TRANSPARENT LIGHT SENSING DEVICE, IN PARTICULAR FOR AN ELECTRONIC DISPLAY DEVICE, AND A METHOD FOR MONITORING AN ELECTRONIC DISPLAY

Abstract

 A transparent light sensing device comprises a sensing element having a plurality of transparent sensor areas that comprise a light-sensitive material, wherein each sensor area is configured to convert light passing through the sensor area into an electrical signal; and an detector circuit for processing the electrical signal received from each of the sensor areas into a format that can be processed by a computer or an embedded system.

Description

[0001] The present invention relates to a transparent light sensing device and, in particular, to a transparent light sensing device for an electronic display device and to a method for monitoring an electronic display.

[0002] Displays of all types are common in automotive applications. Depending on the information shown by the display, the display may comprise a combination of electrical and mechanical parts, such as lamps and gauges, or electronic display technology such as TFT, LCD, OLED or head-up technology.

[0003] As the sophistication of display technology increases, the effort and technology required for monitoring and determining their reliability becomes increasingly complicated. There may also be additional factors that lead to strict reliability requirements, for example, the legal requirements placed on displays for safety-critical information, which may include information on the brake system, airbags, required maintenance or the like. Given a simple system in which a lamp is illuminated behind a physical cutout in the instrumentation panel to display a warning light, past systems monitored the lamp itself for defects to determine whether the display works properly. However, for sophisticated electronic display systems that are able to display different types of information, it is necessary to monitor the system both with regard to simple defects and to the content being displayed.

[0004] One way to monitor the content, i.e. the text and/or image, shown by an electronic display is to provide a conventional camera that captures the content shown to the driver. The image captured by the camera may be processed using image processing technology and compared with a stored image or any kind of data representing the image to determine whether the display is showing the correct content. However, a special camera for this purpose entails additional cost and complexity. In addition, space is at a premium in a vehicle cockpit, which makes the placement of such a camera difficult.

[0005] Thus, there remains a need for improved devices and methods for monitoring electronic displays.

[0006] Accordingly, a first aspect of the invention provides a transparent light sensing device that comprises a sensing element with a plurality of transparent sensor areas. In this context, transparency also includes translucency to the extent that a translucent material enables the formation or transmission of an image with little or no distortion of the image. Each sensor area includes a light-sensitive material and is configured to convert the light passing through the sensor into an electrical signal. The light sensing device further comprises a detector circuit to receive and process the electrical signal from each of the sensor areas into a format that can be processed by a computer or an embedded system.

[0007] Due to the transparency of the sensor areas, the light sensing device in accordance with the present invention can be used to detect the light transmitted through a transparent object, for example, through a window or plate glass with, at most, a minimal obstruction of the view through said window or glass. Accordingly, the light sensing device is more flexible in its placement than a conventional camera having an opaque housing.

[0008] In accordance with an embodiment of the invention, the light sensing device is paired with a display screen to provide an electronic display device with a monitoring function. In this embodiment, the display screen comprises a plurality of display regions, and the light sensing device is arranged adjacent to the display screen such that the sensor areas of the sensing element overlap the display regions. The display regions of the display screen are configured to form an image or display text by emitting light or by reflecting ambient light through at least one of the sensor areas of the sensing element. Each sensor area converts the light transmitted through it into an electrical signal received by the detector circuit of the light sensing device, which processes the electrical signal from each of the sensor areas into a format that can be processed by a computer or an embedded system.

[0009] The electronic display device further comprises a control system that receives the formatted electrical signals from the detector circuit and compares the electrical signal corresponding to each sensor area with pre-determined data. If the control system determines that the electronic signal from a sensor area does not correspond to the pre-determined data, the control system may react in a pre-defined manner, such as by providing an alert or by initiating a treatment of the issue.

[0010] In this embodiment, the pre-determined data may correspond to a parameter of the light emitted by the display regions of the display screen, such as its brightness or color. If a display region of the display screen is only used to display one pre-determined symbol, the brightness and/or color of the display region can be monitored by the corresponding sensor area to determine whether the symbol is shown.

