JPS61240113A - Range finding device - Google Patents

Abstract

PURPOSE:To obtain accurate range finding information, by controlling the respective gains of signals, which are inputted to an operation means in a time sharing manner, in a cooperated state. CONSTITUTION:The summed signal (A+B) inputted to a gain control circuit 100 is inputted to a multiplier part 100g and a level discrimination part 100c and it is discriminated whether the sum signal (B+B) is higher than a saturation level to set the gain of a setting part 100d. When it is discriminated that the signal (A+B) is higher than the saturation level and a gain for suppressing said signal to 0.5 times is set to the gain setting part 100d, the set gain is outputted to the multiplier part 100g which, in turn, corrects the signal (A+B) on the basis of said gain to output the same to a switch 11 as a sum signal (A+B)/2. The gain at this time is held to a hold part 100e and outputted to a multiplier part 100h as a twofold gain by an amplifier part 100f. The signal A inputted to the circuit 100 is inputted to the multiplier part 100h and corrected on the basis of the gain of the amplifier part 100f to be outputted to the switch 11. As mentioned above, the gains to the signal (A+B) and the signal A are made the same and accurate range finding information can be obtained.

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. It is related to the improvement of the detection device.

(Background of the Invention) FIG. 4 shows an automatic focus control device having this type of distance detection device, which was filed on the same day by the applicant of the present invention.

In FIG. 4, 1 is a light projecting element, 2 is, for example, a photographic lens that moves using a driving motor 3 as a driving source, and a light receiving element that is composed of light receiving parts 4a and 4b in conjunction with the movement of the photographic lens 2. 4 also begins to move (actually, drive motor 3
(moves via a cam etc. in conjunction with the rotation of). Reference numeral 5 denotes an analog switch that is turned on when a timing signal M is input from the micro combinator 6. When the analog switch 5 is turned on, both light receiving sections 4a and 4b receive reflected light from the subject. When off, the light receiving section 4a
only the light will be received. 7 is a sensor amplifier, 8 is a bypass filter that removes DC components (external light components), 9
controls the gain of the sum signal (A+B) or signal A that is input at that time according to the signal input via the inverter 10, that is, when the timing signal M is a high level signal (in this case, the sum signal (A+B) input)
is output to the next stage at the same level, and when the timing signal M is a low level signal (in this case, the signal person is inputting it), the gain is increased to twice the level and output to the next stage. The gain control circuit 11.12 receives the timing signal M! from the micro combinator 6. , 13 is an analog switch that turns on when Ms is input!
A timing signal M4 is a pulse signal inputted from the microcombi 1 to 6; an analog switch is turned on and off accordingly; 14 is an integrating circuit; 15 is a constant current that has the opposite polarity to the signals A and B, e.g., generates a negative constant current. It is used when inversely integrating the sum signal (Jinshi B) or the integral value of two signals at the source. 16 is a microcontroller with a counting section that counts pulses when the sum signal (A+B) or the inverse integration of the integral values of two signals is completely completed (when the integral output reaches zero). 6 is a comparator that outputs a low level signal; 17 is a drive circuit;

Next, the operation will be explained with reference to FIG. First, the microcombination unit 6 sends a timing signal M to integrate the sum signal (A+B).

The analog switch 5 is turned on for a certain period of 13 hours. When the analog switch 5 is turned on in this way, light is emitted from the light emitting element 1, reflected light returns from the subject, is received by both the light receiving parts 4a * 4b, and is sent as a sum signal from the sensor amplifier 7. (A+B) is output. Also, the timing signal M is inputted to the gain control circuit 9 as a low level signal via an inverter, so the gain control circuit 9 inputs it via the bypass filter 8. Sum signal (A+B)
is output to the next stage analog switch 11 at the same level. At this time, as can be seen from Fig. 5+8), the micro combinator 6 sends timing signals M*,
Since M4 is output, the analog switch 11 is turned on and off according to the timing signal M, and the analog switch 13 is turned on and off according to the timing signal M, that is, the light emitting element 1
They each turn on in synchronization with the 0 emission timing. Therefore, the sum signal (A+B) outputted from the gain control circuit 9 is supplied to the integrating circuit 14 through the analog switch 11.13, and is integrated over time T8 as shown in FIG. 5(b). In this way, T8 time integration circuit 1
When the sum signal (A+B) is integrated at step 4, the micro combinator 6 starts outputting the timing signal Ms.
This time, the analog switch 12 is turned on. When the analog switch 12 is turned on, the negative constant current i flowing from the constant current source 26 starts inverse integration (see Fig. 5 (bl)
), and this integral is used until the comparator 16 outputs a low level signal. During this time (the time required for inverse integration), the counting section disposed within the micro combinator 6 counts the number of pulses generated by the pulse generating section also disposed inside. If the number of pulses at this time is PA+lI, then PA+1 is the sum signal (A+B)
It becomes an A/D conversion signal (person/D conversion value) corresponding to the integral value of . When the above operations are completed, the micro combinator 6 again outputs the timing signals M, , M4 (see Fig. 5+!>). In this case, the timing signal M1 is not output, so the analog switch 5 is off.
Also, the gain control circuit 9 is switched to a mode in which the gain of the input signal is doubled. Therefore, in this case, the light is received only by the light receiving section 4a, and a signal twice as many as the output signal is integrated, and then the timing signal M is output as described above, so inverse integration is performed at a constant current i. , the number of pulses obtained by A/D converting the integral values of the two signals is obtained.

