JP3288882B2 - Visometer test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test device for a visibility meter that photographs a target placed near a road, processes the image, and measures a visibility value.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a configuration of a conventional visibility meter test apparatus. In FIG. 5, reference numeral 2 denotes a target formed by combining a white portion 2a and a black portion 2b of a triangle to form a diamond. Reference numeral 3 denotes an image of the target 2 taken by a television camera (not shown) provided in advance, and the image is processed to obtain a difference in luminance between the white portion 2a and the black portion 2b. Is a visibility meter that measures The visibility meter 3 and the target 2 constitute a visibility measurement device.

In actual use of the visibility meter 3, the target 2 is placed near the road, and the visibility meter 3 is placed at a predetermined distance from the target 2. For example, if snow exists between the target 2 and the visibility meter 3 due to snowfall,
The visibility of the target 2 as viewed from the visibility meter 3 deteriorates, making it difficult to distinguish between the white portion 2a and the black portion 2b of the target 2, and the visibility value becomes shorter (smaller). That is, the visibility meter 3
Is such that the above-mentioned distinction can be made quantitatively, and the brightness difference between the white portion 2a and the black portion 2b of the target 2 can be calculated. For example, when the amount of snowfall increases, the visibility meter 3
The brightness difference between the white portion 2a and the black portion 2b detected by the above becomes small, which means that the distance (the visibility value) by which the white portion 2a and the black portion 2b can be distinguished becomes short. Because it is dangerous, information such as road speed regulation and traffic stop is output.

[0004] A frosted glass 1 is used for performing a characteristic test on the visibility meter 3 after manufacturing and the like, and is disposed between the target 2 and the visibility meter 3 to simulate a change in visibility value due to snowfall. It is.

Next, the method and operation of the characteristic test of the visibility meter 3 will be described. First, in a state in which the ground glass 1 having a predetermined transmittance is not interposed between the target 2 and the visibility meter 3, the visibility meter 3 photographs the target 2 with a television camera (not shown), processes the image, and processes the image of the target 2. Each brightness of the portion 2a and the black portion 2b is converted into a numerical value, and a visibility value is measured based on the brightness difference. Next, in a state where the ground glass 1 is interposed between the target 2 and the visibility meter 3, the visibility meter 3 photographs the target 2 through the ground glass 1 with a television camera, processes the image and processes the image with the white portion 2a of the target 2. Each luminance of the black portion 2b is digitized, and the visibility value is measured based on the luminance difference. The difference in brightness between the white portion 2a and the black portion 2b of the target 2 changes between the state in which the ground glass 1 is not interposed and the state in which the ground glass 1 having a predetermined transmittance is interposed, and the visibility value also changes. The static characteristics of the visibility meter 3 can be evaluated by comparing the light transmittance of No. 1 with the visibility value.
Such a test is performed while changing various types of frosted glass having different transmittances, and data on visibility values is obtained.

[0006]

The conventional visibility tester for a visibility meter is constructed as described above, and compares the light transmittance of the ground glass with the visibility value while replacing the ground glass with one having a different light transmittance. In addition, the static characteristics of the visibility meter 3 can be evaluated. However, the conventional visibility tester is effective for static characteristics evaluation.However, in simulations before shipping the visibility meter, the frosted glass used in place of snowfall has a constant light transmittance. If the field of view changes suddenly due to a sudden change, it cannot be simulated, and dynamic characteristics cannot be evaluated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a test device for a visibility meter capable of performing dynamic characteristics evaluation as well as static characteristics evaluation of the visibility meter. .

[0008]

According to a first aspect of the present invention, there is provided a liquid crystal device 11 disposed between a target 2 and a visibility meter 3 and capable of changing light transmittance, and a light transmittance of the liquid crystal device 11 is measured by a visibility meter.
And a transmittance control device 41 for performing control based on a synchronization signal obtained from the video signal from the control unit 3.

According to a second invention, in the configuration of the first invention, the transmittance of the liquid crystal device 11 is controlled by the transmittance control device 41 so that the image measured by the visibility meter 3 can simulate snowfall or the like. It is characterized by the following.