[0011] By scaling the size of each sensor area and the total number of sensor areas, the light sensing device can be adapted to the resolution necessary for a particular application. For example, each pixel of an electronic display screen may be considered as an independent display region. Accordingly, each pixel of the display screen can be monitored separately if the sensing element of the light sensing device comprises an appropriately sized and arranged sensor area for each display pixel. This variant may be used to monitor a display screen that shows different, changing symbols, images or words. Specifically, a graphics processing unit of the control system may process the electrical signals for each pixel into an image, while a comparison unit compares the processed image with suitable data, such as an image signature that represents the image corresponding to the correct or anticipated image.

[0012] In accordance with this embodiment, the placement of the light sensing device relative to the display screen may vary as long as the light sensing device and display screen are adjacent to one another. In practice, this may mean that the sensing element of the light sensing device is placed in front of or behind the display screen or is even integrated into a display structure. For example, in a vehicle, the sensing element may be arranged directly on the display screen itself or arranged on or integrated into the windshield, windows, or the glass covering the instrumentation panel. The sensing element may also be arranged between the display screen and a light source, in particular a backlight of the display screen. The sensing element may even be formed as a layer of the display screen, which may comprise, for example, OLED, LCD or TFT technology. This flexible placement of the light sensing device results in a compact and unobtrusive device.

[0013] Additionally, the electronic display device may comprise a closed-loop system in which the control system controls the display screen based on the electrical signals received from the sensor areas to improve reliability or the appearance of the image shown at the display screen.

[0014] In one embodiment, the control system may adjust the operational parameters of at least one display region of the display screen in dependence on the electrical signal generated by the sensor area corresponding to said display region. For example, if the control system determines that the light emitted from a sensor area is insufficiently bright or has the wrong color, the control system may respond by adjusting the brightness or wavelength of the emitted light, thus enhancing the visibility of the displayed image.

[0015] Additionally or alternatively to this, the control system may command a first display region to emit light to form an image in dependence on the electrical signal generated by a sensor area corresponding to a second display region. In other words, if the control system determines that one display region is defective, it may command another display region to display the image intended for the defective display region, thus increasing the reliability of the device.

[0016] In one exemplary embodiment, the light sensing device may include a sufficiently transparent, organic solar cell. Accordingly, the sensor areas of the sensing element may comprise light-sensitive materials used in organic solar cells or materials similar to those used in organic solar cells. Such materials include organic salts or molecules, which are configured to react to a specific range of wavelengths of light and convert the transmitted light into electric signals. Instead of using the electrical signals to generate energy, they are transmitted to the detector circuit and processed by the control system into an image. However, it is also conceivable to use other materials that are suitable for forming a transparent light sensing device, such as electronic semiconductor materials.

[0017] Furthermore, a second aspect of the present invention provides a method of monitoring an electronically displayed image comprising the steps of forming an image by emitting or reflecting light from a plurality of display regions of a display screen; transmitting the emitted or reflected light through a plurality of transparent sensor areas of a sensing element of a transparent light sensing device; converting the light transmitted through each sensor area to an electrical signal; receiving and processing the electrical signal received from each sensor area into a format that can be processed by a computer or an embedded system; and comparing each formatted signal received from the sensing element with pre-determined data.

[0018] In accordance with one embodiment, the method comprises the additional step of adjusting the operational parameters of one or more display regions, in particular the brightness or wavelength of the emitted light, in dependence on the comparison of the formatted signal and the pre-determined data.

[0019] In an embodiment in which the display screen is configured to form an image by emitting light, the ambient light surrounding the display screen may be determined, and the brightness of the emitted light adjusted accordingly, so that the emitted light is brighter than the ambient light. This results in improved visibility of the displayed image. Additionally, the influence of the ambient light may be eliminated from the formatted signals received from the sensing element by means of software calculations prior to the comparison of the formatted signals with the pre-determined data. This results in a more accurate comparison between the electrical signals of the sensing element and the pre-determined data.

[0020] The method may comprise the additional step of commanding a first display region to emit light to form an image in dependence on the comparison between a formatted signal corresponding to a second display region with its pre-determined value. In this way, when a defective display region is detected by the control system, its contents may be displayed at a different, operational display region.

