JPH0659889U - In-vehicle display brightness adjustment mechanism - Google Patents

Abstract

(57) [Abstract] [Purpose] To automatically adjust the brightness of an in-vehicle display in accordance with the ambient brightness to eliminate the excessive glare and insufficient brightness of the display screen. [Structure] Light receiving elements 2a to 2c arranged toward both side surfaces and a rear side of a vehicle body 11 detect ambient brightness, and a maximum level among them is discriminated by a discrimination circuit 3. The time constant circuit 5 buffers a sudden change in the discrimination output.
The brightness adjustment circuit 6 appropriately adjusts the brightness of the display in which the excessive brightness, the insufficient brightness, and the abrupt change in the brightness corresponding to the ambient brightness are eliminated, and the visibility is improved and the safety is improved.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a brightness adjusting mechanism for an on-vehicle display, which is preferably implemented in, for example, an in-vehicle display device or an in-vehicle television.

[0002]

[Prior art]

 Recently, an increasing number of vehicles are equipped with vehicle-mounted display devices such as navigation systems and television receivers. A display means such as a so-called cathode ray tube (CRT) or a liquid crystal display panel (LCD) with a backlight is used for these display devices, and the brightness thereof is set to be high enough to be visually recognized even during daytime running under sunlight. ing.

[0003]

[Problems to be solved by the device]

 Since the brightness of the conventional in-vehicle display device as described above is set to high brightness, it is rather dazzling when placed in a tunnel while driving, or when the surroundings are dark such as at night. Not only does it hinder the visibility of other currently used instruments, but it also causes problems such as tired eyes for safe driving. For this reason, depending on the type of vehicle, the brightness of the display can be switched between two levels of light and dark depending on day and night, and there is also a manual brightness adjustment means. However, it is time-consuming to adjust the brightness according to the brightness of the surroundings while driving, and it is dangerous because it requires the driver's attention. In addition, automatic adjustment is not enough at the second stage, and there is a problem that there is a large drop due to an instantaneous change in brightness, which in turn causes eyestrain and affects safe driving.

Therefore, an object of the present invention is to appropriately change the brightness of an in-vehicle display according to the ambient brightness, adjust the brightness to an optimum level to improve visibility, and to contribute to safe operation. It is to provide a brightness adjustment mechanism for a display.

[0005]

[Means for Solving the Problems]

 The present invention relates to a brightness adjusting mechanism for a vehicle-mounted display provided in a vehicle compartment, wherein an illuminance detecting means for detecting ambient brightness in a plurality of directions and a maximum level of outputs from the plurality of illuminance detecting means are controlled. A brightness adjusting mechanism for an on-vehicle display, comprising: a level discriminating means which outputs separately and a luminance adjusting means which adjusts the luminance of the display in response to an output of the level discriminating means.

[0006]

[Action]

 The brightness adjusting mechanism of the in-vehicle display according to the present invention detects the ambient brightness in a plurality of directions by the plurality of illuminance detecting means, and the maximum level among the brightness detected by the level discriminating means. The brightness adjusting means always keeps the brightness of the on-vehicle display at an optimum level in accordance with the output of the level distinguishing means. As a result, the brightness of the display will not be insufficient in bright places, and on the contrary, it will not be too dazzling in dark places, good visibility will be maintained, and there will be no obstruction to the visibility of instruments arranged in close proximity. Safety is improved.

[0007]

【Example】

 FIG. 1 is a block diagram showing an electrical configuration of a brightness adjusting mechanism of an in-vehicle display according to an embodiment of the present invention. The brightness adjustment mechanism 1 for an on-vehicle display includes light receiving elements 2a, 2b, 2c which are illuminance detecting means for detecting ambient brightness (hereinafter, also referred to as illuminance) in a plurality of directions, and the plurality of light receiving elements. A level discriminating circuit 3 which is a discriminating means for discriminating and outputting the highest level from the detection outputs of 2a, 2b, 2c and a luminance adjusting means for adjusting the luminance of an in-vehicle display (hereinafter referred to as display) 7 are formed. The amplifier circuit 4, the time constant circuit 5, and the brightness adjusting circuit 6 are formed by respective blocks.

The light receiving elements 2a to 2c are semiconductor elements realized by, for example, PIN diodes, and outputs linearly corresponding to the amount of received light, that is, the illuminance level. The level discriminating circuit is realized by, for example, a diode OR circuit corresponding to each of the light receiving elements 2a to 2c, and discriminates and outputs the maximum level among the detection levels of the light receiving elements 2a to 2c. The output of the level discrimination circuit 3 is amplified to a predetermined level by the amplification circuit 4 at the next stage and input to the time constant circuit 5. The time constant circuit 5 is realized by, for example, an integrating circuit including a resistor and a capacitor, and absorbs a momentary change in input to buffer a sudden change in luminance of the display 7. The output of the time constant circuit 6 is input to the brightness adjusting circuit 6 to adjust the brightness of the cathode ray tube of the display 7 and the backlight of the liquid crystal screen, and always maintain the optimum brightness level in response to changes in ambient brightness. is there.

