JPS625112A - Distance-detecting apparatus - Google Patents

Abstract

PURPOSE:To reduce distance measuring time, by locating an inverse integral indicating means on the input side of an integrating means and performing integration of the input signal at the time projection of 2 beams of light and inverse integration at the non-projecting time respectively. CONSTITUTION:An inverse integration indicating means 22 allowing inverse integration of the inverse integration value of an integrating means 25 to be performed at the non-projecting time of a light-projecting means 1 is installed. This means 22 feeds out to the means 25 through a switch 24 summation signal introduced from a gain control circuit 20 during the glowing period of the means 1 and a constant intensity of current i during the non-glowing period. Thus, in the means 25, the integration of the summation signal is performed at the glowing time and inverse integration of the integrated value of the summation signal by the current i at the non-glowing time. Thus, by performing the inverse integration taking advantage of the glowing time, reduction of the distance measuring time is attained.

Description

Detailed Description of the Invention (Field of Application of the Invention) The present invention relates to a distance detection device used in an automatic focus control device of a camera, etc. This invention relates to improvements in detection devices.

(Background of the Invention) FIGS. 8 to 10 show an example of an automatic focus control device having a conventional distance detection device of this type. In FIG. 8, the signal light projected from the light projecting element 1 passes through the light projecting lens 2,
The light is reflected by the object 3 surface, passes through the light receiving lens 4, and enters the light receiving element 5. As can be seen from FIG. 9, the light-receiving surface of this light-receiving element 5 is divided into two light-receiving sections 5a and 5bK, and based on each signal that is photoelectrically converted and output by the light-receiving section 5a + 5b, When the reflected light from the subject 3 enters the center of the light receiving parts 5a and 5b as a spot light S (see FIG. 9) as shown by the solid line in FIG. b) As shown in the photo-receiving section 5 a * 5
The amount of light received at each point b is approximately equal, and when the subject is located far away as shown in 3', the amount of light received at the light receiving section 5a is large and the amount of light received at the light receiving section 5b is large, as shown in Fig. 9 (b). The amount of light received is small, and when the subject is located close to the subject as shown in the key, the amount of light received at the light receiving section 5b is large and the amount of light received at the light receiving section 5a is small, as shown in Fig. 9 (c). Become. That is, when the amount of light received by the light receiving sections 5a and 5b is almost equal as shown in Fig. 9(a), the focus is on, as shown in Fig. 9(b), the front side is in focus, and as shown in Fig. 19(c), the focus is on the front side. It is determined that the focus is on the rear side, and if the focus is on the front side or the rear side, the photo-taking lens, which will be described later, is moved and at the same time the light receiving element 5 is moved (in the direction of the arrow in FIG. 8) to perform automatic focus control.

Next, specific operations during automatic focus control will be explained using FIG. 10. The light-receiving element 5 moves in conjunction with the movement of the photographing lens 6, that is, in conjunction with the rotation of the drive motor 7, via a cam or the like. are sensor amplifiers 8a and 8, respectively.
b1 Bypass filter 9a for direct current removal.

9b, analog switch 10a serving as a detection circuit;
10b and integrating circuits 11a and 11b are connected. The microcomputer 12 outputs a pulse signal to the light emitting element 1 and the analog switches 10a, 10b via the FFI circuit 13, and the light emitting element 1 emits pulse light according to this pulse signal, and the analog switches 10a, 10b
is turned on only during the period when the light projecting element 1 emits light, and supplies the signals A and B input from the sensor amplifiers 8a and 8b to the integrating circuits 11a and 11b via the bypass filters 9a and 9b. Integrating circuit 11a.

Signals A and B input to 11b are connected to the integration circuits 11a and 11.
After being integrated by b, they are output to the next-stage addition circuit 14 and subtraction circuit 15, respectively, and rA+BJ, rA-BJ
The calculation is performed and sent to the micro combinator 12. The microcomputer 12 outputs a sum signal (A
=+B) has reached a predetermined value, and whether or not the integral value of the difference signal (A-B) has exceeded a threshold value, for example, the focus can be determined as in-focus or out of focus (front side in focus, rear side in focus). In other words, when the sum signal (A+B) reaches the predetermined value V, and the difference signal (A-B) has not yet exceeded the threshold (■), it is determined that the focus is in focus, and conversely, the sum signal If the difference signal (A-B) already exceeds the threshold (■) before (A+B) reaches the predetermined value, it is determined that the focus is out of focus, and the automatic focus control signal N is immediately output to the drive motor 7, and the image is taken. When the lens 6 and the light-receiving element 5 are moved in an arbitrary direction, and the reflected light from the subject is almost equally incident on the light-receiving parts 5a and 5b, the movement of the photographing lens 6 is stopped, that is, the automatic focus control signal N is output. Stop the direction.

