the length of the vehicle and turn the equipment on and off as needed. The entrance and exit doors generally use photo-eyes to signal the PLC or industrial computer that the vehicle has entered or exited the wash.

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CVD-grown monolayered MoS2 as an effective photosensor operating at low-voltage

We report the fabrication of a photosensor based on as-grown single crystal monolayers of MoS2 synthesized by chemical vapor deposition (CVD).

The measurements were performed using Au/Ti leads in a two terminal configuration on CVD-grown MoS2 on a SiO2/Si substrate. The device was operated in air at room temperature at low bias voltages ranging from −2 V to 2 V and its sensing capabilities were tested for two different excitation wavelengths (514.5 nm and 488 nm). The responsivity reached 1.1 mA W−1 when excited with a 514.5 nm laser at a bias of 1.5 V.

This responsivity is one order of magnitude larger than that reported from photo devices fabricated using CVD-grown multilayered WS2. A rectifying-effect was observed for the optically excited current, which was four times larger in the direct polarization bias when compared to the reverse bias photocurrent. Such rectifying behavior can be attributed to the asymmetric electrode placement on the triangular MoS2 monocrystal.

It is envisioned that these components could eventually be used as efficient and low cost photosensors based on CVD-grown transition metal dichalcogenide monolayers.

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iPhone 7 photo sensor and less noticeable antennas?

Contrary to his habits, Apple may not be would review in depth the design of the iPhone for the next generation. In any case it indicated MacRumors citing a source who ” gave accurate information in the past .” According to her, the iPhone 7 overall resume the appearance of current models with two main differences.

The iPhone 7 would ultimately not much different from the iPhone 6 / 6S from an aesthetic point of view. The new smartphones resume the line of current models with some minor modifications. iPhone 7 photo sensor.

The first: Apple has managed to completely return the photo sensor in the chassis. The object would be perfectly flat, as the good old days of 5S and iPhone earlier. The second: Plastic covers for antennas would be less conspicuous, some would be removed to retain bands than at the border. The first involves the rear camera, which protrudes slightly on the iPhone 6 and 6s. On the iPhone 7, the camera is said to sit flush with the rear casing, enabled by a thinner camera module. Recent rumors have indicated Apple is considering equipping the iPhone 7 Plus with a dual-lens rear camera, but the smaller iPhone 7 is expected to include a more traditional camera.

iPhone 7 photo sensor? The supposed result is shown below to get an idea and frankly. We do not believe too. With iPhone sales stalled , it is hard Apple settle for that. The firm must offer something new to clients to get them to purchase. It also goes against the habits of the firm. The strategy is so well oiled, and worked so well so far it seems very difficult to change. Take your tweezers; no, your pliers. iPhone 7 photo sensor



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Exchange the door IFM photo-sensor operating principle of the good fortune

The photo sensor adopts the light cell as the sensor of the detector. It, at first converted to the change of optical signal by the metric change, then further convert the optical signal to the electric signal through the light cell. The photo-sensor is generally made up of light source, optical thorough fare and part of light cell three.

The photoelectric detecting means has advantages such as precision high, reacting fast, non-contact,etc., and there is many measurable parameter, the sensor is simple in construction, the form is flexible, so, it is very extensive that the optoelectronic type sensor is employed in measuring and controlling.

The photo-sensor realizes the key component of photo-electricity translation in various photoelectric detection systems, it is an optical signal ‘ Infrared, can be seen and ultraviolet ray radiation) Change into the device of the electric signal.

The optoelectronic type sensor regards photoelectric device as the sensor of the transition element. It can be used for measuring the non electrical quantity causing the light quantity to change directly, such as light intensity, illuminance, radiating temperature measurement, gas constituent analysis,etc.; Can also use and measure and can convert to the other non electrical quantities that the light quantity changes, such as part diameter, surface roughness, meets an emergency, the displacement, vibration, speed, acceleration, and the shape of object, recognition of working condition,etc.. The optoelectronic type sensor has characteristics such as non-contact, reliable performance fast in response,etc., employed in industry automated assembly and machine philtrum extensively. In recent years, the new photoelectric device is emerging constantly, especially the birth of CCD image sensor, the further application that it is the photo-sensor opened chapter of innovation.

Germany IFM exchanges the door photo-sensor principle of the good fortune
It is varied for action principle [1 ] of the light cell to observe and control the system with optics made by the luminous flux, press the light cell ‘ Optics observes and controls the system) Output quantity properties can be divided class IIly, namely analog photo-sensors and pulses (switch) Type photo-sensor. The analog photo-sensor changes measurand the photo-sensor to become light current of continuous change, it and measurand one is single value relations. The analog photo-sensor presses measurand ‘ Measure the goal object) The method can be divided into transmission ‘ Absorb) The type, it is reflecting type to overflow, lightproof type (light beam hinders the shelf) Three big classes. The so-called transmission type means the testee is put in the light path, the mere energy that the permanent light source gives out crosses the tested subject, after being absorbed partly, the transmitted light throws on the light cell;

Overflow reflecting type to refer to light that permanent light source send out throw at the tested subject while being so-called, and then throw on the light cell after the body surface examined is reflected; The luminous flux that the so-called lightproof type refers to sending out in the light source is only hidden a part among them by the tested subject, make the luminous flux thrown on Jing’s light cell change, intensity and testee changed have something to do with the position of light path.

