JPH07234656A - Display device - Google Patents

Abstract

PURPOSE:To secure proper visibility at all times by optimizing the luminance of an on-vehicle display unit corresponding to variation in the quantity of ambient light. CONSTITUTION:The ambient light quantity level of the display unit is detected (step 20) and when the quantity of the light varies (step 21), the time function of the light quantity variation is calculated (step 22). A table 28 contains the optimum display luminance of the display unit set by previously measuring and estimating the time function of variation in the pupil opening extent of a viewer corresponding to the time function of the quantity of the light. The optimum display luminance corresponding to the time function of the current variation in the quantity of light is read out (step 24) by referring to the table 28 to control the display unit (step 25).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a display control device for controlling display brightness of various display devices installed in a vehicle compartment.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram of an automobile telephone set installed in a vehicle disclosed in Japanese Patent Laid-Open No. 56-71343. In the figure, the brightness control line 10 is connected to a vehicle battery (not shown) via a light switch (not shown), and when the light switch is turned on, a battery voltage is applied to the brightness control line 10. It

When a battery voltage is applied to the brightness control line 10, the microcomputer 8 controls the display of the display 9 via the display drive circuit and the lighting control of the illumination lamp 12 via the lamp drive circuit 13. To do.

When the light switch is off, the battery voltage is not applied to the brightness control line 10, the display brightness of the display 9 is not controlled, and the lighting lamp 12 is not controlled to be turned on.

As described above, in the conventional vehicle interior display device, a manual dimmer circuit for controlling the light quantity of the display device, the illumination lamp, and the display backlight in conjunction with the light switch of the vehicle, and the peripheral device of the display device. An automatic dimmer circuit is used that measures the amount of light and switches the amount of light of a display or a backlight using a certain amount of light as a threshold.

[0006]

With such a conventional display control system, it is difficult to secure good visibility in a wide luminance range from direct sunlight irradiation to darkness. Further, there is a drawback in that the brightness of the display device cannot follow the temporal change of the pupil of the viewer when the light intensity changes drastically in and out of the tunnel.

An object of the present invention is to automatically control the light quantity of the display and the backlight so as to detect the temporal fluctuation of the light quantity around the display and to cope with the temporal fluctuation of the pupil opening amount of the viewer. It is to provide a display device that can be performed.

Another object of the present invention is to provide a display device capable of ensuring appropriate visibility in a wide luminance range from direct sunlight irradiation to darkness.

[0009]

According to the present invention, a display means for displaying a character or a figure, and a light detection means for detecting a light quantity around the display means and generating a detection signal corresponding to the light quantity. A light quantity change time function calculating means for calculating a time function of the light quantity change in response to the change of the detection signal, and a time function of a change in the pupil opening amount of the viewer corresponding to the calculated light quantity change time function. And a display control unit that controls the display brightness of the display unit according to the determined display brightness. A display device is obtained.

[0010]

[Operation] When the amount of light around the display device in the vehicle changes,
The time function of this change is obtained, and the time function of the change in the pupillary aperture of the viewer corresponding to this function is estimated (measured) in advance to determine the display brightness of the set display. Even when the vehicle goes in and out of the tunnel, the display brightness can be controlled appropriately by following the pupil opening of the viewer.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of an embodiment of the present invention. The display 1 displays characters, figures, etc., and for example, a fluorescent display is used. The display drive circuit 2 controls the display brightness of the display 1 according to a command from the CPU 3.

A photosensor 4, which is a photodetector, is provided to detect the brightness around the display 1, and is composed of a phototransistor. The photo sensor 4 is installed in the vicinity of the display 1 without being affected by the light emitted by the display 1 in the vehicle interior. The photodetection signal from the photosensor 4 is amplified by the photosensor amplifier 5, and the A / D
The level of the (analog / digital) converter 6 is set to a possible level.

The photodetection information converted into a digital signal by the A / D converter 6 is supplied to the CPU 3 and processed by the processing procedure according to FIG. By this processing, the display brightness of the display device 1 is always optimally controlled according to the change in the ambient light amount.