[0021] In another embodiment, the display screen comprises a projection surface such as the windshield of a vehicle, and the image is formed by reflecting light from a light source from the projection surface, in particular from a laser light source, in the manner of a head up display. In this embodiment, the light sensing device may be placed so that it monitors the reflected image, or the light sensing device may be placed in the path of the beam emitted from the light source between the light source and the projection surface. This embodiment makes it possible to accurately and unobtrusively monitor the contents projected by a head-up device.

[0022] The display screen of the foregoing embodiments may display content or information comprising text, images or symbols alone or in combination with one another. For the sake of simplicity, the following description refers only to images, but it is understood that this expression also extends to these other types of content shown by the display screen.

[0023] Various features and advantages of the present invention will become more apparent from the following description and accompanying drawing wherein:

Fig. 1a

shows a transparent light sensing device in accordance with the present invention;

Fig. 1b

shows an enlarged cross-section of the light sensing device of Fig. 1 a;

Fig. 2

shows an electronic display device including a transparent light sensing device in accordance with the present invention;

Fig. 3

shows a cross-sectional view of the electronic display device of Fig. 2; and

Fig. 4

is a schematic diagram of the control system of the electronic display devices of Fig. 2 and 3.

[0024] Referring to the figures, wherein like numerals indicate corresponding parts throughout the several views and aspects of the invention, a transparent light sensing device 10 comprises a sensing element 12 having a plurality of transparent sensor areas 14, 14' that comprise a light-sensitive material. In particular, the sensor areas 14, 14' comprise both large sensor areas 14 as well as small sensor areas 14'.

[0025] The transparent light sensing device 10 may therefore be arranged on a transparent material 16 with at most minimal obstruction of the visible radiation passing through the transparent material 16 (Fig. 1 b). Though

[0026] Fig. 1 a shows a sensing element 12 that only covers a portion of the surface area of the transparent material 16, it is also possible to cover the entire visible surface area of the transparent material 16 with the sensing element 12. Furthermore, though Fig. 1b shows the light sensing device 10 and specifically the sensing element 12 as a layer formed on top of the transparent material 16, it is also conceivable to form the light sensing device 10 as part of the transparent material 16 itself.

[0027] In this context, transparent means that light rays L are transmitted through the sensor areas 14 with acceptably low interference, as opposed to being absorbed or reflected, as shown in Fig. 1 b. Specifically, each of the sensor area 14, 14' is configured to convert the light rays L that pass through the sensor area 14, 14' into an electrical signal, which is received by a detector circuit 18 (Fig. 1 a) that process the electrical signal received from each sensor area 14, 14' into a format that can be processed by a computer or by an embedded system.

[0028] Turning to Fig. 2 to 4, an electronic display device 22, including a transparent light sensing device 10 in accordance with the invention, is shown. Fig. 2 indicates one active display region 24, but it is understood that the display screen comprises further display regions that are inactive in the drawing. Additionally, though the display region 24 comprises multiple image pixels that form a warning symbol, it is also possible to consider each pixel as its own display region.

[0029] For creating an image, the shown display screen comprises a display driver 26, backlight LED 28, and a light guide 30. The sensing element 12 of the light sensing device 10 is arranged adjacent to the display screen, i.e. on top of the display screen 32 (Fig. 3). However, it is also possible for the sensing element 12 of the light sensing device 10 to be integrated into the display screen itself. As a result, the small sensor areas 14' of the sensing element 12 overlap with the display region 24 of the display screen. In Fig. 2, the sensing element 12 is interrupted by a broken line, but it is understood that the display region 24 is entirely covered by the sensor areas 14'. In the illustrated view, the larger sensor areas 14 of the sensing element 12 cover, for example, the aforementioned, inactive additional display regions.

[0030] For example, the electronic display device 22 comprises a housing 34 that contains the display screen components. Though the light sensing device 10 in Fig. 3 is arranged above the housing 34, it is also possible for the display screen and the light sensing device 10 to be arranged in a common housing.