As described above, in the conventional example shown in FIG.
The configuration is such that signals A and B from b are simultaneously integrated, distance measurement information is calculated based on these two integrated values, and automatic focus control is performed. For this reason, the circuit that processes signal A (from sensor amplifier 8a to integration circuit 11a)
and a circuit for processing signal B (from the sensor amplifier 8b to the integrating circuit 11b), which increases the circuit scale and has the disadvantage that the characteristics (gain, offset voltage) of the two series must be made the same. Ta.

Therefore, in order to eliminate the above-mentioned drawbacks, the applicant of the present application has proposed that the signals A and B be processed in a time-division manner, that is, only one signal, for example, the signal A, is first sent to a known Miller integration circuit [predetermined 1
．． (see Figure 11 for time integration), then the sum signal (A+B)
proposed a device for inverse integration using
19 etc.). However, in the proposed device, the circuit scale is small and there is no need to match the characteristics of the two series.
This method has the problem that the distance measurement time is longer than that of a certain row type device.

(Object of the Invention) An object of the present invention is to provide a distance detection device that can shorten distance measurement time.

(Features of the Invention) In order to achieve the above object, the present invention provides an inverse integral instruction means that causes the integrating means to perform inverse integration of the integral value integrated when the light is emitted, when the light emitting means is not emitting light. is provided on the input side of the light emitting means, so that when the light emitting means emits light, the integral of the signal input from the light receiving means is obtained, and when the light emitting means does not emit light, the inverse integral thereof is calculated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiments of the Invention) The present invention will be described in detail below based on illustrated embodiments.

FIG. 1 is a block diagram showing one embodiment of the present invention. The same parts as in FIG. 10 are represented by the same symbols. 16 is an analog switch that is turned on when a high level signal is input from the output terminal O1 of the microcontroller and bit controller 17;
When the analog switch 16 is on, the light receiving section 5a
, 5b both receive the reflected light from the subject, and only the light receiving section 5a receives the light when it is off.

18 is a sensor amplifier, 19 is a bypass filter that removes direct current components such as sunlight, and 20 is for controlling the gain of the sum signal (A + B) or signal A that is input at that time according to the signal that is input via the inverter 21. , that is, output terminal 0. When a lower level signal is input (in this case, the sum signal (A+B) is input), it is output to the next stage at the same level, and conversely, a no-level signal is input. (in this case, signal A is input), the gain control circuit increases the gain to twice the level and outputs it to the next stage, and 22 is a light projection control circuit that is output from the output terminal 0° of the microcomputer 17. This is a switch circuit whose contacts switch according to a pulse signal, and when a high level signal is input, the contact a side is
When a low level signal is input, the contact side is selected by each contactor. Reference numeral 23 denotes a constant current source that generates, for example, a negative constant current i having a polarity opposite to that of the signals A and B, and is used when inversely integrating the sum signal (A + B) or the integral value of the two signals. 24 is microcombi data 17
terminal 0. An analog switch that turns on when a higher level signal is input, 25 is an integrating circuit, and terminal 0
It is reset by inputting the integral reset signal from 4. Reference numeral 26 denotes a microcombination unit 2-2, which has a counting section that counts pulses when the integral output reaches zero.
This is a comparator that outputs a signal at a low level.

Next, the operation will be explained using FIG. 2.3.

First, a high level signal is output from the output terminal 0° of the microcomputer 17 for one hour (see FIG. 2), and the analog switch 16 is turned on during this period. In this way, the analog switch 16 turns on (from
The reflected light emitted from the light emitting element 1 and returned from the subject is received by both the light receiving parts 5a and 5b, and is then sent to the sensor amplifier 1.
8 as a sum signal (A+B), and input to the switch circuit 22 via the bypass filter 19 and gain control circuit 20.

