CN106458030B

CN106458030B - Method for operating a display device, in particular for a motor vehicle, and display device therefor

Info

Publication number: CN106458030B
Application number: CN201580029978.3A
Authority: CN
Inventors: S.文克
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-06-06
Filing date: 2015-04-29
Publication date: 2019-12-24
Anticipated expiration: 2035-04-29
Also published as: WO2015185298A1; CN106458030A; DE102014210834B3

Abstract

The invention relates to a method for controlling a display device (1), in particular for a motor vehicle, comprising a display (3) having a plurality of picture elements (4), wherein the picture elements (4) are operated as a function of a control variable in addition to a minimum value and a maximum value for the light intensity for the picture elements, characterized in that the picture elements (4) are periodically operated with the minimum value and the maximum value for the light intensity of the picture elements in at least one part of the display area, the distance between the minimum value and the maximum value of the light intensity is repeatedly measured, the display device (1) is at least partially restarted if the measured distance value falls below a predefined minimum value at a predefined first frequency, and in the case of a predefined second frequency which is carried out below the minimum value, -switching off the display device (1).

Description

Method for operating a display device, in particular for a motor vehicle, and display device therefor

Background

The invention relates to a method and a device for controlling a display device according to the preambles of the independent claims.

DE 10138005B 4 discloses a display device for a vehicle, which comprises a color-developable, in particular flat display and a control element. The control element is designed to compensate for an undesired color shift in order to determine a control variable as a function of at least one non-control variable of the display device, and has a light sensor for measuring the light intensity, which is optically connected to the display surface of the display via a light decoupling element.

Furthermore, DE 10159051 Al discloses a method for controlling a display device for a vehicle, which display device comprises a display unit with a display surface having a plurality of picture elements and a control element for the display unit. On the display surface, in addition to the minimum and maximum values for the picture element-light intensity, a plurality of intermediate values of the light intensity can be shown. In this case, the value for the luminous intensity of the picture element, which lies in the range of the saturation value of the luminous intensity, is represented exclusively on at least one section of the display surface. In this case, a reference value is determined on the basis of the measurement of this part of the display surface, which reference value is to be obtained in the case of a known value of the actuation variable. Furthermore, for the known values of the manipulated variable, the actual value of the light intensity is determined. The value of the manipulated variable is corrected in the positive or negative direction with respect to the starting value if there is a significant difference between the reference value and the actual value.

Disclosure of Invention

The invention is based on a method for operating a display device, in particular for a motor vehicle, having the features of the independent claim. The display device comprises a display with a plurality of picture elements, wherein the picture elements are operated as a function of operating variables in addition to minimum and maximum values for the picture elements, i.e. light intensity, in order to ensure the highest possible contrast representation of, for example, vehicle-specific information, such as speed, rotational speed, energy consumption, oil pressure, etc., and/or image content, such as navigation instructions, on the display.

In this context, light intensity is to be understood as meaning corresponding, specific physical or photometric variables, such as, for example, radiation power, radiation intensity or luminous flux, light intensity or brightness. For example, the minimum value and the maximum value of the luminance of the display portion can be 0.1 cd/m²Or 500 cd/m²。

The control variable can be understood as the current or voltage itself or can be, for example, pulse-width modulated.

According to the invention, in at least one part of the display surface, the picture element is periodically operated with its minimum and maximum values of the light intensity and the distance between the minimum and maximum values of the light intensity is continuously measured. The display device functions correctly if the distance between the minimum and maximum values of the light intensity exceeds a predefined minimum value. If the measured distance value falls below a predetermined minimum value at a predetermined frequency, the display device is at least partially restarted in order to avoid erroneous displays and in order to establish a reliable operation again.

Frequency is to be understood here as the absolute number below the minimum value and the number below the minimum value in a defined time interval.

After at least partial restart, the distance between the minimum and maximum light intensity values is again measured continuously. The display device functions correctly if the distance between the minimum and maximum values of the light intensity exceeds a predetermined minimum value. However, if the distance between the minimum and maximum light intensity values is again below the predetermined minimum value at predetermined times, the display device is switched off and the driver of the vehicle is signaled, for example by a warning tone, an LED warning light or a voice output: the display device is set out of operation due to a functional fault, since the display unit functions incorrectly and thus does not ensure: informing the driver about a critical vehicle parameter. Thus, completely turning off the display is more secure than providing the driver with an unreliable source of information.