The light sensitive diode is the most common photosensor. Like general diode, but there is one that inlays the vitreous window on its case in the appearance of the light sensitive diode, so that the light kicks into, accumulated by the grain side in order to increase, the area of the PN junction is made relatively largely, the light sensitive diode works under the back-biased working condition, and connect with the load resistance in series, when there is no illuminationing, it, like general-purpose diode, the reverse current is very small (< micro; A),Called the dark current of the light sensitive diode; When there is illuminationing, current carrier is stimulated, produce the electron-hole, is called the photoelectricity

Germany IFM exchanges door photo-sensor current carrier of good fortune. Under the function of the external electric field, photoelectric current carrier is joined in the electric conduction, form the reverse current much more largely than the dark current, this reverse current is called the light current. The magnitude of the light current is proportional to illumination intensity, then can get the electric signal varying with illumination intensity on the load resistance.

The phototransistor is except that having light sensitive diodes can convert the optical signal to the function of the electric signal, and to the amplifying function of the electric signal. The appearance of the photosensitive triode is pretty much the same as the general triode, the general phototransistor only draws two extremely –Emitter and collecting electrode, the base electrode does not draw, the same windowing of the case, so that the light kicks into. In order to increase the illumination, the area of base region is made very largely, the emitter region is minor, the incident light is mainly absorbed by the base region. The reversal of biasing of the collector junction while working, the emitter junction is forward bias. The electric current that the tube flows through is the dark current Iceo while there is no illumination =( 1


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Plasmonics ramp up nanocrystal photosensor performance

Reporting their results in the journal Nanotechnology, researchers have developed plasmonically coupled light-sensitive skins of nanocrystal monolayers that exhibit sensitivity enhancement and spectral range extension thanks to metallic nanostructures embedded in the photosensitive nanocrystal platform.

Light-sensitive device
As the team from Bilkent University and Nanyang Technological University explains, plasmonic silver nanoparticles within the device increase the optical absorption of a CdTe nanocrystal monolayer. Controlled separation of these metallic nanoparticles in the vicinity of the semiconductor nanocrystals enables optimization of the photovoltage buildup in the device.

The enhancement factor was found to depend on the excitation wavelength. The scientists observed broadband sensitivity improvement (across 400–650 nm), with a 2.6-fold enhancement factor around the localized plasmon resonance peak.

Technology impact
The team’s findings have significant implications for the future design of photosensor platforms. These results could pave the way for the engineering of photosensitive NC-based devices such as smart transparent windows, light-sensitive walls and large-surface optical detection systems.

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Wireless Indoor Optical Positioning With a Differential Photosensor

An indoor optical positioning technique using a differentialphotosensor device is presented. The method is based on angle of arrival information estimated by the differential photosensor in an indoor environment with fixed optical beacons.

A photocurrent is generated by each of the three photodiodes in the photosensor by incident light from the optical beacons. The amplitudes of these photocurrents are a function of the incident angle of the light. Previously derived equations that express photocurrent amplitudes as a function of the azimuthal arrival angle, φ, and the polar arrival angle, θ, are modeled with second- and third-order polynomials, respectively, to determine the φ and θ angles from measured photocurrents.

Testing with optical beacons in various positions with respect to a fixed photosensor resulted in a root mean squared error for all estimated angles φ and θ of 2.8°. A positioning accuracy of better than 4 cm is achieved.

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A self-powered photosensor switch detects only rising edge of infrared-light pulse for wireless zero-standby-power wake-up receiver

A self-powered photosensor switch that detects only the rising edge of an infrared (IR) pulse has been developed to reduce the standby current of battery-operated wireless devices with an IR remote controller and to enable removal of the external on/off switch. It consists of a V_DD-rising-edge detector, an external-noise current canceller, and an IR LED energy harvester.

The detector is powered by the energy harvester and detects a steep rising edge in the supply voltage. The power dissipation of the detector is kept at the picowatt level so that the detector operates only when the supply voltage passes through the sub-Vth region. The external-noise current canceller subtracts the offset current due to environmental noise. It uses a diode-connected low-Vth MOSFET to reduce the supply voltage to less than the operating voltage of the detector, and it keeps the supply voltage constant at a value determined by the constant current source of a low-Vth MOSFET in which the gate is replaced with a hold capacitor.

The photosensor switch makes possible the self-powered detection of IR light signals from a remote controller, even in the presence of environmental noise. To verify its effectiveness, a wake-up receiver containing the photosensor switch was fabricated and tested on a battery-operated wireless device. A commercial IR remote controller was able to wake the device up at a distance of 6 meters, and the standby current of the power-on controller was found to be 0.5 nA. The power dissipation of the photosensor switch was 40 pW.