As described above, the switch circuit 22 operates in synchronization with the pulse signal (see Figure 2.3) output from the output terminal O1 of the microcomputer 17, that is, when a high-level signal is input (during light emission). Since the contact selects the contact a side when a low level signal is input (when not emitting light), the contact side selects the contact a side when a low level signal is input (when not emitting light), so the period when light emitting element 1 is emitting light outputs the phase signal (A+B) inputted from the gain control circuit 20, and a constant negative current i during the period when no light is emitted, to the integration circuit 25 via the analog switch 24. At this time, since a high level signal is being output from the output terminal O3 of the microcomputer 17, the analog switch 24 is on (see FIG. 3). Therefore, in the integrating circuit 25, as shown in FIG.
is integrated, and the integral value of the sum signal (A+B)1 is inversely integrated with a constant negative current i when no light is emitted. This inverse integral is used until the comparator 26 outputs a low level signal. That is, by outputting a low level signal in this way, the microcomputer 1
This is because the high-level signal output from the output terminal O8 of the switch 7 is inverted to a low-level signal, and the analog switch 24 is turned off.

Then, the time required for this inverse integration is counted by a counting section disposed within the microcomputer 17.

If the number of pulses at this time is P(A+l)l, then P(A+
1l) 1 is A/corresponding to the integral value of sum signal (A+B)t
This becomes the D conversion value. Note that the following P(All)g is the P6.
It is added continuously to the value of +phantom. The above-mentioned integration operation is performed continuously while the pulse signal within one hour is output, and the number of pulses Pa+s (P(All)1 + P(All) corresponding to the integral value of the sum signal (All) is )!...
) is determined, and the value is stored in the storage section within the microcomputer 17.

Next, 1 from the output terminal OI of the microcomputer 17
Since a low level signal is output for a certain period of time, the analog switch 16 is turned off during this time, and in this case, the reflected light returning from the subject is received only by the light receiving section 5a. Therefore, the signal A is output from the sensor amplifier 18, and this signal is passed through the bypass filter 19 to the gain control circuit 20 as two signals (because at this time, a high level signal is input via the inverter 21). ) is sent to the next stage switch circuit 22. Thereafter, as in the integration operation of the sum signal (All) described above, while the pulse signal is output at a predetermined period, the integration of the signal (2A) and the inverse integration using a constant negative current are performed. Number of pulses P at combiator 1f0 count section! □(P(
! A) l e P(2□)...) is found.

The number of pulses PALM and T2 obtained as above
．． is calculated in the micro combinator 17, and FA+l
=p, it is determined that the image is in focus, and otherwise it is determined that the image is out of focus. That is, the number of pulses FA+4 and T8. Distance information is determined based on. Then, based on the determination result obtained in this way, the microcomputer 1
An automatic focus control signal N whose pulse width is modulated is outputted from an output terminal Os of 7 to a drive motor 7. As a result, the rotational direction and rotational speed of the drive motor 7 are controlled,
The photographic lens 6 moves to the intended position.

Next, as shown in Figure 4, because the integral level of the sum signal (A + B) is high, the inverse integration of the integral value by the constant negative current i cannot be completely discharged within a predetermined time, and gradually There may be a case where the potential increases. Therefore, even if all the pulse numbers P (All) determined by the counting section in the microcombinator 17 are added up, the sum signal (
The exact number of pulses P(All) corresponding to A+B) cannot be obtained. Therefore, in such a case, it is necessary to inversely integrate the residual potential at the timing shown in FIG. That is, first, as described above, integration and inverse integration as shown in FIG.
□)' is obtained, and then the T1 time residual potential is inversely integrated (see FIG. 5), and the number of pulses during this inverse integration is added to the number of pulses P(All)'. As a result, the accurate number of pulses P(All) of the sum signal (All) can be obtained. Do the same for the two signalers. Once the accurate sum signal (All) and the number of pulses for the two signals are determined in this way, calculate the number of pulses P(,□) and P2□ in the same way as above,
Obtain ranging information.

In the embodiment of FIG. 1, a bypass filter 19 is provided in order to remove the direct current component (DC noise) due to external light such as sunlight that is present in the input signal as shown in the upper diagram of FIG. 6 (al). Note that the lower diagram in Figure 6(a) shows the integrated output state when an input signal with a DC component is integrated.However, as shown in the upper diagram in Figure 6 tbl, when light is emitted, influence the signal (if the signal is integrated, Fig. 6 tb>
(The result is an integral output state as shown in the figure below), which is not desirable. Furthermore, there are cases where DC noise cannot be completely removed. Therefore,
Generally, the DC noise value during non-occurrence is inversely integrated (see FIG. 6 (C1)).

The present invention is also effective in such a system. An example of such a case is shown in FIG.

The same parts as in FIG. 1 are designated by the same reference numerals.

