JP4295001B2 - Display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device, and more particularly to a display device that adjusts the luminance of a light emitting display.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a display device that automatically adjusts the luminance of a light emitting display such as a fluorescent display tube according to the ambient brightness. For example, a display device composed of a head-up display detects the brightness in front of the vehicle, which is the background of the display image projected on the windshield of the vehicle, with an optical sensor, and detects the front according to the detected brightness in front of the vehicle. Controls the brightness of the display image projected on the glass, thereby increasing the display brightness when the front of the vehicle is bright, and reducing the display brightness when it is dark so that the display is easy to see. (For example, refer to Patent Document 1).
[0003]
In addition, when the sun is coming in from place to place while the vehicle is running, the display brightness value changes greatly if the display brightness of the display device is adjusted according to the brightness value in front of the vehicle detected by the light sensor. Since the display feels flickering to the driver's eyes because it is repeated, a display device that reduces flickering by providing a control means for gently changing the display brightness has been proposed (for example, Patent Document 2).
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. 61-42333 [Patent Document 2]
Japanese Patent Laid-Open No. 11-311972
[Problems to be solved by the invention]
However, in such a display device, it is possible to provide a display with improved visibility by reducing flickering slowly, but suddenly around the vehicle such as when the vehicle enters a tunnel in the daytime, for example. When the brightness of the vehicle becomes dark, it takes time until the display brightness becomes good. During this time, the display brightness of the display image becomes too bright and difficult to see, and it is not necessarily excellent for the driver. There was no problem.
[0006]
Therefore, the present invention has been made paying attention to the above-described problem, and an object of the present invention is to provide a display device with good visibility even when the surrounding brightness suddenly becomes dark.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a display device of the present invention is a light emitting display capable of changing display luminance, a light detection means for outputting a detection value according to ambient brightness as a detection signal, and the detection value. In the display brightness control of the light emitting display that outputs a control brightness value calculated based on the adjustment value as a control signal, a first detection value detected by the light detection means and a threshold value of the detection value are obtained. Storing a target brightness value based on the second detection value newly detected by the light detection means, wherein the first detection value is brighter than the threshold value, and the second detection value is When the value is darker than the threshold value, a high-speed adjustment value is determined as the adjustment value so that the control luminance value has a larger change amount than normal, and the control luminance value based on the high-speed adjustment value And the high speed adjustment After the value is determined as the adjustment value, the high-speed adjustment value is adjusted when the first detection value is darker than the threshold and the second detection value is brighter than the threshold. and characterized in that it comprises a control means for canceling a decision that the values, the.
[0008]
In addition, after determining the high-speed adjustment value as the adjustment value, the control means approximates or reaches the target luminance value when the display luminance of the light-emitting display unit determines the high-speed adjustment value as the adjustment value. In this case, the determination using the high-speed adjustment value as the adjustment value is canceled.
[0010]
The display device of the present invention includes a light-emitting display capable of changing display brightness, light detection means for outputting a detection value according to ambient brightness as a detection signal, and control brightness calculated from the detection value. In display luminance control of the light emitting display that outputs a value as a control signal, the first detection value detected by the light detection means and the threshold value of the detection value are stored, and newly detected by the light detection means A target luminance value is calculated based on the second detected value, and when the first detected value is brighter than the threshold and the second detected value is darker than the threshold, the control luminance The light emitting display is controlled at high speed so that the value approximates the target luminance value in a shorter time than normal, and the first detection value is darker than the threshold and the second detection The value is brighter than the threshold value If, and characterized in that it comprises a control means for releasing the high-speed control.
[0011]
Further, the control means cancels the high-speed control when the display luminance of the light emitting display approximates or reaches the target luminance value when the high-speed control is determined.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the embodiment of the present invention applied to a vehicle head-up display will be described as an example.
[0014]
As shown in FIG. 1, A is a display unit. The display unit A is disposed in the dashboard 1 of the vehicle, and the display light L projected by the display unit A is transmitted to the observer 3 by the windshield 2. Reflected in the direction. The observer 3 can observe the virtual image 4 superimposed on the landscape.
[0015]
FIG. 2 is a cross-sectional view of the display unit A. Reference numeral 5 denotes a light emitting element made of a light emitting diode. The light emitting element 5 has a liquid crystal display element 6 on the illumination direction side and emits display light L. A circuit board 7 is connected to the light emitting element 5 and the liquid crystal display element 6. A microcomputer to be described later is mounted on the circuit board 7.