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Photosensor circuits including a regulated power supply

Photosensor circuits include a relay coil configured to control application of an alternating current (AC) power source to a load. The circuit includes a pulse width modulator circuit configured to generate a pulse width modulated signal having a pulse width that varies responsive to an average voltage across the relay coil. A drive transistor coupled to the relay coil controls the average voltage across the relay coil responsive to the pulse width modulated signal. A photo control circuit is configured to control application of the pulse width modulated signal to the drive transistor responsive to a detected light level. A power circuit coupled to the power source is configured to provide a regulated power signal to a comparator of the pulse width modulator circuit.

BACKGROUND OF THE INVENTION
The present invention relates to photosensor circuits and, more particularly, photosensor circuits for light level switching control.

Photo controllers are devices that automatically turn electrical devices on and off in response to the ambient light level. They are used, for example, on street lights to automatically turn them off during the day and on at night. They are also used on billboard lighting systems to turn the billboard lights on early at night, off late at night during periods of low vehicular traffic, on again during early morning rush hour periods when high traffic levels resume, and then off during the daylight hours. Photo controllers may also be used in reverse, for example, to turn a golf course water fountain on during the day and off at night.

A variety of devices, including photo controllers, may make use of power converters to convert relatively high voltage alternating current to relatively low voltage direct current as is used in many conventional electronic devices. Some conventional power converters make use of large, high-voltage resistors to drop the voltage. However, these resistors are typically inefficient and generate high heat. The heat generated from the resistors may require that the resistors be housed in a large package and include heat dissipating elements, such as heat sinks. Also, the high heat generated by the resistors can lead to problems with reliability and longevity in the resistors and in other electronic components situated near the resistors.

Another conventional approach to power conversion is the use of a switch mode power converter. The switch mode power converters typically require six transistors or a micro-controller to implement. The requirement for multiple transistors or a micro-controller may cause the implementation of switch mode power converters to be cost prohibitive in some applications, such as in photo controllers.
A small, low cost, efficient switch mode power converter and a photosensor circuit including the same are described in U.S. Pat. No. 6,903,942 (“the '942 patent”), which is hereby incorporated herein by reference as if set forth in its entirety.

It is also known to provide a photosensor circuit including digital circuitry as incorporated in the 3100 Series photocontrol, available from TE Connectivity. The photosensor circuit for the 3100 Series photocontrol is shown in FIG. 1. As seen in FIG. 1, a microcontroller U1 outputs a signal GP4 that drives a drive transistor Q2 to turn on and off the drive transistor Q2 as part of a pulse width modulated control circuit including capacitors C5 and C6 and diode D2 (operating at a frequency of approximately 50 Hertz (Hz) to control the voltage across the relay coil of the relay K1. Relay K1 is shown as a normally open relay and, when light is detected by photransistor Q1, the coil current of relay K1 is turned off to turn off a load LOAD, such as a street light. A direct drive signal is provided by including capacitor C3 to adjust voltage levels of the signal to the base of the drive transistor Q2 from the signal GP4. In addition, a half wave rectifier (diode D1) is included to provide power for the photocontrol circuit.

A regulated power supply is also shown to provide the power supply signals VSS and VDD to allow operation of the microcontroller U1. In the illustrated embodiment, VSS is coupled to the AC line NEUTRAL to provide the DC ground reference. The VDD signal is provided by the resistor R7 coupled to the half wave rectifier D1. In addition, The VDD signal is coupled to the emitter of the drive transistor Q2. As such, current will also be provided through the drive transistor Q2 but only when the transistor is on.

A small, low cost, efficient switch mode power converter including a regulated power source for a microcontroller is also described in co-pending U.S. patent application Ser. No. 13/190,727 (“the '727 application”), which is hereby incorporated herein by reference as if set forth in its entirety.
Regulated power sources may also be used in photocontroller circuits not including a microcontroller, such as described in U.S. Pat. No. 8,026,470 (“the '470 patent”), which is hereby incorporated herein by reference as if set forth in its entirety.

SUMMARY OF THE INVENTION
Embodiments of the present invention provide photosensor circuits including a relay coil configured to control application of an alternating current (AC) power source having a negative half and a positive half of a line cycle to a load. A pulse width modulator circuit of the photosensor circuit is configured to generate a pulse width modulated signal having a pulse width that varies responsive to an average voltage across the relay coil. The pulse width modulator circuit includes a comparator. A drive transistor coupled to the relay coil that controls the average voltage across the relay coil responsive to the pulse width modulated signal. A photo control circuit of the photosensor circuit is configured to control application of the pulse width modulated signal to the drive transistor responsive to a detected light level. A power circuit, coupled to the power source, is configured to provide a regulated power signal to the comparator of the pulse width modulator circuit. The power circuit includes the drive transistor coupled between the relay coil and the regulated power signal and a second transistor coupled between a base of the drive transistor and the regulated power signal. The drive transistor conducts current passing through the relay coil to the regulated power signal when the drive transistor is on and the second transistor conducts current not passing through the relay coil to the regulated power signal when the drive transistor is turned off.


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