JPS5866886A - Water drop detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applied to automobile 70/togafus, etc.

As shown in FIG. 1, a conventional device of this type includes a light emitting device 11 such as a light emitting diode on one side of a glass plate 10.
It is known to optically detect the presence or absence of water droplets 15 adhering to the cover plate 10 by installing a light receiver 121 such as a photodiode on the other side to receive the emitted light. The photodetection area of light receiving @12 is shown in Figure 2 (A
), there is a water droplet 1 in it.
The shadow 21 of 3 is f! & Since the received light level will fluctuate if it is shaded, the presence or absence of water droplet adhesion is detected by detecting the O fluctuation. However, this water droplet detection device has a drawback that, where the area of the photodetection region 200 is 81 and the area of the shadow 21 of the water droplet 1s is P, the detection sensitivity is low for the amount of fluctuation in the received light level. If the area of the photodetection area 200 S\l:Ji2 is made smaller as shown in Figure (B), the amount of variation in the light reception level for one water droplet will increase and the sensitivity will decrease.

The present invention improves these conventional drawbacks and
The purpose is to provide a water droplet detection device that can detect water droplets adhering to a glass surface with high sensitivity. This will be explained in detail below.

sWA is a boot representing the basic configuration of the water droplet detection device of the present invention? In the figure], 10 is a glass@, 15 is a water droplet, 50 is a light emitter, 51 is a light emitting element such as a #i light emitting diode, 52a is its driving circuit, 35 is a light detector, 556-55
．． Fi photoelectric conversion element, 34 is a multiplexer, 55 is an amplifier, 56 is a band pass filter, 67 is a Hiro detection circuit, 5
8 is a discrimination circuit, and 39 is an output terminal.

The light emitter 50 emits an optical signal for detecting water droplets from one side of the glass plate 10 toward the water droplet adhesion observation area.
o6. It includes a light receiving element 51 and its driving circuit 52.

The light-emitting cable s1 is driven by a rectangular wave signal to reduce the influence of external light, and emits a pulsed light signal as shown in FIG. 14 (A), for example.

The photodetector 55 is constructed by arranging a plurality of photoelectric conversion elements 556 to 55 in a line close to each other, and each photoelectric conversion element 558 to 55 is arranged in a line with nothing attached to the glass surface.
The glass plate 10t is mounted at a position where it can receive the transmitted light from the light emitter 50 so that the output level of the glass plate 35s is almost uniform.

The multiplexer 54 sequentially switches the input channels in one run cycle to convert the photodetector SSO to each photoelectric conversion element 55.
・It reads out ~55% of the output as a time-series signal, and is 1L.
The read signal is applied to a detection circuit 37 via an amplifier 35 and a bandpass filter 56. The center frequency I of the bandpass filter 56 is set to the frequency of the light emitting element 31 drive signal, and the influence of external light is removed here.

If there are no water droplets attached to the glass plate 10, each photoelectric conversion element 5ea-55% of the photodetector 35 is irradiated with TL energetic energy, so the output signal of the bandpass filter 56 is, for example, the fourth The output of the detection circuit 37 to be determined by its envelope -me is, for example, as shown in Figure 4C.
As shown in D), the signal waveform becomes less uneven. On the other hand, as shown in FIG. 4 (J), the photoelectric conversion element of the photodetector! +5a-55% (8m16 in the IQ example. The size of each photoelectric conversion element is 15-X4mm) When water droplets 130 images 41 to 45 appear at the positions shown in the figure for K, the lens effect due to the water droplets, Jl Multiplexer 54
The zero output increases at the water droplet adhesion position and decreases at the surrounding area.
The outputs of 7 have signal waveforms including irregularities with large amplitudes at the 4th E (ff) and (F), respectively. Therefore, by determining the variation in the output of each photoelectric conversion element outputted from the detection circuit 57 by the determination circuit 58, the presence or absence of water droplet adhesion can be detected.

In the present invention, an arrangement of a plurality of charge conversion elements each having a relatively small area of light detection area is used as a photodetector, and the detection of adhering water droplets is affected by variations in the output of each element. You can relatively clear your field of view, and you can see #I
A small amount of water droplets adhere to the ll field of view, and the output of the electro-photoelectric conversion element fluctuates greatly. Therefore, it is possible to detect water droplets with high sensitivity.

In addition, if the influence of external light can be ignored, the KO1 light-emitting element S
1 may be driven by a DC signal to irradiate a continuous optical signal onto the glass plate. In this case, the bandpass filter 56 and the detection circuit 37 are omitted.

FIG. 5 is a block diagram of the main parts of the device according to the embodiment of the present invention.
0 Expanded emission wavelength λ, bait 950%, emission power pot=S
mW light emitting diode, 51 is a four-way LED drive, 52 is a pulse oscillator with a pulse repetition frequency of 7 KHz, 56 is 1
Photodiode array with 6 photoelectric conversion elements arranged in a row, 54ri'/a frequency divider, 55 is 4-bit power one-ta%
56d16 channel multiplexer, 57 is preamplifier, 58 is center frequency /c a117 KHz'Q
,, IO bandpass filter, 59 is the detection tltWA16
．． 60 is the buffer 1 amp, 61 is the cutoff frequency rtl*
ta-5 to 10Jf, bypass filter, 62 is low video monitor terminal, 6Sd, quindo converter, 6
Integrator h with 4c time constant vm5T~107' (f is 1 scan time of photodiode array 5!1) 651
1:2 y Z regulator, 66 is a variable resistor for adjusting the detection level, 67 is a detection signal output terminal, 68 is a regulator, 69 is a Hiro Riggle filter, and iG is a power input.