The DC component from the gain control circuit 20 is inverted by the inverting circuit 27 (see the upper diagram in FIG. 6(C)), and the inverted signal and the constant current source 23 are sent to the adder circuit 28 arranged in the next stage. A constant negative current i is added, and the sum signal (All) and the two signals are inversely integrated using the resulting sum signal.

This makes it possible to obtain an integral output from which DC components are completely removed. That is, the integral output state is as shown in the lower diagram of FIG. 6 (C1).

According to the embodiments shown in Figs. 1 to 7, inverse integration is performed using the non-emission time when no operation was performed in the past, so the performance is significantly improved compared to the conventional one-line type device. It became possible to shorten distance measurement time. Also, the integration circuit 2
In order to guarantee the dynamic range of 5, usually temporary distance measurement,
In other words, the sum signal (A+B) is integrated for a predetermined period of time, then inverse integration is performed until the integral value reaches zero, the time required for this inverse integration is counted, and based on the count value... Determine the number of pulses of the pulse signal per distance measurement (in this example, the number of pulses output within one hour) (for example, set the integral value during pre-flash and the number of pulses per distance measurement to be constant). However, as mentioned above, since the configuration is such that inverse integration is performed every time the light is not emitted, the integration circuit 25 does not require a wide dynamic range, and the provisional distance measurement is performed. There is also the advantage that it is not necessary.

(Correspondence between Invention and Embodiment) In the embodiment shown in FIGS. 1 to 7, the light emitting element 1 serves as the light emitting means described in this explanation, the light receiving element 5 serves as the light receiving means, the integrating circuit 25 serves as the integrating means, and the microcomputer Reference numeral 17 corresponds to calculation means, and switch circuit 22 corresponds to inverse integration instruction means.

(Modification) In this embodiment, the sum signal (A+B) and signal A are integrated in a time-division manner, and distance measurement information is obtained from each integrated value.
Signals A and B are integrated in a time division manner, and each integrated value is, for example, 2A/(A+B).

The distance measurement information may be obtained by calculating (AB)/(A + B). Furthermore, although the present invention has been applied to a device consisting of one series, if it is applied to a device consisting of two series, although there will be some difficulties in terms of circuit configuration, it will be significant in terms of shortening distance measurement time, which is the gist of the present invention. It goes without saying that it is effective. (Effect of the invention) As explained above, according to the present invention, when the light projecting means is not projecting light, the inverse integral of the integral value integrated at the time of projecting light is calculated by the integrating means. A means for instructing inverse integration to be carried out is provided on the input side of the integrating means, so that when the light emitting means emits light, the integration of the signal input from the light receiving means is performed, and when the light is not emitted, the inverse integration is performed.
Since this is done separately, the distance measurement time can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a time chart thereof, Fig. 3 is a time chart of the main part, and Fig. 4 is a block diagram showing an embodiment of the present invention. Figure 5 is an enlarged time chart of a part of the case when the operation cannot be performed completely. Figure 5 is a time chart of each circuit in the normal state of Figure 4. Figures 6 (a) to (C1 are the input signal and integral FIG. 7 is a block diagram showing another embodiment of the present invention, and FIG. 8 is a diagram showing a part of a distance measuring optical system arranged in a general automatic focus control device. , Figure 9 (a) ~ (
c) is a diagram explaining the incident state of spot light from each subject position shown in FIG. 8; FIG. 10 is a block diagram showing a conventional automatic focus control device consisting of two series of circuits;
The figure is a diagram illustrating the integration state of two types of signals in a conventional automatic focus control device consisting of one series of circuits. DESCRIPTION OF SYMBOLS 1... Light emitting element, 5... Light receiving element, 17... Microcomputer, 22... Switch circuit, 23...
・Constant current source, 24...Analog switch, 25...
Integral circuit, 26... Combaret/, A. B...-signal, P(A+1), pz*...number of pulses.

Claims (1)

[Claims] 1. A light emitting means that repeats emitting and non-emitting light at a predetermined period, and receiving the light emitted from the light emitting means, reflected from the object to be measured, and measuring the distance of the object to be measured. A light-receiving means outputs two types of signals that vary depending on each other, an integrating means integrates the signal input from the light-receiving means and inverse-integrates the signal using a constant current, and a distance-measuring information is generated based on the time of the inverse-integration. In the distance detecting device, the inverse integral instructing means causes the integrating means to perform inverse integration of the integral value integrated at the time of light emitting when the light emitting means is not emitting light; A distance detection device characterized in that it is provided on the input side of a means.