JPS6012563B2 - distance detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a distance detection device for detecting the distance to a distant object.

Various distance detection devices have been proposed in the past, but they require mechanical means such as mechanically moving at least one of the two optical systems or vibrating a slit before or after the optical system. Met.

For example, Hakamako Sho 47-34352, Tokuko Sho 47-3337
The device shown in 4 etc. consists of a plurality of pairs of light-receiving elements, and the optical system of one is moved so that the same image is projected onto each light-receiving element by interchanging lenses in front of the pairs. This allows focus matching or distance detection to be performed.

Therefore, it was necessary to move the optical system by mechanical means. Therefore, it has drawbacks such as a longer time required to detect the distance. Also, accurate measurements cannot be made unless the accuracy of the moving parts is sufficiently high. An object of the present invention is to provide an improved distance detection device that does not require mechanical movable parts or a negative feedback system that includes the movable parts.

In order to achieve the above object, the distance detection device according to the present invention includes a first image sensor disposed a certain distance apart along a line perpendicular to the main optical axis, and a second image sensor with a large number of bits; a converging optical system disposed in front of each of the image sensors with their optical axes parallel to each other; an AD conversion circuit for AD converting the output of each of the image sensors; First and second shift registers each storing the distribution of the detected object image pattern on the sensor; initially, the output of the first image sensor is connected to the AD conversion circuit; the output of the AD conversion circuit is connected to the first image sensor; 1 shift register and then connect the output of the second image sensor to the A shift register.
a changeover connection switch connected to the D conversion circuit and connecting the output of the D conversion circuit to the second shift register; and when the output of the AD conversion circuit is sequentially input to the second shift register; A comparator that compares the outputs of each of the shift registers and generates a match output when they match; It consists of a counter that counts the time until the occurrence and detects the distance to the object to be detected.With this configuration, no mechanical means are used, but electrical means are used, so the distance detection time is determined by the clock. Determined by frequency,
This time can also be set to, for example, one skin second or less.

A more detailed explanation will be given below with reference to the drawings and the like.

FIG. 1 schematically shows the optical system of a device according to the invention. Parallel optical axis lens L located at a distance of 100 m
1 and L2 are arranged, and image sensors R1 and R2 are respectively arranged at a distance a behind them. Image sensor RI located behind the reference lens LI
In contrast, the number of bits of the image sensor R2 is increased. As shown in the drawing, an image of the object to be detected ○ located at a distance D apart is formed on each image sensor. The image of the object on the optical axis of LI is formed on the image sensor X that intersects with the optical axis of LI. However, the position of the image based on L2 differs depending on the distance D to the detected object. When D = target, L2 optical axis and R
The image is formed on the intersection point of 2, but as D becomes smaller, it shifts away from the intersection point. The magnitude d of this deviation is given by d=aso/D. Therefore, if d is known, D can be measured.
The image is formed on the 3rd element. On the other hand, R2 has 3#, turtle'? The image is formed on the groove'. In other words, a shift of two elements has occurred. By knowing the number of shifts in this way, the distance D can be known. The apparatus according to the present invention attempts to measure the distance to the object by electrically detecting the number of such shifts. FIG. 2 shows a schematic diagram of the configuration of the detection circuit.

R1 and R2 are the aforementioned image sensors. SWI is a switch that passes or stops the clock.
2 to SW5 are switches for switching between the RI system and the R2 system, and these all operate synchronously. Initially, it is in the a position, and when the RI scan is completed, it is switched to the b position. Although SWI to SW4 can actually be replaced with logic circuits and analog switches, mechanical switches will be described for ease of understanding. First SW
Since I is closed, the clock enters the image sensor RI through SW2,a. The image sensor sends out a signal of one bit per clock. When the image sensor is used in charge mode, an impulse-like current is generated, so a peak hold circuit P is used to extract the peak of the current. The peak value will be A/
It is D-converted and input into the shift register SRI in parallel.
Furthermore, the peak hold circuit P is reset every clock. A/D conversion converts N-bit digital data. This data is sent out from the shift register SRI and stored in the shift register SR2 through the switch SW4 until the next clock arrives. The number of bits of RI is K
In the case of bits, when the scanning of the RI is completed, KN bit data is sent to SR2. When the RI scan is finished, that is, when KN bit data is sent to SR2, SW2 to SW5 are switched to the b position, and the R
A clock starts to enter the shift register SR3, and digital data is sent to the shift register SR3. For example, an exclusive OR circuit is provided for each corresponding bit of SRI and SR3, forming a KN-bit comparator that outputs a signal only when all corresponding bits of SRI and SR3 are equal. Digital data is sequentially sent to SR3, and when it reaches the part SR3 where the same image as the image being imaged on RI' is imaged on R2, a signal is generated from the comparator to open SWI and clock Stop typing. Since the counter CI tells the number of clocks after SW2 to SW5 are switched from a to b, the contents of the counter when the clock stops are given as a function of distance. In order to perform automatic focusing using the distance information stored in this counter, a pulse motor may be used and compared with the distance information via a comparator, or an up-down counter and a pulse motor may be used. Note that since the counter stores distance information from infinity, it is sufficient to keep the photographic lens at infinity at all times and drive the photographic lens in synchronization with the signal from the comparator. Therefore, the distance to the object to be detected can be known and controlled based on the contents of the counter. Although digital processing has been described here, an analog shift register such as a charge-coupled device shift register may be used after peak holding, and an analog comparator may be used as the comparator.