In the figure, a light emitting diode 50 is an LED drive circuit 5.
The output light is driven by a rectangular wave with a pulse repetition frequency of 71M, and a portion of the emitted light passes through the gas and enters the photodiode array 53. A 4-bit counter 55 is counted up using a signal obtained by dividing the output of the pulse oscillator 52 by S, and a switching signal for a multiplexer 56 is generated. In this case, %1 switching speed of charging conversion element −
at1ssb1 scan time T(a, 16g) is 18
To) at Tsuru 8), photodiode array 55 at each cycle
C) The output of each photoelectric conversion element is read out sequentially and sent to the preamplifier 5.
7 and a bandpass filter 5at- to the detection (9) path 59.

The total gain of preamplifier 57 and bandpass filter 58 is approximately 60 dB.

Detection circuit 5? It is applied to the low video monitor terminal 62 and the high bypass filter 61 through the output line buffer 1 (60%). This bypass filter 61ha rattan 4Ii1
<D) This is for cutting the DC component of the signal shown in (7). Therefore, for example, FIG. 4(D).

(JP) shows the nine signal expansion #I6 diagrams (1) and (j
The waveform is shaped into a signal as shown by the curve M and *aH in i).

The window comparator 63 compares the input signal with two threshold values and sets its output to "1" when the input signal level deviates from the area (quindo) between the two threshold values. ．． If μ2, then Figure 6 (A),
Signal a1. shown in (B). The wind turbine parator output of #fi is shown in FIG. 6(C).

(D) K will be shown. This window comparator 6
The output of s is inputted to the integrator 64JIC, and the integrator corner detection level is compared with the comparator 65. When the integrated output becomes larger than the detection level, the water droplet detection signal changes from high level to low level. In the example shown in Fig. 6, in the case of the signal shown in Fig. 6 (C), the integral output line is zero and the water drop detection signal is at a high level, but in the case of the signal shown in Fig. 6 (D), the integral output line 4 is expanded. As shown in Figure <N), when the detection level is higher than #1, the water droplet detection signal becomes a critical level.

Of course, the numerical values of each element mentioned above are just examples and can be changed as appropriate.

FIG. 7 shows the water droplet detection device 1 of the present invention which is used to electrically detect raindrops adhering to the windshield of an automobile and to operate the wiper
This is a diagram showing the arrangement of photodetectors, etc. when controlling start-up or absentee work time. 6) A light emitting diode 72 and its O drive circuit 7s are housed in the loop A-71 of the door 70, and the windshield is connected to the windshield. A light signal 75t- is irradiated near the upper center of 74. A photodetector 76 is fixed at a light irradiation position via a prism 77, and its detection output is applied via a transparent conductor 78 to a signal processor 79 attached to the roof surface of the vehicle interior.

The grism 77/ri is for efficiently guiding the irradiated light from the light emitting diode 72 to the photodetector 76, and is rounded to reduce the influence of external light such as sunlight.
It is desirable to provide a color filter that transmits only two emission wavelengths. Further, in order not to give a sense of discomfort to the driver, it is preferable that the light detection @74 be installed behind the rearview mirror 80.

As described above, the water droplet detection device of the present invention detects the presence or absence of water droplets attached to a transparent or semi-transparent plate such as a glass plate by detecting the presence or absence of water droplets on a transparent or semi-transparent plate, which is composed of a plurality of photoelectric conversion elements. Since the detection is performed using a device and the variation in the output of each element is detected, it is possible to detect even a small amount of water droplets in a relatively wide field of view, making it possible to detect the adhesion of water droplets with high sensitivity.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a conventional water droplet detection signal, Fig. 2 is an explanatory diagram of its operation, Fig. 5 is a block diagram showing the basic configuration of the water droplet detection device of the present invention, and Fig. 4 is a diagram illustrating its operation. Explanatory diagram,
Fig. 5 is a schematic diagram of the main parts of the device according to the present invention, No. 6E.
is an explanatory diagram of its operation, and Figure 7 is a diagram showing the operation of this device. FIG. 3 is a diagram illustrating the arrangement of photodetectors and the like when applying the jj. 10 is a glass plate, 13 is a water droplet, 50 is a light emitter, 51 is a light emitting element%, 52 is an LED drive circuit, 33 is a line photodetector, 5
! I@~■1 is a photoelectric transducer, 54 Hiro multiplexer, s5 is an amplifier, 56 is a band pass filter, 57 is a detection circuit, 5@ is a discrimination circuit, and 59 Hiro is an output terminal. Patent Applicant Fujitsu Ten Ltd. (1 person) Representative Patent Attorney Tamamukyu (5 persons) Figure 1 Figure 2 Figure 4 Figure 6 Figure 7 Figure 7 / Q'-80 6 74 ・・1. /,,.

Claims (1)

[Claims] In a water droplet detection device that optically detects the presence or absence of water droplets adhering to a transparent plate or a translucent plate, the transparent plate has a light emitting device that irradiates light onto the semitransparent plate, and a light emitting device that emits light from the light emitting device. Sakama light consists of a photodetector that transmits a large amount of light through a semi-transparent plate and detects it with multiple photoelectric conversion elements, a multiplexer that extracts the detection output of each photoelectric conversion element of the cough photodetector as a time series signal, and the output of the multiplexer. 10. A water droplet detection device comprising a discriminating circuit and a device for detecting the level of the output of each photoelectric substitution element included in the photoelectric displacement element to determine the presence or absence of water droplets.