Advantageous modifications and improvements of the method described in the independent claims are possible due to the measures listed in the dependent claims.

So that, for example, it is possible to specify: at least partial restarting of the display device takes place after two undershoots, but the switching off of the display device is only triggered after a further number of undershoots. This has the advantage that early attempts were made to: the problem is eliminated by restarting, but the display device is relatively forgiving to be configured for: the shutdown is only performed when at least a partial restart does not result in a functioning runtime. Thereby, redundant shutdown is avoided.

In a further embodiment of the invention, it is provided that the restarting of the part of the display device takes place after two drops below the minimum value and the switching off of the display device takes place after another drop below the minimum value. This variant is advantageous for low-tolerance operation of the display device.

It is furthermore advantageous for the frequency with which the picture element is periodically operated between its minimum and maximum light intensity to be matched to the frame rate of the display. Preferably, the frequency is smaller than, particularly preferably equal to, the frame rate of the display, since this simplifies the actuation of the individual image elements and of the entire display.

In a further advantageous embodiment, the frame rate of the display and thus the frequency with which the picture element is periodically operated between its minimum and maximum light intensity are adapted to the temperature of the display. Thus, the fact is considered: the reaction time of the display increases with decreasing temperature, and thus the image content is no longer built up and subtracted or converted as quickly as when the temperature is higher. This ensures that the display also functions reliably in a wide temperature range.

It is also advantageous to manipulate and operate the image elements monochrome. When the picture elements are operated between their minimum and maximum light intensities in one of the three primary colors, red, green and blue, respectively, one after the other for a specific, freely selectable period of time, the correct color representation of the individual colors of the display can be checked. This results in the display reliably functioning even in the case of a color representation of the display information.

Since the contrast of the display is also dependent on the intensity of the backlighting, it is advantageous to measure the intensity of the backlighting alone or to know an empirical model of the intensity profile of the backlighting over time. Since these effects can then be calculated therefrom, which effect influences the spacing between the minimum and maximum of the picture element-light intensity and thus the contrast of the display. This ensures reliable operation of the display even when the display is dimmed or when the display is illuminated by an external light source, for example a low sun.

It is also advantageous to know, for example, the dependence of the contrast on the temperature present at the display and on the age of the display. Since the contrast can then be adjusted in addition via the brightness of the backlighting portion of the display portion, for example when the contrast decreases with a higher temperature of the display portion or a higher age of the display portion.

In a display device, in particular for a motor vehicle, comprising a display unit with a plurality of picture elements which, in addition to minimum and maximum values for the picture elements, can be operated using a plurality of intermediate values of the light intensity as a function of a manipulated variable, the following means are provided according to the invention. A sensor for measuring the light intensity, an evaluation unit for checking whether a predefined minimum distance between a minimum and a maximum of the light intensity is to be followed in at least one section of the display area, a storage unit for storing a frequency which is lower than the predefined minimum distance between the minimum and the maximum of the light intensity, and a control unit for periodically operating the picture elements of the display with their minimum and maximum of the light intensity, for at least partially restarting the display, and for switching off the display.

In a preferred embodiment of the invention, the display can be a flat display, in particular a liquid crystal display. This has the advantage that, due to the flat design, only a small installation space is required. Further, a liquid crystal display portion has been established in the market.

It is furthermore provided that the display can be designed as a color-developing display, wherein the picture elements are composed of three primary color sub-picture elements, namely red, green and blue. In this case, it is advantageous that monochromatic as well as colored image content can be displayed.

For the light intensity measurement, the sensor, which can be embodied, for example, as a photodiode or a phototransistor, is advantageously mounted in a region of the display which is covered by a screen so that it is not visible to an observer of the display.

In a further advantageous embodiment of the invention, a temperature sensor is attached to the display in order to measure the temperature of the display. The frame rate of the display and thus of the image elements monitored by the sensor can thus be adapted to the temperature, so that a reliable display operation is possible and can also be monitored over a wide temperature range occurring in the vehicle.

Drawings

Embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description.

The figure is as follows:

FIG. 1: a schematic presentation of a display device with an operating control and an evaluation unit;

FIG. 2: a flow chart for adjusting the correct operation of the display device.

