JP2004322886A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device which can maintain excellent visibility even when ambient brightness suddenly changes. <P>SOLUTION: The display device comprises a light emission type indicator 27 capable of changing the indication brightness, a light detection means 18 to output the detection value according to the brightness of the outside light as the detection signal X, and a control means 20 which outputs the control brightness value to be calculated based on the detection value and the adjustment value as the control signal Y and controls the indication brightness of the light emission type indicator 27. The control means 20 stores the first detection value detected by the light detection means 18 and the threshold of the detection value, and calculates the target brightness value based on the second detection value newly detected by the light detection means 18. If the first detection value is higher in brightness than the threshold, and the second detection value is lower in brightness than the threshold, the high-speed adjustment value in which the control brightness value is closer to the target brightness value than a regular value is determined as the adjustment value, and the control value based on the high-speed adjustment value is calculated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display device, and more particularly to a display device for adjusting 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 brightness of a light-emitting display device such as a fluorescent display tube according to the surrounding brightness. For example, a display device including a head-up display detects, with an optical sensor, the brightness in front of the vehicle, which is the background of a display image projected on the windshield of the vehicle, and controls the front in accordance with the detected brightness in front of the vehicle. Controls the brightness of the display image projected on the glass, so that when the front of the vehicle is bright, the display brightness is increased, and when it is dark, the display brightness is reduced so that the display is easier to see. (For example, see Patent Document 1).
[0003]
In addition, in the case where the sunshine enters in some places while the vehicle is running, if the display brightness of the display device is adjusted according to the brightness value in front of the vehicle detected by the optical sensor, the display brightness value greatly changes. Then, since the display is flickered to the driver's eyes because the display is flickered, a display device in which the flicker is reduced by providing a control unit for slowly changing the display luminance has been proposed (for example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-61-42333 [Patent Document 2]
JP-A-11-319772
[Problems to be solved by the invention]
However, in such a display device, although the display brightness can be gradually changed to reduce flickering and provide a display with improved visibility, for example, when the vehicle enters a tunnel in the daytime, the vicinity of the vehicle suddenly changes. When the brightness of the display becomes dark, it takes time until the display brightness becomes good, and during that time, the display brightness of the display image becomes too bright to be easily seen, and the driver always has excellent visibility. There was no problem.
[0006]
The present invention has been made in view of the above-described problem, and has as its object 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-mentioned problems, a display device according to the present invention outputs a light-emitting display device capable of changing display luminance and a detection value corresponding to ambient brightness as a detection signal. A display device comprising: a light detection unit; and a control unit that outputs a control luminance value calculated based on the detection value and the adjustment value as a control signal, and controls display luminance of the light-emitting display. The control means stores a first detection value detected by the light detection means and a threshold value of the detection value, and sets a target luminance value based on a second detection value newly detected by the light detection means. Calculating, if 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 has a larger change amount than normal. The high-speed adjustment value that becomes the value is the adjustment value. Determined, characterized by comprising calculating the control luminance value based on the high-speed adjustment value.
[0008]
Further, in claim 1, as in claim 2, after the control means determines the high-speed adjustment value as the adjustment value, the display luminance of the light-emitting display device adjusts the high-speed adjustment value. When the target brightness value approximates or reaches the target brightness value determined as the value, the determination that the high-speed adjustment value is the adjustment value is canceled.
Further, in claim 1, as in claim 3, after determining the high-speed adjustment value as the adjustment value, the control means determines that the first detection value is a value darker than the threshold value and When the second detection value is a value brighter than the threshold value, the determination that the high-speed adjustment value is the adjustment value is canceled.
[0010]
Further, the display device of the present invention, as described in claim 4, a light-emitting display device capable of changing the display brightness, and a light detection unit that outputs a detection value according to ambient brightness as a detection signal, A control unit that outputs a control luminance value calculated based on the detected value as a control signal, and controls a display luminance of the light-emitting display device. The detected first detection value and a threshold value of the detection value are stored, and a target luminance value is calculated based on a second detection value newly detected by the light detection unit. If the value is brighter than a threshold value and the second detection value is a value darker than the threshold value, the light-emitting display device is such that the control brightness value approximates the target brightness value in a shorter time than usual. Characterized by high speed control of
[0011]
Further, in claim 4, as set forth in claim 5, the control means may adjust the display brightness of the light-emitting display to approximate the target brightness value when the high-speed adjustment value is determined as the adjustment value. When reaching, the high-speed control is released.