Referring to FIG. 2, the photo sensor 4 constantly detects the amount of ambient light, and this detection signal is sent to the amplifier 5, A
It is constantly supplied to the CPU 3 via the / D converter 6 (step 20). Now, if a car enters a tunnel, the amount of light changes and the detection signal also changes accordingly.
This change in the amount of light is output as a change in the detection signal of the photo sensor 4, and the digital signal of the A / D converter 6 also changes accordingly.

When this variation in light quantity is detected (step 2
1) In response, the absolute level of the ambient light quantity and the time function of its variation are calculated (step 22). The fluctuation time function of the ambient light amount is calculated by the light amount absolute value level and the differential value which is its temporal change.

Since the time function of the pupil opening amount of the viewer is uniquely determined corresponding to this light amount fluctuation time function,
The light quantity variation time function and the pupillary opening time function are stored in the function table 26 in advance in a one-to-one relationship. And step 2
This table 2 is obtained by the light amount fluctuation time function calculated in 2.
6, the pupillary opening time function uniquely determined by this light amount fluctuation time function is read out, and the pupillary opening time function is determined (step 23).

The display 1 corresponds to this pupil opening time function.
Since the optimum brightness of the pupil opening amount time function and the optimum brightness can be determined in advance,
It is stored in 7 in one-to-one. Then, the table 27 is referred to by the pupillary opening time function determined in step 23, the optimum brightness uniquely determined by this pupillary opening time function is read, and the optimum brightness of the display 1 is determined (step 24). .

According to the thus determined optimum brightness, CP
U3 controls the brightness of the display 1 via the display drive circuit 2 (step 25).

FIG. 3 shows an example of the temporal change of the light amount and the corresponding temporal change of the pupil opening amount of the viewer, and further, an example of the optimum control of the display brightness with respect to the temporal change of the pupil opening amount. And is shown.

If the vehicle enters the tunnel from a bright place at time t1, the amount of ambient light suddenly changes from bright to dark. During a few seconds from time t1 to t2, a dark illusion occurs and the pupil rapidly opens to a certain opening. Therefore, this period T
1 rapidly reduces the display brightness of the display in response to this rapid pupil opening.

From time t2 onward, the pupil gradually opens, so during this period T2, the display brightness is gradually reduced in accordance with the slow opening of the pupil.

At time t3, when a car exits the tunnel, the amount of ambient light suddenly changes from dark to bright. From time t3
For several seconds at t4, the pupil is in a bright and dazzling state, and the pupil rapidly closes to a certain degree of opening. Therefore, during this period T3, the display brightness rapidly increases according to the closed state of the pupil.

In human vision, it is known that the dark adaptation when the surroundings change from light to dark requires several minutes to several tens of minutes, and therefore the optimum display brightness also corresponds to the dark adaptation in the period T2. It is gradually controlled as shown in FIG. On the other hand, the light adaptation when the surroundings change from dark to light is 1
It is known that the process is completed within about a minute, and accordingly, the optimum display brightness is controlled quickly as shown in the period T3 according to the light adaptation.

Since the three temporal change characteristics (functions) shown in FIG. 3 are uniquely determined, these characteristics are stored in the function tables 26 and 27 in advance. Function table 2
In 6, the fluctuation time function of the pupil opening amount with respect to the fluctuation time function of the light amount is stored. Further, the display brightness table 27 stores the fluctuation time function of the optimum display brightness with respect to the fluctuation time function of the pupil opening amount.

A ROM (Read Only Memory) can be used for these tables 26 and 27. A variable time function of the light amount is supplied to the address input of the table 26, and a change of the pupil opening amount to the address input of the table 27. A time function is provided.

There are many possible ways of changing the amount of light other than those shown in the uppermost part of FIG. 3, but in reality, it is impossible to completely cope with all of these changes in the amount of light.
Therefore, representatively, for example, 4 to 8 ways of changing the amount of light are set in advance, and the pupil opening amount variation time function is actually measured in correspondence with each of these 4 to 8 ways of changing the amount of light.
Store in 6. Further, the optimum value of the display brightness of the display device is also measured and stored in the table 27 in correspondence with each of the 4 to 8 types of the pupillary opening variation time function.

As described above, when the light quantity change modes are typically summarized in 4 to 8 ways, a certain light quantity change mode is 4 to 8 ways.
To determine which change mode of the street to belong to, the following is performed.