Detailed Description

A schematic illustration of a display device 1 is shown in fig. 1. The display device 1 is integrated in a combination device 2, which is installed in a motor vehicle. Basically, the visible part of the display device 1 comprises a display section 3, which can be realized, for example, by a liquid crystal display section. Alternatively, the display 3 can also be embodied as an organic (organic) light-emitting diode display or as a plasma display. The display unit 3 may be a monochrome display unit or may be a color display unit. In the first embodiment, the display portion 3 can fill the entire area of the combination meter 2. Alternatively, however, the display can also be limited to a partial region in front of the driver, for example.

The display 3 is formed from a plurality of individually controllable image elements 4 and is illuminated in the embodiment as a liquid crystal display by a backlighting 5. The backlighting 5 can be formed, for example, by means of light-emitting diodes.

A plurality of vehicle-specific information and/or image contents can be presented to the driver of the vehicle, for example, on the display unit 3 of the display device 1. So that, for example, a speed display 6 and a rotational speed display 7 as indicator devices can be displayed. It is also conceivable to display the values of the speed display 6 and/or of the rotational speed measuring device 7 in the form of numbers. It is also possible for the last traveled route section or the total traveled route sections to be displayed in the form of a numerical sequence via the display area 8. It is also expedient to present the additional information in a further display area 9. These display areas can also include an external temperature display, ice warning, spacing warning, oil level display, tank display, or other control lights for vehicle functions. Each individual warning can be displayed in the combination meter 2 and on the display 3.

The display device 1 further comprises a controller 10, which is designed, for example, as a microcontroller. Furthermore, the display device 1 comprises an evaluation unit 11, which is connected to the controller 10. The controller 10 is also connected to the backlight portion 5 of the display portion 3 via an energy supply unit 12 for the backlight portion 5. The display device 1 is connected via the control unit 10 to a signal processing device 18 of the vehicle, for example a CAN bus or to a separate line. Via this signal processing device 18, all relevant information is transmitted to the control unit 10, which should be presented on the display 3.

An optical sensor 13 is mounted on the display surface of the display 3, preferably in a corner or edge region of the display surface. Which monitors the light intensity of the picture elements 4 on a specific defined area of the display 3. The optical sensor 13 can be, for example, a photoelectric sensor or a phototransistor. The optical sensor 13 is connected to the evaluation unit 11.

A temperature sensor 14 is also attached to the display unit 3. The temperature sensor is preferably also arranged at a corner region or an edge region of the display. The temperature sensor 14 is connected to the evaluation unit 11.

In a particular embodiment of the invention, the optical sensor 13 is mounted on the display in such a way that it is covered by the frame 19 or the bulkhead 19 of the cluster 2 and cannot be felt by the driver.

In a typical embodiment of the invention, the temperature sensor 14 is mounted on the display in such a way that it is covered by the frame 19 or the partition 19 of the cluster 2 and cannot be felt by the driver.

The evaluation unit 11 evaluates the signals of the optical sensor 13 and the signals of the temperature sensor 14. The evaluation unit 11 delivers the evaluated signal to the controller 10. The controller 10 (which, in addition to the computing unit 15, also includes a memory unit 16) is connected via a further interface to an acoustic signal transmitter 17, for example a loudspeaker.

The controller 10, which preferably controls the image content of the backlighting 5 and the display 3 via the energy supply 12, enters such values together into its regulating algorithm, which it obtains from the control unit 11.

The controller 10 also controls the image element 4, whose light intensity is detected by an optical sensor 13. In order to check the correct operation of the display 3, the controller 10 periodically drives the image element 4, which is located below the optical sensor 13, with the minimum and maximum values of the light intensity.

The minimum value of the light intensity can be, for example, the black value of a picture element 4, i.e. the value which the picture element 4 emits as a result of a minimum actuation of this picture element 4.

The maximum value of the light intensity can be, for example, the white value of the picture element 4, i.e. the value at which the picture element 4 emits the greatest activation of the picture element. In one display section (the brightness of which is also determined by the backlighting section), the light intensity also appears constant.