A third aspect of the present invention is characterized in that a brightness control device 42 or 43 for controlling the brightness of the light source (LED 21) in the white portion of the target 2 is provided.

According to a fourth aspect of the present invention, in the configuration of the third aspect, a current limiting resistance element R connected to the light source (LED 21) of the target 2 for changing the luminance of the light source is provided.
1 and R2 are switched by the brightness control device 42.

According to a fifth aspect of the present invention, in the configuration of the third aspect, the pulse width of a current flowing through the light source (LED 21) of the target 2 is changed to change the luminance of the light source (LED 21).
3 is controlled.

According to a sixth aspect of the present invention, in the configuration of the fourth or fifth aspect, the luminance of the light source (LED 21) of the target 2 and the snowfall or the like are changed so as to simulate.

[0014]

According to the first aspect of the invention, the light transmittance of the liquid crystal device is converted into a video signal from the visibility meter by the transmittance control device.
The control is performed based on the generated synchronization signal . Therefore, the brightness of the light reaching the visibility meter 3 from the target 2 changes.

In the second invention, the light transmittance of the liquid crystal device 11 is controlled by the transmittance control device 41 so as to simulate snowfall or the like. Therefore, the brightness of the light reaching the visibility meter 3 from the target 2 changes as in a simulation of snowfall or the like.

In the third aspect, the luminance of the light source in the white portion of the target 2 is controlled by the luminance control device 42 or 43. Therefore, the brightness of the light reaching the visibility meter 3 from the target 2 changes.

In the fourth aspect, the resistance elements R1 and R2 for current limiting are switched by the luminance control device 42, and the luminance of the light source of the target 2 changes. Therefore, the brightness of the light reaching the visibility meter 3 from the target 2 changes.

In the fifth aspect, the pulse width of the current flowing through the light source of the target 2 is controlled by the luminance control device 43, and the luminance of the light source of the target 2 changes. Therefore, the brightness of the light reaching the visibility meter 3 from the target 2 changes.

In the sixth aspect, the luminance of the light source of the target 2 changes so as to simulate snowfall or the like.

[0020]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a test device for a visibility meter according to Embodiment 1 of the present invention. 1, components corresponding to those shown in FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, reference numeral 11 denotes a liquid crystal device arranged between the target 2 and the visibility meter 3 and capable of changing the light transmittance. Reference numeral 41 denotes a transmittance control device that controls the transmittance of light of the liquid crystal device 11, a synchronization signal generation circuit 41a that generates a synchronization signal based on a video signal from the visibility meter 3, and
A voltage output circuit 41b for outputting a voltage signal for driving the liquid crystal device 11 in accordance with the synchronization signal.

Next, the method and operation of the characteristic test of the visibility meter will be described. In order to perform a dynamic characteristic test of the visibility meter 3, the transmittance control device 41 inputs a video signal from a television camera (not shown) of the visibility meter 3 to the synchronization signal generation circuit 41a, and scans one screen (for example, about 33 msec). A synchronization signal is generated by a synchronization signal generation circuit 41a, and a voltage signal is sent to the liquid crystal device 11 at each timing.
Output from Thus, the liquid crystal device 11 instantaneously (for example, about 1 msec) rotates the molecules on the liquid crystal surface in response to the voltage signal, and changes the light transmittance. Therefore, the white portion 2a and the black portion 2 of the target 2 captured by the visibility meter 3
The difference in luminance of b changes, and a corresponding visibility value can be obtained every one screen scanning time (for example, about 33 msec). That is, when the transmittance of the liquid crystal device 11 is controlled by the transmittance control device 41 so that the image measured by the visibility meter 3 can simulate snowfall or the like, the visibility meter 3 obtains a visibility value that can also perform dynamic characteristic evaluation. be able to. In addition, the static characteristic test of the visibility meter 3
It goes without saying that if D21 is normally lit, this can be done.

Embodiment 2 FIG. FIG. 2 is a block diagram showing a configuration of a visibility meter test apparatus according to Embodiment 2 of the present invention. FIG.
In FIG. 5, components corresponding to those shown in FIG. 5 are given the same reference numerals, and descriptions thereof will be omitted. In FIG. 2, 4
Reference numeral 2 designates a white portion 2a of the target 2 as a plurality of light sources, for example, L
A current limiting resistor R1, connected to the LED 21 for changing the luminance of the LED, comprises an ED 21.
This is a brightness control device for switching R2. S1 is a resistance element R
1 is a switch connected in parallel to the switch, and S2 is a switch connected in parallel to the resistance element R2.