[0016]
Reference numeral 11 denotes a housing, in which the light emitting element 5, the circuit board 7, and the like are accommodated. An opening 12 through which the display light L is emitted is provided in the housing 11, and a translucent cover 13 made of a translucent resin (for example, acrylic) is disposed in the opening 12. Reference numeral 14 denotes a reflecting mirror that reflects the display light L in the direction of the opening 12. Reference numeral 15 denotes a light shielding wall. The light shielding wall 15 is formed integrally with the housing 11, and prevents external light such as sunlight from entering the liquid crystal display element 6 and making it difficult to see the virtual image 4 (washout). ing. The light shielding wall 15 is provided with a through hole 16 formed at a location facing an optical sensor described later. Reference numeral 17 denotes an optical sensor. The optical sensor 17 detects light transmitted through the translucent cover 13 and passing through the through hole 16. The optical sensor 17 is disposed behind the light shielding wall 15 and is connected to the circuit board 7.
[0017]
Next, the adjustment of the luminance of the light emitting element 5 will be described based on the block diagram shown in FIG. Reference numeral 18 denotes a light detection means, and the light detection means 18 includes a light sensor 17 and an A / D converter 19. The A / D converter 19 converts the brightness signal W output from the optical sensor 17 as a detection value x, and outputs the detection value x as a detection signal X to the control means 20. The detection value x is an integer and is set according to the level of the brightness signal W. A larger value indicates a brighter state.
[0018]
The control means 20 is mainly composed of a microcomputer, and based on the detection signal X from the light detection means 18, a CPU (central processing unit) 21 as means for performing various arithmetic processes and arithmetic operations in the CPU 21. A RAM 22 that is a readable / rewritable working memory that temporarily stores processing results and a ROM 23 that is a read-only program memory that stores control programs are provided. Further, the control means 20 includes an input / output interface (not shown) for electrical connection to the light detection means 18 and a drive circuit. In addition, the control unit 20 includes a storage unit 24 such as a data table for determining a target luminance value, which will be described later, and an EEPROM or backup RAM for storing a threshold value or adjustment value of a detection value.
[0019]
Further, the CPU 21 calculates a target luminance value of the light emitting element 5 in accordance with the detection signal X from the light detection means 18 according to the program data stored in the ROM 23, and uses this target luminance value as a control signal Y for the drive circuit 25. The display brightness of the light emitting element 5 can be adjusted. Further, the control means 20 can drive and control the liquid crystal display element 8 formed by adhering a polarizing member to the front and back surfaces of a liquid crystal cell in which liquid crystal is sealed in a pair of translucent substrates via a drive circuit 26. . The RAM 22 temporarily stores (stores) the previously detected detection value (first detection value) x1. The light emitting element 27 and the liquid crystal display element 8 constitute a light emitting display 27.
[0020]
Next, a control method by the control means 20 until the control signal Y is output will be described based on the flowchart shown in FIG.
[0021]
The control means 20 inputs a second detection value x2 as a detection value x from the detection signal X emitted by the light detection means 18. (Step S1).
[0022]
The control means 20 calculates the target luminance value t based on the second detection value x2 input at step S1 (step S2). The target brightness value t is determined by referring to a data table set in advance corresponding to the second detection value x2 and extracting a value corresponding to the second detection value x2. . This data table is set in advance according to the correspondence between the brightness in front of the vehicle (brightness based on the detected value x) and the display brightness of the display device that is easily visible to the driver at this brightness, and is stored in the storage unit 24. Has been.
[0023]
The control means 20 compares the first detection value x1 and the second detection value x2 stored in the RAM 22 with the threshold value s (step S3). The threshold value s is stored in the storage unit 24. When the detected value x is larger than the threshold value s, the brightness in front of the vehicle is normal brightness at night or in a tunnel. Set as shown. When the first detection value x1 is smaller than the threshold value s and the second detection value x2 is greater than or equal to the threshold value s in step S3, the control unit 20 sets the flag to “1” (flag = 1, step S4). ).
[0024]
The control means 20 determines the state of the flag (step S5) and determines an adjustment value (variable) w used to calculate the control luminance value y. That is, when the flag is “0” (flag = 0), the control means 20 determines the normal adjustment value w1 having a small change in luminance as the adjustment value w (step S6), and the flag Is “1”, the high-speed adjustment value w2 having a large change amount of the luminance change is determined as the adjustment value w (step S7). Note that the normal adjustment value w1 and the high-speed adjustment value w2 are stored in the storage unit 24, and the high-speed adjustment value w2 has a larger amount of change in the control luminance value y from a reference luminance value described later than the normal adjustment value w1. It is set with a value that prompts it to be a value.