The optical sensor 13 continuously measures the light intensity of the image elements 4 in the frame of its measuring speed (which is adapted to the frame rate of the display 3). From this value, the evaluation unit 11 calculates the distance between the minimum and maximum values of the light intensity of the image element 4 and transmits this value to the controller 10. The calculation unit 15 checks: whether this value is above the lowest value previously determined. If this is the case, the spacing between the minimum and maximum values of the light intensity of the picture element 4 is sufficient and can be considered: the display unit 3 provides an image with high contrast to an observer.

However, if the spacing between the maximum and minimum values of the light intensity of the picture elements 4 lies below the previously determined minimum spacing, this phenomenon is stored in the memory unit 16 of the controller 10. The memory unit 16 thus registers all phenomena in which the spacing between the minimum and maximum values of the light intensity of the picture element 4 is lower than the previously determined minimum value. The display apparatus 1 is at least partially restarted if the number of said phenomena exceeds a previously determined frequency.

The at least partial restart of the display device 1 represents: at least a part of the electronic components and functional units (e.g. evaluation unit 11, calculation unit 15 or memory unit 16) contained in display device 1 are reset into their defined starting state. In the case of the storage unit 16, this represents, for example: the memory of the memory unit required for the display generation is drained.

In this case, the frequency can be calculated as the absolute number of phenomena and the number of phenomena for each fixed time interval. The frequency limit value can also be fixed, for example, by the user or driver of the vehicle or by the manufacturer. The display section thus monitored is capable of displaying safety-related information.

After at least partial restart of the display device 1, the image element 4 (which is arranged below the optical sensor 13) is again operated continuously with its minimum and maximum values of the light intensity. The optical sensor 13 in turn continuously measures the light intensity of the image elements 4 and forwards these values to the evaluation unit 11. The evaluation unit 11 in turn determines the distance between the minimum and maximum values of the light elements 4 and passes these values again to the calculation unit 15 of the controller 10. The calculation unit 15 checks again: whether the spacing between the minimum and maximum values of the light intensity of the picture elements 4 lies above the previously determined minimum value. In this case, it can be considered that the display unit 3 functioning is provided with an image having a high contrast.

However, if the distance between the minimum and maximum values of the measured light intensity of the image elements 4 lies below a predefined minimum distance, this is stored as a result in the memory 16. If a certain frequency of undershoots occurs again, the entire display device 1 is switched off. Here, the frequency can again be a previously determined absolute number of phenomena, but can also represent the number of phenomena per defined time interval. When the entire display device 1 is switched off, the control unit 10 gives warnings to the surroundings or to the driver of the vehicle via the acoustic interface 17. It can thus be ensured that the driver knows complete switching off of the display device.

Fig. 2 shows a flow chart which shows the course of the method according to the invention.

In a first measuring step 20, the distance between the minimum and maximum values of the light intensity of the image elements 4 is measured via the optical sensor 13 mounted on the display 3. In a checking step 21 it is checked: whether the spacing between the minimum and maximum values of the light intensity of the picture elements 4 exceeds a predetermined minimum value.

If the distance between the minimum and maximum values of the light intensity of the picture elements 4 exceeds a predefined minimum value, method step 22 is carried out. The method step 22 includes determining: the display 3 functions correctly and initiates the successive repetition of steps 20, 21 and 22.

If the distance between the minimum and maximum values of the light intensity of the picture elements 4 is below a predetermined minimum value, a checking step 30 is carried out. Checking step 30 checking: whether a known parameter affecting the brightness of the display section (e.g., an existing backlighting section) is changed. If at least one parameter affecting the brightness of the display is significantly changed, step 20 is performed. Otherwise, the measuring step 20 and the checking steps 21 and 30 are repeated so long until the frequency of undershoots determined in the accumulating step 23 is reached. Then, in a method step 24, at least a partial restart of the display device 1 is carried out.

After at least partial restart of the display device 1, a further measurement step 25 is carried out in which the distance between the minimum and maximum values of the light intensity of the image element 4 is measured via the optical sensor 13 mounted on the display 3.

In a further checking step 26: whether the spacing between the minimum and maximum values of the light intensity of the picture elements 4 exceeds a predetermined minimum value. If the distance between the minimum and maximum values of the light intensity of the picture elements 4 exceeds the predefined minimum value, a determination is again made using method step 22: the display 3 functions correctly and initiates the successive repetition of the steps 20, 21, 22.