[0012]
Further, in claim 4, as in claim 6, the control means is configured such that the first detection value is a value darker than the threshold value and the second detection value is a value brighter than the threshold value. In this case, the high-speed control is released.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example in which an embodiment of the present invention is applied to a vehicle head-up display will be described.
[0014]
As shown in FIG. 1, A is a display unit, and this display unit A is disposed in the dashboard 1 of the vehicle, and the display light L projected by the display unit A is applied to the viewer 3 by the windshield 2. Reflected in the direction. The observer 3 can observe the virtual image 4 while superimposing it on the scenery.
[0015]
FIG. 2 is a sectional view of the display unit A. Reference numeral 5 denotes a light-emitting element composed 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. Reference numeral 7 denotes a circuit board, and the circuit board 7 is connected to the light emitting element 5 and the liquid crystal display element 6. A microcomputer described later is mounted on the circuit board 7.
[0016]
Reference numeral 11 denotes a housing. The housing 11 accommodates the light emitting element 5, the circuit board 7, and the like. An opening 12 from which the display light L is emitted is provided in the housing 11, and a light-transmitting cover 13 made of a light-transmitting resin (eg, acrylic) is provided in the opening 12. A reflecting mirror 14 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 to prevent external light such as sunlight from being incident on the liquid crystal display element 6 and making the virtual image 4 difficult to see (washout). ing. The light shielding wall 15 is provided with a through hole 16 formed at a position facing an optical sensor described later. Reference numeral 17 denotes an optical sensor, which detects light transmitted through the translucent cover 13 and passed through the through hole 16. The optical sensor 17 is provided behind the light blocking wall 15 and is connected to the circuit board 7.
[0017]
Next, 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 light detecting means, which comprises 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. Note that the detection value x is an integer and is set in accordance with the level of the brightness signal W, and a larger value indicates a brighter state.
[0018]
The control means 20 is mainly composed of a microcomputer, and based on a detection signal X from the light detection means 18, a CPU (central processing unit) 21 as means for performing various arithmetic processing, A read / write rewritable RAM 22 for temporarily storing processing results and a read-only program memory ROM 23 for storing a control program are provided. Further, the control means 20 includes an input / output interface (not shown) for electrically connecting to the light detection means 18 and a drive circuit. Further, the control means 20 has a storage unit 24 such as an EEPROM or a backup RAM for storing a data table for determining a target luminance value, which will be described later, and a threshold value or an adjustment value of a detection value.
[0019]
Further, the CPU 21 calculates a target luminance value of the light emitting element 5 according to the detection signal X from the light detecting means 18 according to the program data stored in the ROM 23, and uses the target luminance value as a control signal Y to the drive circuit 25. Output, and 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 having a polarizing member attached to the front and rear surfaces of a liquid crystal cell in which liquid crystal is sealed in a pair of translucent substrates, via a driving circuit 26. . The RAM 22 temporarily stores (stores) a detection value (first detection value) x1 detected last time. The light emitting element 5 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 new second detection value x2 as a detection value x from the detection signal X generated by the light detection means 18. (Step S1).
[0022]
The control means 20 calculates a target luminance value t based on the second detection value x2 input in step S1 (step S2). Note that the target luminance 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 in correspondence with the brightness in front of the vehicle (brightness based on the detection value x) and the display brightness of the display device which is easy for the driver to visually recognize at this brightness, and is stored in the storage unit 24. Have been.