Next, the method and operation of the characteristic test of the visibility meter will be described. In order to perform a dynamic characteristic test of the visibility meter 3, the brightness control device 42 switches the switches S1 and S2 to the visibility meter 3.
Are turned on / off in synchronization with the video signal from the CPU, and the resistance elements R1 and R2 are switched. As a result, the brightness of the white portion 2a of the target 2 can be changed, the difference between the brightness of the white portion 2a and the brightness of the black portion 2b substantially changes, and the visibility meter 3 can perform a dynamic characteristic evaluation including a snowfall state. Can be obtained.

In the first embodiment, the white portion 2a of the target 2 is changed by changing the light transmittance of the liquid crystal device 11.
The case where the visibility difference of the visibility meter 3 is changed by changing the luminance difference between the black portion 2b and the black portion 2b has been described.
The LED 21 of the white portion 2a of the target 22 as shown in FIG.
Is changed by switching the current limiting resistance elements R1 and R2 connected in series to the LED 21, so that the visibility tester can be configured at a lower price than in the first embodiment.

Embodiment 3 FIG. FIG. 3 is a block diagram showing a configuration of a visibility meter test apparatus according to Embodiment 3 of the present invention. 3, components corresponding to those shown in FIG. 2 are given the same reference numerals, and descriptions thereof will be omitted. In FIG.
Reference numeral 43 denotes a brightness control device that controls the pulse width of a current flowing through the LED 21 in order to change the brightness of the LED 21 of the target 2, and a pulse width control circuit that controls the pulse width of a pulse current synchronized with a video signal from the visibility meter 3. 43a
And a drive circuit for driving the LED 21 of the white portion 2a of the target 2 with the pulse current output from the pulse width control circuit 43a.

Next, the method and operation of the characteristic test of the visibility meter will be described. In order to perform a dynamic characteristic test of the visibility meter 3, the brightness control device 43 changes the pulse width of the pulse current by the pulse width control circuit 43a to change the brightness of the LED 21 of the target 2. For example, as shown in FIG. 4, when the cycle of the pulse current is T, the on-time is T1, and the off-time is T2, the pulse width control circuit 43a determines the on-time T
The luminance of the LED 21 is changed by changing the ratio (duty ratio) between 1 and the off time T2. And
The pulse current whose duty ratio has been changed in this manner is driven by the LE 43 of the white portion 2a of the target 2 via the drive circuit 43b.
D21 is applied to drive LED21. As a result, the difference in luminance between the white portion 2a and the black portion 2b of the target 2 changes, and the visibility meter 3 can obtain a visibility value capable of performing dynamic characteristic evaluation including a snowfall state.

In the second embodiment, the brightness of the LED 21 of the white portion 2a of the target 2 is changed by switching the resistance elements R1 and R2 for limiting the current connected in series to the LED 21, but the third embodiment is different from the third embodiment. Since the brightness of the LED 21 is changed by switching the pulse width of the current flowing through the LED 21 as shown in FIG.
The level of the change in the brightness of the LED 21 can be increased without limitation.

[0028]

As described above, according to the first aspect of the invention, a liquid crystal device which is arranged between a target and a visibility meter and whose light transmittance can be changed, and the light transmittance of the liquid crystal device is measured by the visibility meter. Bi
It is equipped with a transmittance control device that controls based on a synchronization signal obtained from a video signal . Therefore, by changing the light transmittance of the liquid crystal device, it is possible to evaluate not only the static characteristics of the visibility meter but also the white portion of the target. And the brightness of the black part
Obtain the visibility value corresponding to the change of the degree every one screen scanning time
Rukoto can, dynamic characterization also can Ru can <br/> performed. Therefore, the effect that the test range of the visibility meter is expanded and the performance of the visibility meter can be sufficiently tested is obtained.