If the distance between the minimum and maximum values of the light intensity of the picture elements 4 is below a predetermined minimum value, a checking step 31 is carried out. Checking step 31 checking: whether a known parameter affecting the brightness of the display section (e.g., an existing backlighting section) is changed. If at least one parameter affecting the brightness of the display is significantly changed, step 25 is performed. Otherwise, the measuring step 25 and the checking steps 26 and 31 are repeated so long until the determined frequency of undershoots in the accumulating step 27 is reached.

If this frequency of undershoots is reached, in method step 28, the display device 1 is switched off and an acoustic warning 29 is output to the surroundings or the driver, which warning is intended to make the switching off of the display device 1 noticeable.

Claims

1. A method for operating a display device (1) comprising a display (3) with a plurality of picture elements (4), wherein the picture elements (4) are operated as a function of operating parameters by means of the following three parameters: for picture elements-a minimum and a maximum of the light intensity and a plurality of intermediate values of the light intensity, characterized in that in at least one section of the display surface the picture elements (4) are periodically operated with their minimum and maximum values of the light intensity, the spacing between the minimum and maximum values of the light intensity is repeatedly measured, the display device (1) is at least partially restarted if the measured spacing value falls below a predefined minimum value at a predefined first frequency, and the display device (1) is switched off if the measured spacing value falls below a predefined minimum value at a predefined second frequency.

2. Method according to claim 1, characterized in that after twice falling below the lowest value, the display device (1) is at least partially restarted and the measurement is repeated again, and in that the display device (1) is switched off a number of times when falling below the lowest value.

3. Method according to claim 1, characterized in that after twice falling below a minimum value, the display device (1) is at least partially restarted and the measurement is repeated again, and in that below the minimum value the display device (1) is switched off.

4. A method as claimed in any one of claims 1 to 3, characterized in that the frequency with which the picture elements (4) are periodically operated between their minimum and maximum light intensity is less than or equal to the frame rate of the display section (3).

5. Method according to any one of claims 1 to 3, characterized in that the frame rate of the display (3) is matched to the temperature prevailing at the display (3) and thus also such a frequency is matched to the temperature prevailing at the display (3): the frequency is used to periodically run the picture element (4) between a minimum and a maximum of the light intensity of said picture element.

6. A method as claimed in any one of claims 1 to 3, characterized in that only picture elements (4) of one color are operated in sequence each.

7. Method according to any of claims 1 to 3, characterized in that the distance between the minimum and maximum of the light intensity depends on the intensity of the backlighting portion (5), the temperature present at the display portion (3) and/or the age of the display portion (3).

8. The method according to any one of claims 1 to 3, wherein the display device (1) is used in a motor vehicle.

9. Display device (1) comprising a display (3) with a plurality of picture elements (4) which can be operated as a function of a manipulated variable by means of the following three parameters: for picture elements-a minimum and a maximum of light intensity and a plurality of intermediate values of said light intensity, characterized in that:

an optical sensor (13) for light intensity measurement,

-an evaluation unit (11) for verifying: whether a predefined minimum spacing between a minimum and a maximum of the light intensity is to be observed in at least one section of the display area,

a storage unit (16) for storing the frequency at which the measured distance value between the minimum and maximum values of the light intensity falls below a predefined minimum distance, an

-a control unit (10) for periodically operating the picture elements (4) of the display (3) with their minimum and maximum light intensity values and continuously measuring the distance between the minimum and maximum light intensity values, wherein the display device (1) is at least partially restarted if the measured distance value is below a predefined minimum distance at a predefined first frequency; wherein if the measured distance value falls below a predefined minimum distance with a predefined second frequency, the display device (1) is switched off and an acoustic warning (17) is output.

10. A display device according to claim 9, wherein the display portion (3) is a liquid crystal display portion.

11. A display device according to claim 9 or 10, characterized in that the display part (3) is a display part (3) capable of developing color.

12. A display device as claimed in claim 9 or 10, characterized in that the optical sensor (13) is mounted in a covered manner on the display section (3).

13. The display device according to claim 9 or 10, wherein a temperature sensor (14) is mounted at the display section (3).

14. Display device according to claim 9 or 10, characterised in that the display device (1) is for a motor vehicle.