JPS6112209B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for measuring the illuminance of road lighting by mounting a measuring device on a vehicle and performing the illuminance measurement while the vehicle is running. When there are other vehicles with their taillights on, the purpose of this method is to remove illuminance measurements that include errors of a certain value or more due to the lights of these other vehicles.

When measuring the horizontal illuminance on the road surface using a vehicle for road lighting, the illuminance meter receiver is usually placed 150 mm above the road surface, taking into consideration the two conflicting aspects of vehicle driving safety and ensuring illuminance measurement accuracy. It is set to height. When setting the illumination meter light receiver at this height, if it is simply attached to a part of the vehicle, a problem arises in that a portion of the light entering the light receiver is blocked by the vehicle body. For this reason, in conventional illuminance measurement, measures shown in FIGS. 1 and 2 have been taken. In Figure 1, in order to increase the distance between vehicle A and receiver B, illuminance meter receiver B is placed behind vehicle A.
This method involves towing a trailer C carrying a truck.
Figure 2 shows how the illuminance at an arbitrary measurement point is divided into two parts.
Illuminance meter receiver B is installed at the front and rear of vehicle A, respectively.
Attach B' and connect the output of receiver B at the front of the vehicle.
This method calculates the illuminance at the measurement point by adding the output from the light receiver B' at the rear of the vehicle measured at the same point after a certain period of time (0.2 to 0.5 seconds) has elapsed.
For example, when measuring illuminance on a road before it is put into service, if there are no vehicles other than those used for measurement on the road on which illuminance is to be measured, use the method shown in Figure 1 or Figure 2 to measure the illuminance on a horizontal surface on the road surface. Illuminance can be measured.

However, when measuring illuminance on a road that is in use, there are other vehicles around the vehicle being measured, so the lights of these vehicles (headlights, taillights, etc.) may cause measurement errors in the horizontal illuminance. . As an example, when the measurement method shown in FIG. 1 is used, the influence of the headlights of a following vehicle on the horizontal illuminance will be considered. Figure 3 shows ordinary road lighting (the light source is a high-pressure mercury lamp).
This figure shows the distribution of horizontal illuminance and vertical illuminance between two lamps (35 m) using 400 W). It can be seen that the horizontal illuminance due to the road illumination shown in FIG. 3 has a maximum value of 41x, a minimum value of 16x, and an average value of 28x.

Next, FIG. 4 shows the relationship between the horizontal illuminance of the vehicle headlight and the distance on the maximum beam axis from the headlight. As is clear from FIG. 4, the horizontal illuminance in front of the headlights is approximately 8x at maximum. Therefore, if the maximum value of the horizontal illuminance is irradiated by the headlight while measuring the minimum value of the horizontal illuminance due to road lighting, the measurement error will be the largest, reaching about 50%.

The present invention eliminates the above-mentioned problems and makes it possible to measure horizontal illuminance on a road surface due to road illumination within a predetermined measurement error range. Hereinafter, the details of the present invention will be explained with reference to Examples.

In the measurement of normal road lighting, the measurement error of horizontal illuminance is specified to be within 5%. In road lighting with the illuminance distribution shown in Figure 3, in order to keep the measurement error of horizontal illuminance within 5%, the horizontal illuminance due to headlights should be at least within 5% of the average horizontal illuminance due to road lighting. There is a need. In this case, the permissible range of horizontal illuminance due to headlights is 1.4x or less. However, since the measurement error of horizontal surface illuminance includes factors other than the influence of headlights, the allowable range of horizontal surface illuminance due to headlights is set to 0.5x or less here.

Next, FIG. 5 shows the vertical illuminance distribution in front of the headlights. From FIG. 5, it can be seen that the vertical illuminance distribution in front of the headlights is a maximum of 130x in the case of a passing beam and 20x in the case of a running beam.

On the other hand, as shown in FIG. 3, the vertical illuminance due to road lighting is lower than the horizontal illuminance in both the maximum and minimum values, so the measurement error due to headlights is larger in the vertical illuminance than in the horizontal illuminance. From Figures 4 and 5, for example, the horizontal illuminance due to headlights is
It can be seen that at 0.5x, the vertical illumination is 26x for the passing beam and 18x for the running beam.

Now, if we take the ratio of the maximum value to the minimum value for horizontal surface illuminance and vertical surface illuminance, respectively, the maximum value/minimum value of horizontal surface illuminance due to road lighting is 2.6 without headlights, whereas the horizontal surface illuminance due to headlights is 2.6. Illuminance 0.5x
is added, it decreases to 2.5. Also, the maximum/minimum value of vertical illuminance due to road lighting is 7.7 without headlights, but when vertical illuminance from headlights is added, it is 1.7 (passing beam)
Or reduced to 2.0 (traveling beam). that's all,
FIG. 6 shows the relationship between the maximum/minimum values of the horizontal illuminance and vertical illuminance described above and the measurement error. From Figure 6, the maximum/minimum values of the horizontal illuminance hardly change even if the measurement error of the horizontal illuminance increases, whereas the maximum/minimum values of the vertical illuminance change, especially with a measurement error of 0 to 3%. You can see that it changes significantly. In other words, as is clear from Fig. 6, in order to eliminate the influence of the irradiation direction of the headlights (traveling beam or passing beam), the permissible measurement error for horizontal illuminance should be reduced by 2% to the maximum value of vertical illuminance/
The minimum value must be set to 3.

The present invention utilizes the relationship between the measurement error of the horizontal illuminance and the maximum/minimum value of the vertical illuminance.

