JPS61240112A - Range finding apparatus - Google Patents

Abstract

PURPOSE:To make it possible to shorten a range finding time by dispensing with the detection of a summed signal at every operation of range finding information, by providing an unchangeability detection means and a summed signal holding means to a signal processing means. CONSTITUTION:A computer 9 being a signal processing means, analogue switches 14, 15, an integration circuit 17 and a comparator 19 operate range finding information on the basis of the sum of two kinds of signals inputted from a light receiving means 5 and either one of said signals. An operational processing part 9b being an unchangeability detection means for detecting that the sum signal does not continuously changes and memories (d), (e) are provided to the signal processing means. Further, memories (a), (c) each being a summed signal holding means storing the sum signal detected as unchangeability and outputting the same at every operation of range finding operation are provided. By this mechanism, the detection of the summed signal, when the summed signal is continuously unchangeable, is not performed and, therefore, a range finding time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in a detection device such as an automatic focus control device for a camera or the like, and is suitable for distance measuring a stationary subject.

(Background of the Invention) FIG. 6 shows a part of an active distance measuring optical system disposed in a general automatic focus control device.

The signal light projected from the light projecting element 1 passes through the light projecting lens 2, is reflected by the subject 3, passes through the light receiving lens 4, and enters the light receiving element 5. The light receiving surface of this light receiving element 5 is the sixth.
As can be seen from FIG. 7, it is divided into two light receiving sections 5a and 5b, and as shown by the solid line in FIG.
(see figure), the amount of light received by the light receiving sections 5a and 5b is almost equal as shown in Fig. 7 (1), and in such a state, it is determined that the subject is in focus, and as shown in the subject key. If the object is located far away, the amount of light received by the light receiving section 5a is large and the amount of light received by the light receiving section 5b is small, as shown in Fig. 7 (2), and the front side is determined to be in focus, and the object key is indicated. In contrast, when the light receiving part 5b is located close to the subject, as shown in FIG. 7(3), the amount of light received by the light receiving part 5b is large, and the amount of light received by the light receiving part 53 is small, and it is determined that the rear side is in focus. That is, in the automatic focus control device having the above-mentioned distance measuring optical system, the light receiving section 5a changes relatively depending on, for example, the subject distance.

The sum signal (A+B) of signals A and H output from 5b and one of the signals (or B) are integrated over a certain period of time, distance measurement information is obtained based on the integrated value, and as described above, focusing is performed. Determine out-of-focus (front and back focus), and if out-of-focus, move the focusing lens group and simultaneously move the light receiving element 5 (
(in the direction of the arrow in FIG. 6) to perform automatic focus control.

By the way, when distance-measuring a stationary subject continuously, for example, if the position of the spot light S on the light-receiving element 5 changes as shown in Fig. 8 (1) to (8). Then, the sum signal (A+B) used to obtain distance measurement information at each position will show the same value from (3) to (8) in FIG. However, in the conventional device having the above-mentioned configuration, the sum signal (A+B) is integrated every time even though it shows the same value, so it takes time to obtain distance measurement information. There was a problem that it took a while.

(Object of the Invention) An object of the present invention is to provide a distance detection device capable of solving the above-mentioned problems and shortening the distance measurement time.

(Features of the Invention) In order to achieve the above object, the present invention includes an invariance detection means for detecting that a sum signal is continuous and does not change; The signal processing means is provided with a sum signal holding means for storing and outputting the stored sum signal for each distance measurement information calculation for a certain period of time, so that the sum signal is not detected for each distance measurement information calculation. It is characterized by the following.

(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. 6.7 are denoted by the same reference numerals. 6 is, for example, a photographic lens that moves using a drive motor 7 as a drive source;
In conjunction with the movement of the photographing lens 6, the light receiving element 5 also begins to move (actually, it moves in conjunction with the rotation of the drive motor 7 via a cam, etc.). Reference numeral 8 denotes an analog switch that is turned on when a timing signal M is input from the micro combinator 9. When the analog switch 8 is turned on, both light receiving sections 58.5b receive reflected light from the subject; When off, only the light receiving section 5a receives light.