The micro combinator 6 performs calculations (P!A/PA+l) as shown in FIG. At the same time, the drive motor 7
The pulse width of the automatic focus control signal N (see FIG. 4) is modulated (PWM). This controls the rotational direction and rotational speed of the drive motor 7.

In the above-mentioned device, the distance measurement information is obtained based on the integral values of the sum signal (A+B) and the signal AA, which are output in a time-division manner, so that the offset voltage can be more effectively canceled. However, when the subject is close, that is, when the reflected light from the subject is strong, the output level of the light receiving sections 5a and 5b becomes high, and for example, the level of the sum signal (A+B) input to the integrating circuit 14 increases. becomes high, and the integrated output of the CC phase sum signal B) approaches the power supply voltage and may become saturated. In order to eliminate this inconvenience, when the level of the input sum signal (A+B) reaches the saturation level (the level at which the integral output of the integrating circuit 14 is saturated), the gain control circuit 9 inputs 1, I
Instead of outputting it at the same level as mentioned above, it is conceivable to install a means of gain control (suppressing the level of the sum signal (Jinshi B) so that it does not exceed the saturation level) and outputting it to the next stage. . However, if the above-mentioned means are provided alone, a problem arises in that accurate ranging information cannot be obtained. That is,
The sum signal (Jinshi B) is suppressed at a certain ratio depending on the level, but since the levels of the two signals have not reached the saturation level, they are output to the next stage without being suppressed, and the signals differ in this way. This is because distance measurement information is obtained based on each integral value integrated by the gain.

(Objective of the Invention) An object of the present invention is to solve the above-mentioned problems and provide a distance detection device capable of obtaining accurate distance measurement information.

(Characteristics of the Invention) In order to achieve the above object, the present invention provides a method for determining the gain and time of the first input signal according to the level of the first input signal among the signals input to the calculation means in a time-division manner. A gain control means for setting the gain of a signal inputted later with a delay is provided at a stage before the calculation means, so that the gain of each signal inputted in a time-sharing manner is controlled in conjunction with each other. It is characterized by

(Example of the invention) Hereinafter, the present invention will be explained based on illustrated embodiments.

1 and 2 are block diagrams showing one embodiment of the present invention. The same parts as in FIG. 4 are denoted by the same reference numerals and their operations are also the same, so they will not be described here. 100a, 10
0b is the contact a when the timing signal M1 is input as a low level signal from the inverter 10 (at this time, the sum signal (A+B) is input from the bypass filter 8), and the timing signal M is input. 100c is a selection switch that selects each contact (signal A is input at this time), and 100c is a selection switch that determines the level of the input sum signal (A+B) and selects the next stage gain setting section 100d. As shown in Figure 3, in the level discrimination section that sets the gain, if it is determined that the gain is lower than the saturation level H, the amplification factor is set to 1, and if it is determined that the gain is higher, it is set to the height of the level at that time. Set the amplification rate (suppression rate) accordingly. 100e is a hold section that holds the gain set to 100dK in the gain setting section, 100f is an amplifier section that outputs the gain held in the hold section 100C as a double gain, and 100g
100h is a multiplication unit that corrects the sum signal (A+B) based on the gain input from the gain setting unit 100d, and 100h is a multiplication unit that corrects the signal amplitude based on the gain input from the amplification unit 100f. The gain control circuit 100 is composed of the aforementioned selection switch 100a to the multiplication section 100h. Note that the inputter 10 shown in FIG. 2 is omitted, and the timing signal M1 outputted from the micro combinator 6 is directly used as the selection switch 100a,
It may be configured such that it is supplied to b. However, in this case, when the timing signal M is input, it is necessary that the selection switches 100a and 100b select the contact point a.

Next, the operation will be explained. When the sum signal (A+B) is input from the pass filter 8 to the gain control circuit 100, the analog switch 1 is input from the inverter 10.
00aKci- level signal is input, so contact a
is selected, and the sum signal (A + B) is sent to the multiplier 100.
g and input to the level determination section 100c. Then, the level discriminator 100c detects the sum signal (A
+B) is higher than the saturation level H or not, and the gain of the gain setting unit 100d is set.