[0025]
The control means 20 has the following arithmetic expression using the determined adjustment value w, the target luminance value t obtained from the second detection value x2, and the reference luminance value z stored in the RAM 22. A control luminance value y is calculated (step S8).
y = z + ((t−z) / w)
The reference luminance value z is a control luminance value output as the previous control signal Y. Further, the control luminance value y is set to be a value between the target luminance value t and the reference luminance value z. In addition, when the control brightness value y is calculated using the high-speed adjustment value w2, the difference from the target brightness value t is smaller than that calculated using the normal adjustment value w1.
[0026]
Further, the control means 20 outputs the control luminance value y obtained in step S8 as a control signal Y to the drive circuit 25 (step S9). Note that the drive circuit 25 performs PWM control based on the control signal Y, thereby adjusting the display luminance of the light emitting element 5 to emit light at the control luminance value y. In addition, when the flag is “1”, the control unit 20 stores the target luminance value t when the flag is “1” in the RAM 22 as the comparative luminance value b. When the difference from the control luminance value y is compared (step S10) and the absolute value of the difference is equal to or less than a predetermined value a (| by− ≦ a), the display luminance of the light emitting element 5 is the comparative luminance value. It is determined that the value is close to b, and the flag is set to “0” (step S11). When the absolute value of the difference between the comparative brightness value b and the control brightness value y is larger than the predetermined value a (| by−> a), the display brightness of the light emitting element 5 approximates the target brightness value t. It is determined that the flag is not set, and the flag is maintained at “1”. Therefore, after the high-speed adjustment value w2 is determined as the adjustment value w, when the display luminance of the light emitting element 5 approximates the target luminance value t when the high-speed adjustment value w2 is determined as the adjustment value w, the high-speed adjustment value When the determination that the value w2 is the adjustment value w is canceled and the display luminance of the light emitting element 5 does not approximate the target luminance value t when the high-speed adjustment value w2 is determined as the adjustment value w, the high-speed adjustment value w2 is set. The determination of the adjustment value w is maintained.
[0027]
In step S10, when the display brightness of the light emitting element 5 reaches the target brightness value t when the flag is “1”, the flag may be set to “0”.
[0028]
Further, the control means 20 updates the first detection value x1 by substituting the second detection value x2 into the first detection value x1, and substitutes the control luminance value y into the reference luminance value z. The value z is updated (step S12).
[0029]
By repeating the processing from step S1 to step S12, the display brightness of the light-emitting display 27 is automatically adjusted so that display is performed with good visibility according to the brightness in front of the vehicle. The display device can be used. Further, by calculating the control luminance value y using the adjustment value w, the display luminance can be smoothly changed, and the flickering of the display image 4 can be reduced. In addition, when the control luminance value y is calculated using the acceleration adjustment value w2, the amount of change from the reference luminance value z becomes a large value, and therefore approximates to the comparative luminance value b in a short time.
[0030]
Such a display device includes a light emitting display 27 that can change display brightness, a light detection means 18 that outputs a detection value x corresponding to ambient brightness as a detection signal X, and a detection value x and an adjustment value w. The control device 20 outputs a control luminance value y calculated based on the control signal Y as a control signal Y and controls the display luminance of the light-emitting display 27. The control device 20 is a light detection device 18. The first detection value x1 detected by the first detection value and the threshold value s of the detection value x are stored, the target luminance value t is calculated from the second detection value x2 newly detected by the light detection means 18, and the first When the detection value x1 is brighter than the threshold value s and the second detection value x2 is darker than the threshold value s, the flag is set to “1” and the control luminance value y is changed from the normal amount. A high-speed adjustment value w2 that becomes a large value of Determine Te, formed by calculating the control luminance value y based on this fast adjustment value w2. Further, after determining the high-speed adjustment value w2 as the adjustment value w, the control unit 20 determines that the display luminance of the light emitting element 5 approximates the target luminance t when the high-speed adjustment value w2 is determined as the adjustment value w. The determination that the flag is set to “0” and the high-speed adjustment value w2 is the adjustment value w is canceled.
[0031]
Accordingly, when the ambient brightness suddenly becomes dark, such a display device calculates a control brightness value y having a large amount of change from the reference brightness value z based on the high-speed adjustment value w2. Even when the brightness suddenly becomes dark, it does not take time to achieve good display brightness as in the past, and the display brightness of the display image is too bright and difficult to see in a short time. Thus, it becomes possible to display with good visibility by the display brightness following the change in brightness.
[0032]
In the embodiment of the present invention, the above-described vehicle head-up display has been described as an example. However, the present invention is not limited to this, and the configuration thereof can achieve the same effect. What is necessary is just to be applicable to the light emission type display apparatus carrying an organic EL element etc., for example. Moreover, you may adapt to the liquid crystal display used as a display apparatus of a navigation apparatus.