As shown in FIG. 2, the plurality of light receiving elements 2a to 2c are arranged in the surroundings of the vehicle body of the automobile 11, for example, the first and second light receiving elements 2a and 2b are the left side surface and the right side surface of the vehicle body. The third light receiving element 2c is mounted near the id mirror and near the rear plate by using appropriate means. However, the mounting position is not limited to this, and the number of light receiving elements is not limited to three, but avoid changing the brightness due to the light of the oncoming vehicle during night driving. Therefore, it is possible not to install it in front of the vehicle body. In this way, the first and second light receiving elements 2a and 2b detect the lights P1 and P2 from the diagonal rear of the vehicle body, and the third light receiving element 2c detects the light P3 from the rear of the vehicle body. The light detects the illuminance around the vehicle body and its changes. The detection outputs of the light receiving elements 2a, 2b, 2c are input to the level discrimination circuit 3.

The level discrimination circuit 3 is realized by, for example, a diode OR circuit in which a plurality of diodes are made to correspond to the light receiving elements 2a to 2c, and the maximum level of the detection output is taken out and the amplification circuit 4 of the next stage is obtained. After being level-amplified by, the illuminance detection signal S is input to the time constant circuit 5. As shown in the graph of FIG. 3, the illuminance detection signal S linearly increases in proportion to the illuminance A, but the amplifier circuit 4 has a limiter function so as to maintain a constant level Smax at a predetermined level As or higher. Has been. Therefore, the change in the brightness B of the display 7 is suppressed within a certain level range, and the change is made gentle by the time constant circuit 5 in the next stage so as not to hinder the operation. The time constant circuit 5 is realized by, for example, an integrating circuit composed of a resistor and a capacitor, and as shown in the graph of FIG. 4, due to the charge / discharge characteristics of the capacitor determined by the time constant CR of the resistance value R and the capacitance value C. The instantaneous change in the illuminance detection signal Smax is absorbed and absorbed.

FIG. 4 is a graph showing the operation of this embodiment. In the graph, the horizontal axis represents time, and the vertical axis represents the brightness (illuminance) A of the surrounding area and the level of the brightness B of the display 7. The change of the illuminance A shown by the solid line and the change of the brightness B shown by the broken line. Is shown. Although the levels of the illuminance A and the brightness B are different from each other, they are overlaid for the sake of convenience in order to show the relative relationship. In the normal traveling state until time t1, the brightness B of the display is maintained at the level L2. At time t1, for example, a tunnel is entered, and at this time, the illuminance A sharply drops from the level L2 to the level L1, but the brightness B is changed by the time constant circuit 5 despite the stepwise change of the illuminance A. The change becomes gradual and settles to a constant level L1 after a time determined by the time constant. Also, during the period from time t3 to t4, it is assumed that there is a so-called temporary change ΔL in brightness such as when the building is shaded, but the brightness B does not change instantaneously at this time as well. . Therefore, the flicker of the display 7 is prevented even when the illuminance changes frequently, such as when passing through a bridge or a protective canopy, and the visibility of operating instruments is significantly improved. Also, when the illuminance changes drastically due to the light of the vehicle behind when driving at night, the brightness B of the display changes gently and the level is kept within a certain range, which is a burden on the driver's eyes. This will alleviate problems and prevent problems such as hindering driving.

[0012]

[Effect of device]

 As described above, according to the present invention, the ambient brightness is detected in a plurality of directions by the plurality of light receiving elements, the maximum brightness level among them is discriminated by the level discriminating circuit, and the abruptness of the brightness level is further increased. These changes are buffered via the time constant circuit and changed to a gentle level change to be input to the brightness adjustment circuit, so the brightness of the in-vehicle display is always kept at the optimum level according to the ambient brightness. Therefore, the problems such as insufficient brightness of the display in bright places and excessive glare in dark places are resolved, and good visibility of the display is maintained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a brightness adjusting mechanism of a vehicle-mounted display according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement of light receiving elements of the present embodiment.

FIG. 3 is a graph showing the relationship between the brightness of the display of the present embodiment and the ambient brightness.

FIG. 4 is a graph showing the operation of this embodiment.

[Explanation of symbols]

 1 In-vehicle display brightness adjusting mechanism 2a to 2c Light receiving element 3 Level discrimination circuit 5 Time constant circuit 6 Brightness adjusting circuit 7 In-vehicle display 11 Vehicle body P1, P2 Light from diagonally rearward of vehicle body P3 Light from rearward of vehicle body

Claims (1)

[Scope of utility model registration request] 1. A brightness adjusting mechanism for a vehicle-mounted display provided in a vehicle interior, comprising: an illuminance detecting means for detecting ambient brightness in a plurality of directions; and a maximum level of outputs from the plurality of illuminance detecting means. A brightness adjusting mechanism for an on-vehicle display, comprising: a level discriminating means for discriminating and outputting; and a luminance adjusting means for adjusting the luminance of the display in response to an output of the level discriminating means.