10 is a seven-inch amplifier, 11 is a bypass filter that removes the direct current component (external light component), and 12 is a control unit that controls 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 13. That is, when the timing signal M1 is a high level signal (in this case, the sum signal (A+B) is input), it is output to the next stage at the same level, and when the timing signal MI is a low level signal, it is output to the next stage. (In which case, the signal person is inputting) is a gain control circuit that increases the gain to twice the level and outputs it to the next stage, and 14° and 15 are input timing signals Me and Ms from the micro combinator 9. 16 is an analog switch that is turned on and off according to the timing signal M, which is a pulse signal input from the micro combinator 9; 17 is an integrating circuit; 18 is a negative 3. A constant current source that generates a constant current i, and is used when inversely integrating the sum signal (A+B) or the integral value of two signals. Reference numeral 19 denotes a microcombiner that has a counting section (described later) that counts pulses at the time 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). A comparator 20 outputs a signal at a low level. 20 is a drive circuit.

FIG. 2 shows a block diagram of the main parts arranged within the microcomputer 9. As shown in FIG. 9a is the sum signal (
A+B) or a counting section that counts the pulses generated in the pulse generating section shown in the quantum diagram from the start of the inverse integration of the two signals until the low level signal is input from the comparator 19, 9b is various memories and signals described later The arithmetic processing section, which performs distance measurement calculations and the like, is a memory, and the memory stores the number of pulses of the sum signal (A+B) during each distance measurement. The memory port stores the number of pulses of two signals during each distance measurement. The memory stores the number of pulses of the previous sum signal (A+B) stored in the memory. The memory tree stores the number of pulses added or subtracted by a certain value 2 to the number of pulses sent to the memory. When the number of pulses of the resulting sum signal (A+B) falls within a certain range (±2) consecutively, "1" is added to the memory, otherwise "0" is added. . The method is to store the value in memory a predetermined number of times (the next sum signal (A+B
If the same value continues, the sum signal (A+B) may not be integrated. The number of pulses of the sum signal (1+B) obtained during the fourth distance measurement is used as the preset number of times the distance measurement is expected to occur, and is used to count how many times the sum signal (1+B) is used.

Next, the operation will be explained with reference to FIG. First, the micro combinator 9 outputs a timing signal M1 to turn on the analog switch 8 for a preset hour. By turning on the analog switch 8 in this way, the light emitted from the light emitting element 1 and reflected light returning from the subject is received by both the light receiving parts 5a and 5b.
A sum signal (λ+B) is output from the senna amplifier 10.

The timing signal MI is input to the gain control circuit 12 as a low level signal via the inverter 13, and therefore the gain control circuit 12 receives the sum signal (Jinshi B) input via the bypass filter 11.
) is output to the next stage analog switch 14 at the same level. Also, at this time, it can be seen from Figure 3(a)5
The timing signal Mt is sent from the micro combinator 9 to
-M4 is output, so the analog switch 14 outputs the timing signal M! Accordingly, the analog switch 16 is turned on and off according to the timing signal M4, that is, the light emitting element 1
They each turn on in synchronization with the timing of the light emission. Therefore, the sum signal (A+B) output from the gain control circuit 12 is sent to the integration circuit 17 through the analog switch 14.16, and is integrated for one hour as shown in FIG. 3(b) (step 101). ). Like this T
o When the sum signal (A+B) is integrated in the time integration circuit 17, the microcomputer 9 outputs the timing signal M,
begins to be output, and this time the analog switch 15 is turned on. When the analog switch 15 is turned on, inverse integration is started by the negative 3 constant current i flowing from the constant current source 18 (see FIG. 3(b)), and a high level signal is output from the comparator 19 for this inverse integration. It will be rented until it is released. During this time (time required for inverse integration), the counting section 9a disposed within the micro combinator 9 counts the number of pulses generated by a pulse generating section (not shown) also disposed therein. If the number of pulses at this time is 8, the bird will receive an A/D conversion signal (A/D) corresponding to the integral value of the sum signal (A+B).
D conversion value) (step 102). The pulse number at this time is stored in the memory via the arithmetic processing section 9b disposed in the microcombi 9 (step 103).
).