[0033]
In the above-described embodiment, the adjustment value w is determined using the data table as an example. However, the present invention is not limited to this, and the reference brightness value, the detection value, May be obtained by a predetermined calculation.
[0034]
In the above-described embodiment, after the high-speed adjustment value w2 is determined as the adjustment value w, when the display luminance of the light emitting element 5 approximates the target luminance t, the flag is set to “0” and the high-speed adjustment value w2 is set. The determination of the adjustment value w was canceled, but in the present invention, after determining the high-speed adjustment value as the adjustment value, the first detection value detected last time is darker than the threshold and newly detected If the second detected value is brighter than the threshold value, the determination that the high-speed adjustment value is the adjustment value may be canceled. Such a display device is suitable for canceling the determination that the high-speed adjustment value is the adjustment value when exiting the tunnel.
[0035]
Further, in the above-described embodiment, when the ambient brightness suddenly becomes dark, the display brightness of the light emitting element 5 is adjusted by calculating the control brightness value y based on the detection value x and the adjustment value w. However, the present invention can also be applied to a display device that does not use an adjustment value. As a control method thereof, the first detection value detected by the light detection means and the threshold value of the detection value are controlled. And a target brightness value is calculated from the second detection value newly detected by the light detection means, the first detection value is brighter than the threshold value, and the second detection value is When the value is darker than the threshold value, the light emitting element 5 is controlled at high speed so that the control luminance value approximates the target luminance value in a shorter time than normal. Such a display device can weaken the display brightness of the light emitting element 5 in a short time when the brightness around the vehicle suddenly becomes dark, so that the display brightness of the display image is too bright and difficult to see for a short time. Thus, a display device with good visibility can be obtained.
[0036]
【The invention's effect】
The present invention provides a light emitting display capable of changing display luminance, a light detection means for outputting a detection value corresponding to brightness as a detection signal, and a control luminance value of the light emitting display based on the detection value. And a control means for controlling the display brightness of the light-emitting display device based on the control brightness value, wherein the visibility is good even when the ambient brightness changes abruptly Display device can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a display device mounted on a vehicle in an embodiment of the present invention.
FIG. 2 is a cross-sectional view of a display unit showing the embodiment.
FIG. 3 is a block diagram showing the embodiment.
FIG. 4 is a flowchart showing a processing procedure of a control unit in the embodiment.
[Explanation of symbols]
5 Light-Emitting Element 6 Liquid Crystal Display Element 18 Light Detection Unit 20 Control Unit 22 RAM
23 ROM
24 storage unit 27 light emitting display t target luminance value w adjustment value w2 high-speed adjustment value x detection value x1 first detection value x2 second detection value y control luminance value z reference luminance value X detection signal Y control signal

Claims (4)

A light emitting display capable of changing display brightness, a light detection means for outputting a detection value corresponding to ambient brightness as a detection signal, and a control brightness value calculated based on the detection value and the adjustment value In the display luminance control of the light emitting display that is output as a signal, the first detection value detected by the light detection means and the threshold value of the detection value are stored, and the first detection value newly detected by the light detection means is stored. A target luminance value is calculated based on the second detection value, and when the first detection value is brighter than the threshold and the second detection value is darker than the threshold, the control luminance value Is determined as the adjustment value, the control brightness value is calculated based on the high-speed adjustment value, and the high-speed adjustment value is calculated as the adjustment value. After determining the first When detection value is dark than the threshold value and the second detection value is brighter than the threshold, provided with a control means for releasing the decision to the high-speed adjustment value and said adjusted value display device characterized by comprising.   The control means, after determining the high-speed adjustment value as the adjustment value, when the display brightness of the light emitting display approximates or reaches the target brightness value when the high-speed adjustment value is determined as the adjustment value The display device according to claim 1, wherein the determination using the high-speed adjustment value as the adjustment value is canceled. A light emitting display capable of changing display brightness, a light detection means for outputting a detection value according to ambient brightness as a detection signal, and the light emission for outputting a control brightness value calculated from the detection value as a control signal In the display brightness control of the type display, the first detection value detected by the light detection means and the threshold value of the detection value are stored, and the target is determined by the second detection value newly detected by the light detection means. When a luminance value is calculated, and the first detection value is a value brighter than the threshold value and the second detection value is a value darker than the threshold value, the control luminance value is shorter than normal time. The light emitting display is controlled at high speed so as to approximate the target luminance value, the first detection value is darker than the threshold value, and the second detection value is brighter than the threshold value. The high-speed control Display device comprising a control means, to become comprise for.   The said control means cancels | releases the said high speed control, when the display brightness | luminance of the said light emission type display apparatus approximates or reaches | attains the said target luminance value at the time of determining the said high speed control. Display device.

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