[0023]
The control means 20 compares the first detection value x1 and the second detection value x2 stored in the RAM 22 with a threshold s (step S3). The threshold value s is stored in the storage unit 24. When the detection value x is larger than the threshold value s, it is determined that the brightness in front of the vehicle is the normal brightness at night or in a tunnel. It is set as shown. In step S3, when the first detection value x1 is smaller than the threshold value s and the second detection value x2 is equal to or larger than the threshold value s, 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 for calculating 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 amount of the luminance change as the adjustment value w (step S6), and Is "1", a high-speed adjustment value w2 having a large change in luminance change is determined as the adjustment value w (step S7). 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 change amount of 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 to become a value.
[0025]
The control means 20 calculates the following adjustment formula using the determined adjustment value w, the target brightness value t obtained from the second detection value x2, and the reference brightness value z stored in the RAM 22. The control luminance value y is calculated (step S8).
y = z + ((t−z) / w)
Note that the reference luminance value z is the control luminance value previously output as the control signal Y. The control luminance value y is set to be a value between the target luminance value t and the reference luminance value z. Further, when the control luminance value y is calculated using the high-speed adjustment value w2, the difference from the target luminance value t is smaller than when the control luminance value y is calculated using the normal adjustment value w1.
[0026]
Further, the control means 20 outputs the control luminance value y obtained in step S8 to the drive circuit 25 as a control signal Y (step S9). The drive circuit 25 performs PWM control based on the control signal Y to adjust the display luminance of the light emitting element 5 so as to emit light at the control luminance value y. 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, and The difference between the control luminance value y and the control luminance value y is compared (step S10). If the absolute value of the difference is equal to or smaller than the predetermined value a (| by− ≦ a), the display luminance of the light-emitting element 5 is compared with the comparative luminance value. The flag is set to "0" when it is determined that it is close to b (step S11). If the absolute value of the difference between the comparative luminance value b and the control luminance value y is larger than the predetermined value a (| by−> a), the display luminance of the light emitting element 5 approximates the target luminance value t. It is determined that the flag has not been set, and the flag is maintained at "1". Therefore, after the high-speed adjustment value w2 is determined as the adjustment value w, if the display luminance of the light emitting element 5 is close to the target luminance value t when the high-speed adjustment value w2 is determined as the adjustment value w, the high-speed adjustment is performed. When the determination of the value w2 as 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 changed to The determination as the adjustment value w will be maintained.
[0027]
Note that in step S10, the flag may be set to "0" when the display luminance of the light emitting element 5 reaches the target luminance value t when the flag is set to "1".
[0028]
The control means 20 substitutes the second detection value x2 for the first detection value x1 to update the first detection value x1, and substitutes the control luminance value y for the reference luminance value z to substitute for 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 the display is performed at a display brightness with good visibility according to the brightness in front of the vehicle. The display device is capable of performing the following operations. Further, by calculating the control luminance value y using the adjustment value w, the display luminance can be smoothly changed, and the flicker of the display image 4 can be reduced. When the control luminance value y is calculated using the acceleration adjustment value w2, the control luminance value y has a large change amount from the reference luminance value z, and therefore approximates the comparative luminance value b in a short time.
[0030]
Such a display device includes a light-emitting display device 27 capable of changing display luminance, a light detection unit 18 that outputs a detection value x corresponding to the surrounding brightness as a detection signal X, and a detection value x and an adjustment value w. Control means 20 for outputting a control luminance value y calculated based on the control luminance signal y as a control signal Y and controlling the display luminance of the light-emitting display 27. The first detection value x1 and the threshold value s of the detection value x are stored, and the target luminance value t is calculated based on the second detection value x2 newly detected by the light detection means 18. When the detection value x1 is a value brighter than the threshold value s and the second detection value x2 is a value darker than the threshold value s, the flag is set to “1” and the control luminance value y changes more than normal. The high-speed adjustment value w2 that gives a large value of Determine Te, formed by calculating the control luminance value y based on this fast adjustment value w2. In addition, 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 is close to the target luminance t when the high-speed adjustment value w2 is determined as the adjustment value w. The flag is set to “0”, and the determination that the high-speed adjustment value w2 is the adjustment value w is released.