[0031] As shown in Fig. 3, the backlight LED 28, which are mounted, for example, on a circuit board 36, emit light rays L that are reflected off a reflector 38 and through the light guide 30 and the display glass 32, such as a TFT display glass. After the light rays L exit the display glass 32, they pass through the sensor areas 14 of the sensing element 12. The light-sensitive material of each sensor area 14 is configured to react to the light, for example, the brightness or the wavelength of the transmitted light ray L, and generate an electrical signal transmitted to the detector circuit 18. The detector circuit 18 then processes the received signals into a format suitable for processing by a computer or an embedded system and transmits the signals to a control system 40, for example a microcontroller, as shown in Fig. 4.

[0032] Fig. 4 illustrates that the formatted signals from the detector circuit 18 are received by a graphics processing unit 42 to process the signals into data representing an image. The data created by the graphics processing unit 42 is then transmitted to a comparison unit 44, that compares the data with pre-determined data 46, such as an image signature representing the expected image, to determine both whether the display screen is operational, i.e. displays an image, and whether the displayed image is correct. If the comparison unit 44 determines that the data representing the image do not correspond to the pre-determined data 46, the control system 40 may initiate an appropriate reaction, such as an alert, to which another external device may react. The control system 40 may also initiate a suitable internal reaction in a digital content creation module 50, for example so that the display screen displays a warning or error message that a portion of the display screen is not working correctly.

[0033] If the displayed image itself is correct, but the brightness and/or color of the displayed image is not correct, a further graphics processing unit 48 that generates the display content by communicating with the display driver 26 and the digital content creation module 50 may adjust the corresponding parameters of the image to be displayed and/or of the display screen to adjust the brightness or the wavelength of the light emitted by the backlight 28.

[0034] If the control system 40 detects that a display region is defective, i.e. does not display an image at all or displays an incorrect image, the control system 40 may command the digital content creation module 50 to display the desired symbol at another display region with no monitored defects.

[0035] In order to improve the monitoring of the display regions, the control system 40 may also determine the brightness of the ambient light surrounding the electronic display device using a suitable sensor (not shown), and the graphics processing unit 42 may eliminate the influence of the ambient light from the processed image by means of software calculations prior to the comparison of the image to the pre-determined data 46. Alternatively or additionally, the graphics processing unit 48 and/or the display driver 26 may adjust the parameters of the display screen based on the detected brightness of the ambient light.

[0036] In contrast to the embodiment shown at Fig. 2 to 4, the light sensing device 10 may be arranged between a display glass and a backlight in an electronic display device, for example, a TFT device. In this arrangement, the light sensing device 10 is used to monitor a reflected image of the image shown at the display screen. Alternatively, both the light sensing device 10 and the display screen may be formed using the same technology, for example organic technology, such that they can be manufactured as layers of a single device.

[0037] Furthermore, if the electronic display device 22 uses a technology that incorporates self-illuminated pixels, for example OLED or tube-type displays, then the source of light is not the backlight, but rather the pixel itself. In this embodiment, the light sensing device 10 may be placed in any configuration adjacent to the display screen as long as the light emitted by the pixels passes through the sensor areas. As described above, this may be in front of the display screen or even integrated into the display screen.

[0038] Additionally, the light sensing device 10 may be arranged on, in or behind a passive display screen that does not use or contain its own light source so that that the display screen reflects ambient light, but does not actively emit light in the way shown in Fig. 1 a and 1 b. Similarly, the light sensing device 10 may also be arranged at, on or integrated in a vehicle windshield so that it may monitor a reflected image projected by the light source of a head-up display system. If a light beam is used as a light source, for example a projector or a laser light source, the light sensing device 10 may be placed anywhere within the path of the light beam containing the image information to be monitored. However, the light sensing device 10 may also be placed at a projection surface, such as the windshield of a vehicle.