The block diagram of the illuminance measuring device according to the present invention is shown in Fig. 7.
As shown in the figure. This measurement device consists of a horizontal illuminance measurement circuit, a vertical illuminance measurement circuit, and a lamp position detection circuit. The horizontal illuminance is converted into an electrical signal by a light receiver 10 and then sent to an analog switch 12 via an amplifier 11. The vertical illuminance is determined by the receiver 13.
After being converted into an electrical signal, the maximum value and minimum value of the vertical illuminance are detected by the maximum value detection circuit 15 and minimum value detection circuit 16 through the amplifier 14, respectively. Maximum value detection circuit 15 and minimum value detection circuit 1
The output signal of 6 is divided by a division circuit 17, and the ratio of the maximum value to the maximum value of the vertical illuminance is obtained as the output of the division circuit 17. The comparator 18 is operated by the output of the division circuit 17 and
When the output is above a certain voltage, that is, when the maximum illuminance/minimum illuminance is above a certain value, it becomes high level and turns on the analog switch 12.

Conversely, when the output of the divider circuit 17 is below a certain voltage, the output of the comparator 18 becomes low level, turning off the analog switch 12. Therefore, in this case, the horizontal illuminance is set by analog switch 1.
2, the output of the analog switch 12 becomes zero.

Further, the maximum value detection circuit 15 and the minimum value detection circuit 16 are cleared by a pulse generated by a position detection circuit 19 directly below the lamp and a waveform shaping circuit 20 when the horizontal illuminance measuring receiver 10 passes directly below the lamp. , calculate the maximum value/minimum value of vertical illuminance for each lamp interval.

According to the configuration shown in FIG. 7, depending on the measurement error of the illuminance between two lamps, it is determined whether to adopt the horizontal illuminance between the next two lamps. Normally, the distance between vehicles is 30,000
Since there is no sudden change between 40m and 40m, there is no problem with the configuration shown in Figure 7. If the time delay in detecting measurement errors in the configuration shown in FIG. 7 poses a measurement problem, this can be solved by using the delay circuits shown in FIGS. 8 and 9.

Figure 8 shows a BBD (bucket brigade device) between the horizontal illuminance amplifier 11 and the analog switch 12.
By installing an analog delay circuit 21 such as 21 and operating it with a pulse signal proportional to the running speed of the measuring vehicle, the horizontal illuminance between the lamps where a measurement error is detected from the vertical illuminance can be turned on and off using an analog switch. can do.

In FIG. 9, the analog delay circuit 21 in FIG. 8 is replaced with a digital delay circuit, and an A/D converter 30,
This is an example configured with a shift register 31 and a D/A converter 32. As in FIG. 8, the shift register 31 is driven by a pulse signal proportional to the traveling speed of the measuring vehicle.

In addition, if the influence of the headlights of a vehicle approaching the measurement vehicle across the lane on a road with two-way traffic becomes a problem, this can be solved by providing two vertical illuminance measurement circuits.

As described above, the present invention calculates and measures the measurement error of horizontal illuminance from the maximum/minimum values of vertical illuminance. Therefore, measurement errors in horizontal surface illuminance can be detected with high sensitivity using vertical surface illuminance. As a result, the horizontal illuminance that caused a measurement error of 5% or more due to the headlights is removed, and the horizontal illuminance can be measured with a predetermined measurement accuracy. Since the influence of headlights on horizontal illuminance is detected by the relative value (maximum value/minimum value) of vertical illuminance, it is not affected by the absolute level of illuminance on the road surface due to road illumination.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an illuminance measuring device for towing a trailer, Fig. 2 is an explanatory diagram of an illuminance measuring device using a receiver division method, Fig. 3 is a characteristic diagram of horizontal illuminance and vertical illuminance in road lighting, and Fig. 4 Figure 5 is a horizontal illuminance distribution characteristic diagram in front of the headlights, Figure 5 is a vertical illuminance distribution characteristic diagram in front of the headlights, Figure 6 is a diagram showing the measurement error and the ratio of the maximum value to the minimum value of illuminance, and Figure 7 is a diagram showing the ratio of the maximum value to the minimum value of illuminance. The figure is a block diagram of an illuminance measuring device according to an embodiment of the present invention.
FIG. 8 is a diagram of the analog delay circuit, and FIG. 9 is a diagram of the digital delay circuit. DESCRIPTION OF SYMBOLS 10... Receiver for detecting horizontal illuminance, 11... Amplifier, 12... Analog switch, 13... Receiver for detecting vertical illuminance, 14... Amplifier, 15... Maximum value detection circuit, 16... Minimum value detection circuit, 17... division circuit, 18... comparator, 19... position detection circuit directly below the lamp, 20... waveform shaping circuit.

Claims (1)

[Scope of Claims] 1. An illuminance measuring device mounted on a vehicle and carried out while the vehicle is running, comprising: a light receiver for measuring horizontal illuminance on a road surface; a light receiver for measuring vertical illuminance in the axial direction of the road; A maximum value detection circuit that detects the maximum value of vertical illuminance, a minimum value detection circuit that detects the minimum value of vertical illuminance, a divider that calculates the ratio of the maximum value to the minimum value of vertical illuminance, and a divider. a comparator that operates when the output is above a certain voltage;
Turns on when the comparator output is high level,
An analog switch that turns off when the level is low,
It is composed of a position detection circuit directly below the lamp and a waveform shaping circuit that detects the position directly below the lamp and clears the maximum and minimum values of the vertical illuminance each time the horizontal illuminance measurement receiver passes directly under the lamp. Characteristic illuminance measuring device. 2 The ratio of the maximum value to the minimum value of vertical illuminance is 3
In the following cases, the comparator output is low level,
The illuminance measuring device according to claim 1, characterized in that the analog switch is configured to be turned off.