[0031]
Therefore, in such a display device, when the surrounding brightness suddenly becomes dark, the control brightness value y having a large amount of change from the reference brightness value z is calculated based on the high-speed adjustment value w2. Even in the case where the brightness suddenly decreases, it does not take a long time until the display brightness becomes good as in the past, and the display brightness of the display image is too bright to be easily seen in a short time. Thus, it is possible to perform display with good visibility by the display luminance following the change in brightness.
[0032]
In the embodiment of the present invention, the above-described head-up display for a vehicle has been described as an example. However, the present invention is not limited to this, and the configuration is not limited as long as a similar effect can be obtained. For example, the present invention may be applied to a light-emitting display device equipped with an organic EL element or the like. Further, the present invention may be applied to a liquid crystal display used as a display device of a navigation device.
[0033]
Further, in the above-described embodiment, an example in which the adjustment value w is determined using the data table has been described as an example. However, the present invention is not limited to this. May be obtained by a predetermined calculation based on
[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” to set the high-speed adjustment value w2. Although the determination of the adjustment value w is canceled, the present invention determines that the first detection value detected last time is a value darker than the threshold value and newly detected after the high-speed adjustment value is determined as the adjustment value. When the detected second detected value is a value 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 the vehicle leaves the tunnel.
[0035]
Further, in the embodiment described above, when the surrounding 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 is also applicable to a display device that does not use an adjustment value. As a control method, the first detection value detected by the light detection unit and a threshold value of the detection value are controlled. Means, a target luminance value is calculated based on a second detection value newly detected by the light detection means, and the first detection value is a value 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 a high speed so that the control luminance value approximates the target luminance value in a shorter time than usual. Such a display device can reduce the display brightness of the light-emitting element 5 in a short time when the brightness around the vehicle suddenly becomes dark. And the display device has good visibility.
[0036]
【The invention's effect】
The present invention provides a light-emitting display device capable of changing display luminance, light detection means for outputting a detection value corresponding to brightness as a detection signal, and calculating a control luminance value of the light-emitting display device based on the detection value. Control means for controlling the display brightness of the light-emitting display based on the control brightness value, even if the surrounding brightness changes rapidly, the visibility is good. A simple display device can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a display device mounted on a vehicle according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the display unit according to 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]
Reference Signs List 5 light emitting element 6 liquid crystal display element 18 light detecting means 20 control means 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 (6)

A light-emitting display device capable of changing display brightness, 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 Control means for outputting as a signal and controlling the display luminance of the light-emitting display device, comprising:
The control unit stores a first detection value detected by the light detection unit and a threshold value of the detection value, and calculates a target luminance value based on a second detection value newly detected by the light detection unit. When the first detection value is a value brighter than the threshold value and the second detection value is a darker value than the threshold value, the control luminance value is a value having a larger change amount than normal. A display device comprising: determining a high-speed adjustment value that satisfies the following as the adjustment value; and calculating the control luminance value based on the high-speed adjustment value. The control means, after determining the high-speed adjustment value as the adjustment value, when the display luminance of the light emitting display approximates or reaches the target luminance value when the high-speed adjustment value is determined as the adjustment value. The display device according to claim 1, wherein the determination that the high-speed adjustment value is the adjustment value is canceled. The control means, after determining the high-speed adjustment value as the adjustment value, when the first detection value is a value darker than the threshold and the second detection value is a value brighter than the threshold The display device according to claim 1, wherein the determination that the high-speed adjustment value is set as the adjustment value is canceled. A light-emitting display device capable of changing display brightness, light detection means for outputting a detection value corresponding to the surrounding brightness as a detection signal, and a control brightness value calculated based on the detection value being output as a control signal, Control means for controlling the display brightness of the light-emitting display, a display device comprising:
The control unit stores a first detection value detected by the light detection unit and a threshold value of the detection value, and calculates a target luminance value based on a second detection value newly detected by the light detection unit. When 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 a normal value in the target luminance value. A display device characterized in that the light-emitting display device is controlled at a high speed so as to approximate the following. 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 adjustment value is determined as the adjustment value. The display device according to claim 4. The control means cancels the high-speed control when the first detection value is a value darker than the threshold value and the second detection value is a value brighter than the threshold value. 5. The display device according to 4.

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