List of reference numerals

[0039] 

10

transparent light sensing device

12

sensing element

14, 14'

sensor area

16

transparent material

18

detector circuit

20

frame

22

electronic display device

24

display region

26

display driver

28

backlight LED

30

light guide

32

display glass

34

housing

36

circuit board

38

reflector

40

control system

42

graphics processing unit

44

comparison unit

46

pre-determined data

48

graphics processing unit

50

digital content creation module

L

light ray

Claims

1. A transparent light sensing device (10) comprising:

a sensing element (12) having a plurality of transparent sensor areas (14, 14') that comprise a light-sensitive material, wherein each sensor area (14, 14') is configured to convert light passing through the sensor area (14, 14') into an electrical signal; and

a detector circuit (18) for processing the electrical signal received from each of the sensor areas (14, 14') into a format that can be processed by a computer or an embedded system.

2. An electronic display device (22) comprising a transparent light sensing device (10) in accordance with claim 1 and a display screen having a plurality of display regions (24);
wherein the light sensing device (10) is arranged adjacent to the display screen such that the sensor areas (14, 14') of the sensing element (12) overlap the display regions (24) of the display screen;
wherein the display regions (24) of the display screen are configured to emit light or reflect ambient light that forms an image and is transmitted through at least one of the sensor areas (14, 14') of the sensing element (12);
wherein the sensor area (14, 14') converts the transmitted light to an electrical signal received by the detector circuit (18) of the light sensing device (10); and
wherein the electronic display device (22) further comprises a control system (40) that receives the formatted electrical signals from the detector circuit (18) and compares the electrical signal corresponding to each sensor area (14, 14') with pre-determined data (46).

3. An electronic display device (22) in accordance with claim 2 wherein the sensing element (12) of the light sensing device (10) is arranged between the display screen and a light source, in particular a backlight (28).

4. An electronic display device (22) in accordance with claim 2 or claim 3 wherein the control system (40) adjusts the operational parameters of a display region (24), in particular the brightness or wavelength of the emitted light, in dependence on the electrical signal generated by the sensor area (14, 14') corresponding to said display region (24).

5. An electronic display device (22) in accordance with any one of the claims 2 to 4 wherein the control system (40) commands a first display region to emit light to form an image in dependence on the electrical signal generated by a sensor area (14, 14') corresponding to a second display region.

6. An electronic display device (22) in accordance with any one of the claims 2 to 5 wherein each display region (24) of the display screen corresponds to an image pixel.

7. An electronic display device (22) in accordance with claim 6 wherein each sensor area (14, 14') overlaps and corresponds to exactly one display region (24).

8. An electronic display device (22) in accordance with any one of the claims 2 to 7 wherein the display screen comprises an OLED, LCD or TFT device.

9. An electronic display device (22) in accordance with any one of the claims 2 to 7 wherein the light sensing device (10) is integrated into a display structure or housing of the display screen.

10. A method of monitoring an electronically displayed image comprising the steps of:

forming an image by emitting or reflecting light from a plurality of display regions (24) of a display screen;

transmitting the emitted or reflected light through a plurality of transparent sensor areas (14, 14') of a sensing element (12) of a transparent light sensing device (10);

converting the light transmitted through each sensor area (14, 14') to an electrical signal;

receiving and processing the electrical signal received from each sensor area (14, 14') into a format that can be processed by a computer or an embedded system;

comparing each formatted signal received from the sensing element (12) with pre-determined data (46).

11. A method in accordance with claim 10, further comprising the step of adjusting the operational parameters of one or more display regions (24), in particular the brightness or wavelength of the emitted light, in dependence on the comparison of the formatted signal and the pre-determined data (46).

12. A method in accordance with claim 10 or claim 11, further comprising the step of determining the brightness of the ambient light, wherein the image is formed by emitting light from the plurality of display regions (24) at a brightness that is greater than the brightness of the ambient light.

13. A method in accordance with claim 12, further comprising the step of eliminating the influence of the ambient light from the formatted signals received from the sensing element (12) by means of software calculations prior to the comparison of the formatted signals with the pre-determined data (46).

14. A method in accordance with any one of the claims 10 to 13, further comprising the step of commanding a first display region to emit light to form an image in dependence on the comparison between a formatted signal corresponding to a second display region with its pre-determined data (46).

15. A method in accordance with any one of the claims 10 to 14 wherein the display screen comprises a projection surface, such as the windshield of a vehicle, and the image is formed by reflecting light from a light source, in particular a laser light source, onto the projection surface in the manner of a head up display.

Drawing