Here, a case will be described in which the current level is determined to be higher than the saturation level H by the level determining section 100c, and a gain is set in the gain setting section 100d to suppress it to, for example, "0.5 times". Since the gain set in the gain setting section 100d is output to the multiplication section 100g, the gain set in the gain setting section 100d is outputted to the multiplication section 100g.
0, g is the sum signal (
A+B) corrected ((A+B)/2)L, sum signal (A+B
)/2 and is output to the analog switch 11 via the selection switch 100b. On the other hand, the gain at this time is held in the hold section 100c, and is outputted to the multiplication section 100h as a gain c2 times by the next stage amplification section 100f.

Next, the signal person inputs the signal to the gain control circuit 100, but in this case, since the contact point is selected by the analog switch 100a, the signal person inputs the signal to the multiplier 100h. When the signal person is input, the multiplier 100h corrects the signal person based on the gain input from the amplification unit 100f (A・(0,5X2))L, and selects the input signal as it is as the signal person, that is, in this case, selects the input signal as it is. 10
- Output to analog switch 11 via Ob.

In this way, since the gain for the sum signal (person B) and the gain for the signal person are made the same, accurate ranging information can be obtained. That is, for example, the sum signal (A
If the level of signal B) is very high and the level of the signal person is low, in other words, if the level of signal B is high,
If you set the gain (using the calculation method shown in Figure 3) at the level of the sum signal (Jinshi B), and then set the gain using the same method shown in Figure 3 at the level of the two signals, the higher level Only the sum signal (A+B) is suppressed and distance measurement information is obtained based on each signal corrected with different gains, resulting in incorrect distance measurement information. However, as mentioned in 5 above, first Since the gain of the sum signal (A+B) and the gains of the two signals are set according to the level of the input sum signal (A+B), it is possible to eliminate such inconvenience.

(Correspondence between the invention and the embodiments) According to the present embodiment, the light projecting element 1 is the light projecting means of the present invention.
The light receiving element 4 corresponds to a light receiving means, the micro combinator 6 corresponds to a calculation means, and the gain control circuit 100 corresponds to a gain control means.

(Modified Example) In this embodiment, the sum signal (A+B) and the signal A are integrated in the same direction in a time-sharing manner to obtain distance measurement information for each integrated value. B is integrated in the same direction on a time-sharing basis, and each integral value yields, for example, 2A/(
A+B), (A-B)/(A+B) may be calculated to obtain ranging information, or one signal person or signal B
The integral value of the difference signal (A-B) is obtained by using the difference signal (person-B) between the two signals A and B without using , and as described above, (
The distance measurement information may be obtained by calculating Person-B)/(A+B). Also, a device of the type that integrates one signal for a predetermined period of time, then inversely integrates one signal using a sum signal until the integrated value reaches an initial level, and obtains ranging information from the relationship between the time required for this inverse integration and the predetermined time. It is also possible to apply the present invention to. Furthermore, even in a type of device where the level of the two signals is higher than the sum signal (A + B) at close range, if the configuration is designed in advance so that the signal person is output first, the same effect can be achieved. Applicable.

(Effects of the Invention) As explained above, according to the present invention, the gain and time of the first input signal are determined according to the level of the first input signal among the signals input from the light receiving means in a time-division manner. A gain control means for setting the gain of the other signal that is input with a delay is provided in the previous stage of the calculation means, so that the gain of each signal that is input in a time-sharing manner is controlled in conjunction with each other. , accurate ranging information can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a gain control circuit showing an embodiment of the present invention, FIG. 2 is a block diagram of an automatic focus control device having a distance detection device, and FIG. Figure 4 is a block diagram showing the automatic focus control device with a distance detection device, which was filed on the same day by the same applicant, Figure 5 is its time chart, and Figure 6 is the calculated values by the micro combinator as well. It is a figure showing an example. DESCRIPTION OF SYMBOLS 1... Light emitting element, 4... Light receiving element, 14... Integrating circuit, 15... Constant current source, 6... Microamp; -/, 100... Gain control [Ijl, 10
0a, 100b"・selection switch, 100c...level discrimination section, 100d...gain setting section, 100e・-
・Hold section, 100f...Amplification section, 100g, 10
0h - multiplication section, A, B...signal.

Claims (1)

[Claims] 1. A light projector that emits light toward the distance measurement target, and a light receiver that receives the reflected light from the distance measurement target and outputs two types of signals that relatively change depending on the distance of the distance measurement target. and a calculating means for calculating distance measurement information based on signals inputted from the light receiving means in a time-divided manner, the first of the signals inputted to the calculating means in a time-divided manner. The method is characterized in that a gain control means is provided at a stage before the calculation means for setting the gain of the first input signal and the gain of the later input signal with a time delay according to the level of the input signal. Distance detection device.