According to the second invention, in the configuration of the first invention, the transmittance of the liquid crystal device is controlled by the transmittance control device so that the image measured by the visibility meter can simulate snowfall or the like. The configuration makes it possible to simulate snowfall and the like by changing the light transmittance of the liquid crystal device, thereby enabling not only static characteristic evaluation but also dynamic characteristic evaluation of the visibility meter. The effect is obtained that the range is expanded and the performance of the visibility meter can be sufficiently tested.

According to the third aspect of the invention, the white portion of the target is constituted by the light source and the luminance control device for controlling the luminance of the light source is provided. In addition to the static characteristic evaluation, the dynamic characteristic evaluation can be performed, so that the test range of the visibility meter can be expanded, and the effect that the performance of the visibility meter can be sufficiently tested can be obtained.

According to a fourth aspect of the present invention, in the configuration of the third aspect of the invention, in order to change the brightness of the light source of the target, the current limiting resistance element connected to the light source is switched by the brightness control device. Therefore, by switching the resistance element, the brightness of the light source of the target can be changed, whereby not only the static characteristic evaluation of the visibility meter but also the dynamic characteristic evaluation can be performed. As a result, the effect that the performance of the visibility meter can be sufficiently tested can be obtained.

According to the fifth aspect, in the configuration of the third aspect, the pulse width of the current flowing through the light source for changing the luminance of the target light source is controlled by the luminance control device. By changing the width, the brightness of the light source of the target can be changed, which allows not only static characterization of the visibility meter but also dynamic characterization, thus expanding the test range of the visibility meter, The effect is obtained that the performance of the visibility meter can be sufficiently tested.

According to the sixth invention, the fourth invention or the fifth invention
In the configuration of the invention of the present invention, the brightness of the light source of the target is changed so as to simulate snowfall and the like, so that the snowfall and the like can be simulated by changing the brightness of the light source of the target. In addition to accurate characteristic evaluation, dynamic characteristic evaluation can be performed, so that the test range of the visibility meter can be expanded, and the effect that the performance of the visibility meter can be sufficiently tested can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a visibility meter test apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a visibility meter test apparatus according to Embodiment 2 of the present invention.

FIG. 3 is a block diagram showing a configuration of a visibility meter test apparatus according to Embodiment 3 of the present invention.

FIG. 4 is a waveform chart for explaining a pulse current in a third embodiment.

FIG. 5 is a block diagram showing a configuration of a conventional visibility meter test apparatus.

[Explanation of symbols]

1 ground glass, 2 target, 2a white part, 2b
Black part, 3 visibility meter, 21 LED (light source), 41
Transmittance control device, 42, 43 Brightness control device, 41a
Synchronization signal generation circuit, 41b voltage output circuit, 43a pulse width control circuit, 43b drive circuit, R1, R2 resistance element, S1, S2 switch.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01M 11/00-11/08 G01W 1/00-1/18

Claims (6)

(57) [Claims] An image of a target having a white part and a black part adjacent to each other is photographed, and the image is processed to determine a difference in luminance between the white part and the black part, and a visibility value is measured based on the luminance difference. A liquid crystal device disposed between the target and the visibility meter, the transmittance of which is variable, and a light transmittance of the liquid crystal device measured by a video signal from the visibility meter.
And a transmittance control device for controlling based on a synchronizing signal obtained by an e-signal . 2. The test of a visibility meter according to claim 1, wherein the transmittance of the liquid crystal device is controlled by a transmittance control device so that the image measured by the visibility meter can simulate snowfall or the like. apparatus. 3. A target having a white portion and a black portion adjacent to each other is photographed, and the image is processed to determine a difference in luminance between the white portion and the black portion, and a visibility value is measured based on the luminance difference. And a brightness control device for controlling the brightness of the light source, wherein the white portion of the target is constituted by a light source. 4. A test device for a visibility meter according to claim 3, wherein, in order to change the brightness of the light source of the target, a resistance element for limiting the current connected to the light source is switched by a brightness control device. . 5. The apparatus according to claim 3, wherein a pulse width of a current flowing through the light source is controlled by a luminance control device in order to change the luminance of the light source of the target. 6. A test device for a visibility meter according to claim 4, wherein the luminance of the light source of the target is changed so as to simulate snowfall or the like.