That is, when the light quantity variation time function is obtained (step 22), it is obtained using the absolute level of the device and its time variation (differential value). This light quantity variation time function is expressed by m bits. In this case, using the combination pattern of the upper n bits (0 <n <m) of the m bits, 2 ⁿ (4 to 8 when n = 2 to 3) bit patterns are input to the address of the function table 26. It should be done.

In the example of FIG. 2, the optimum display brightness is determined using two tables, the function table 26 and the display brightness table 27. However, these two tables are combined into one and only the table 28 is used. An example of this is shown in FIG.

In the example of FIG. 4, the pupil opening amount variation time function determining step 23 of FIG. 2 is omitted, and instead, the display brightness information for the light amount variation time function is stored in the table 28 in advance. In this case, it is assumed that the optimum value is set in advance by estimating the change function of the viewer's pupil opening amount corresponding to the display brightness and the light amount change time function stored in the table 28.

Also in this example, the table 28 uses a read-only memory, and the change mode of the light quantity is typically 4 to 8.
It is the same as in the case of FIG. 2 that the optimum display luminance information is actually measured and stored corresponding to each of these 4 to 8 light intensity change modes.

5 and 6, changes in the ambient light amount A, B,
Actual control examples of display brightness for C and D A ′, B ′,
C'and D'are shown respectively. FIG. 5 shows examples of dark adaptation control in the case where the amount of ambient light suddenly changes from bright to dark, for two examples A and B. Actually, for each of the ambient light amount change examples A and B, the display luminance is controlled to change in a time-wise manner as A ′ and B ′ in a manner similar to the human dark adaptation characteristic.

FIG. 6 shows examples of bright adaptation control when the amount of ambient light suddenly changes from dark to bright, for two examples C and D. Actually, for each of the ambient light intensity change examples C and D,
In accordance with human light adaptation characteristics, the display brightness is controlled to change like C'and D'in a stepwise manner with respect to time.

[0035]

As described above, according to the present invention, even when the light quantity in the passenger compartment changes, driving is not hindered and good visibility can be obtained. Therefore, when entering a tunnel under the scorching sun or from a high illumination area at night. Even when the road is moved to a dark road in the mountain area, the display brightness can be smoothly changed according to the pupil adjustment time. Therefore, it is possible to prevent temporary dazzling and prevent glare due to excessive light.

[Brief description of drawings]

FIG. 1 is a schematic functional block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of a CPU 3 in the block of FIG.

FIG. 3 is a diagram showing an example of a temporal change of the pupillary opening amount with respect to a certain temporal change of the ambient light amount, and a diagram showing an example of temporal control of display brightness with respect to the temporal change of the pupillary opening amount.

FIG. 4 is a flowchart showing another operation of the CPU 3 in the block diagram of FIG.

FIG. 5 is a diagram showing an actual example of dark adaptation control when the amount of ambient light changes from bright to dark.

FIG. 6 is a diagram showing an actual example of bright adaptation control when the amount of ambient light changes from dark to bright.

FIG. 7 is a block diagram showing an example of display control of a conventional vehicle interior display device.

[Explanation of symbols]

 1 display device 2 display drive circuit 3 CPU 4 optical sensor 5 amplifier 6 A / D converter

Claims (3)

[Claims] 1. A display means for displaying characters and figures, a light detection means for detecting a light quantity around the display means and generating a detection signal corresponding to the light quantity, and a light detection means for responding to a change in the detection signal. A light amount variation time function calculating means for calculating a time function of the variation of the light amount, and the display set by preliminarily estimating a time function of the variation of the pupil opening amount of the viewer corresponding to the calculated light amount variation time function. A display device comprising: a display brightness determining unit that determines a display brightness of the unit; and a display control unit that controls a display brightness of the display unit according to the determined display brightness. 2. The display brightness determining means stores the display brightness information of the display means, which is determined by preliminarily estimating a time function of a change in the pupillary aperture of a viewer corresponding to the light amount variation time function. The display device according to claim 1, wherein the display device is a table. 3. A light quantity variation time function calculating means, converting means for converting the detection signal into a digital signal, and time variation information indicating a time variation state of the digital signal in response to a change in the detection signal. The display luminance determining means includes a reference means for referring to the storage table according to the temporal variation information obtained by the temporal variation information generating means, The display device according to claim 2, wherein reference information from a table is used as the display brightness information.