When the number of pulses P0 is obtained by pre-distance measurement as described above, the number of pulses P. Based on this, an integration time suitable for integrating the sum signal (A + B) in the integration circuit 17 is set. In other words, when the distance to the subject and its reflectance are different, when the sum signal (A + B) is integrated over a certain period of time, the integrated value will vary greatly, exceeding the dynamic range that can be measured depending on the subject conditions at that time. (The integrated voltage of the sum signal (A+B) approaches the power supply voltage and becomes saturated). If the integral value of is high, the integration time is shortened, and conversely, if it is low, the integration time is lengthened. Therefore, the following calculation is performed in the micro combinator 9 (calculation processing section 9b) to determine the next integration time of the sum signal (A+B) (step 104).

Calculate the integral time using the cutting allowance (this time Tr = To −
(calculated by /9), the micro combinator 9 receives this T, time timing signal Mt# M2 +M
, outputs. As a result, the TI time sum signal (person + B)
(step 105), and then the timing signal M is output, so that the constant current iK''C is inversely integrated, and the integral value of the sum signal (A+B) is A/D converted to the number of pulses Pm+1. is obtained (step 106).The number of pulses Pk at this time.

is stored in the memory of the microcomputer 9 as before (step 107). In this case, the previous pulse numbers P and m stored in the memory are erased. When the above operations are completed, the microcombination controller 9 outputs the timing signals Mt and M+ again (see FIG. 3(a)). In this case, since the timing signal M1 is not output, the analog switch 8 is turned off, and the gain control circuit 12 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 5a, and two signals which are twice as many as the signal to be output are integrated (step 108), and then the timing signal Ms is output as described above. Integration is performed, and the pulse numbers P and A are obtained by A/D converting the integrated value of twice the signal person (step 109).

The number of pulses PEA at this time is stored in a memory port in the microphone computer 9 (step 110).

The number of pulses Ph+m (memory) obtained as above and the number of pulses P! Based on A (memory port), the micro combinator 9 performs the calculation (
P! A/Pm) (step 111) to determine in-focus or out-of-focus, and to determine the pulse number ratio P8□/Ph+m.
Accordingly, the pulse width of the automatic focus control signal N (see FIG. 1) to the drive motor 7 is modulated (PWM). As a result, the rotational direction and rotational speed of the drive motor 7 are controlled (step 112). In this embodiment, as shown in FIG. 4, Pzh/Ph1s is, for example, "0.8 to 1.
If it is within 2", it is determined to be in focus. Further, the number of pulses FA+1 stored in the memory is used to calculate the next integration time (one hour) (step 113).

By the way, as mentioned above, T due to the number of pulses P□1.

Once the time has been calculated, perform the same operation as above again (integrate the hourly sum signal (A+B) to find the number of pulses PA+l at this time, then integrate the two signals to find the number of pulses P!A). It is conceivable that the distance measurement information can be obtained by performing automatic focus control, but as mentioned above, if the pulse number PA + 1 continuously shows the same value twice, the distance measurement time will be longer. Such inconveniences arise. Therefore, in such a case, the sum signal (A+B) is not integrated every time, but the signal 2
The above problem will be solved if only the human integral is written in row 5. In order to solve the above-mentioned problems, the distance measuring operation will be explained below following step 113 in FIG.

After calculating the next (second) integration time (one hour), the arithmetic processing unit 9b in the microcomputer 9 determines whether the data in the memory (see Figure 2) is "F&" or not. (Step 114). 'As mentioned above, "1" is added to the memory when the pulse number PA+1 is within a certain range, and in this case, only the first distance measurement has been performed. It is "0". In this way, if the data to the memory is not "1", the process moves on to a judgment as to whether or not data (the number of pulses Pi+m from the previous or previous time) is stored in the memory (step 115). In this case, since only the first distance measurement was performed, nothing is stored in the memory, so the arithmetic processing unit 9b clears the contents in the memory (in addition, the memory at this time is set to "0" from the beginning). ”) (step 116), and then stores the data stored in memory 8 in memory 8 (step 117).
, Furthermore, the value obtained by adding the number of pulses X to the data stored in memory 8 (PA+1 + ”) is stored in memory 2 (
Step 118), the value obtained by subtracting the number of pulses X (Pk+,
') is stored in the memory (step 119).