The analog output from the image sensor is transferred to a charge coupled device (CCD) and a shift register (SR).
).

Since the CCD can shift the input signal according to the lock (up to the analog value), ``Similar to the above digital
If SR2 and SR3 are configured with CCD and SR, signals can be loaded into SR2 and SR3 without A/D conversion. The comparator may be an analog comparator, and the circuit operates in exactly the same way as when it is digital. As described above, the device according to the present invention is based on the fact that there is a contrast change on the object to be detected, and the light from the object creates a light pattern on each image sensor, so the surroundings are dark. When this occurs, the sensitivity of the image sensor decreases and detection becomes difficult, so the lens L
A light source that generates visible or infrared light is provided near the optical axis of I and parallel to the optical axis of LI.

To determine the ambient brightness, install another light receiving element or use RI.
Alternatively, the light source can be turned on and off automatically by detecting the average value output of the output level of R2. An example of such a configuration is shown in FIG.
SPDI is, for example, a silicon photodetector with a resistor RI or R.
2 or placed side by side in RI and R2.

When the object to be detected is dark, the photocurrent is small, so the collector current of Trl is small, and the potential at the connection point between RIO and the emitter of Trl decreases. Therefore, the comparator output becomes L level, the F/F is set, and the Q output of F/F becomes H level. B-1 is a buffer, and since Tr2 is turned on, the LEDI is lit. Of course, in order to keep the brightness of the LEDI constant, the LEDI may be driven with a constant current. R40CIO is a power supply reset circuit whose purpose is to generate a signal to reset the F/F after power is supplied by turning on SW'0. In this way, it is preferable to use a memory element such as an F/F so that the object to be detected is illuminated when it becomes dark and the LEDI is not turned off even if the photocurrent of the SPD 1 increases due to the illumination light. Further, the illumination light source is not limited to an LED, but may be a lamp or a strobe flash, and the intensity of light emission may be changed depending on the brightness of the subject.

As described above, according to the present invention, it is possible to provide a distance detector which has the advantage that the side distance time is extremely short due to purely electrical processing, and the distance can be measured by eight distances regardless of the surrounding brightness. Various modifications can be made to the embodiment apparatus described above in detail within the scope of the present invention.

For example, the lenses Lj and L2 may be cylindrical lenses. In short, the scope of the present invention extends to all of the claims, including any modifications thereof.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the optical system of the device according to the present invention, Fig. 2 is a block diagram showing the circuit configuration, and Fig. 3 is a schematic diagram of the auxiliary light emitting circuit used when the ambient brightness decreases. L2... Convergent optical system ○... Measured object position, R1, R2... Image sensor, CI
．．・・・．・, Force counter, SR1, SR2, SR3. ．． ．．
．．・・Shift register, 1/N……divider circuit, A/D…
...AD conversion circuit. Oh pith spear 2 figure size 3 meat

Claims (1)

[Claims] 1. A first image sensor arranged a certain distance apart along a line perpendicular to the main optical axis, a second image sensor having a larger number of bits than the first image sensor, and each of the image sensors. a converging optical system disposed in front of the image sensor with optical axes parallel to each other; an AD conversion circuit for AD converting the output of each of the image sensors; and a first optical system for storing the distribution of detected object image patterns on each image sensor. and a second shift register, initially connecting the output of the first image sensor to the AD conversion circuit, connecting the output of the AD conversion circuit to the first shift register, and then connecting the output of the first image sensor to the first shift register, and then connecting the output of the first image sensor to the AD conversion circuit. The output of A
a changeover connection switch connected to the D conversion circuit and connecting the output of the AD conversion circuit to the second shift register; a comparator that compares the outputs of each shift register and generates a match output when they match; and a time from when the AD-converted output of the second image sensor is input to the second shift register to when the match output is generated. Distance detection device consisting of a counter that counts the time and detects the distance to the detected object.