When the above operations are completed, the process returns to the loop of step 105 in which the 6-hour sum signal (A+B) calculated using the previous pulse number FA+1 is integrated, and the second distance measurement is started. By the second distance measurement, it is determined whether or not it is located. In this case, since the number of pulses PA+1 found during the first distance measurement is stored in memory 8, the number of pulses PA+1 found during the second distance measurement (data in memory 1) is stored in memory 8. (steps 120 and 121), and if it is determined that the data is within the range 1 (the number of pulses PA + l If the relationship between each data is in the memory2>memory2>method tree), add ``1'' to memory (this time, ``1'' is added to memory = OK, so memory = 1) , the process moves on to determining whether the data to the memory has reached "ru" (step 123).
. In addition, if it is determined that there is a relationship of Memory I>Memory 2 or Memory A<Memory H, clear the contents to the memory,
Update tree data to memory (steps 116 to 1)
19). When it is determined whether the data stored in the memory has reached ``ro'' or not, if it is determined that the data has not reached ``ro'', the process returns to step 105 and the third distance measurement is started. If it is determined that the same value has been obtained repeatedly (to memory = n), the arithmetic processing unit 9b adds "1" to the memorand (step 124), and then the data in the memorand becomes r-J. A determination is made as to whether it has been reached (step 125).

At this time, since the memorandum data is "1", it is determined that "凰" has not been reached. Then, the next (1+1) distance measurement starts from step 108, that is, the sum signal (A+
Do not perform the integration of B), but perform only the integration of the two signals,
The distance measurement information for the +1st time is obtained based on the pulse number PffiA obtained next time and the pulse number PA+1 stored in the memory 8, and an operation for performing automatic focus control is started. Also,"
If it is determined that the distance has been reached, the data in the memory is cleared (step 126), the process returns to step 105, and the distance measurement starts from the first time.

According to this embodiment, when the value of the sum signal (A + B) continues 1 times in a row, the sum signal (A + B) is not integrated up to m times after that, and the value of the sum signal (A + B) is Since the integration is performed only for the distance measurement, the time required to obtain the distance measurement information can be shortened. Further, by not integrating the sum signal (A+B) in this way, the number of times the light projecting element 10 emits light can be reduced, which has the advantage of reducing power consumption.

(Correspondence between the invention and the embodiments) In this embodiment, the light projecting element 1 is the light projecting means of the present invention,
The light-receiving element 5 serves as a light-receiving means, the microcombination 1-9 and the analog switch 14 to the comparator 19 serve as signal processing means, the memory 8 serves as a sum signal holding means, and the arithmetic processing section 9b.

Memories 2 and 5 correspond to the unchanged detection means K, respectively.

(Modification) In this embodiment, a type of device that obtains ranging information based on the integral value of the sum signal and the integral value of one of the signals has been described. For example, one signal is integrated for a predetermined time, and then the It would be easy for those skilled in the art to apply this method to a type of device that performs inverse integration until the integral value reaches an initial level due to a signal, and obtains ranging information from the relationship between the time required for this inverse integration and the predetermined time. . Also, without using one signal A or signal B, the difference signal (A-B) between two signals A and B is used to find the integral value of the difference signal (A-B), and the sum signal (A-B) is calculated. The distance measurement information may be calculated from the integral value of B).

(Effects of the Invention) As explained above, according to the present invention, there is a constancy detection means for detecting that the sum signal does not change continuously, and a sum signal detected as being constant by the constancy detection means is stored, This is because the signal processing means is provided with a sum signal holding means that outputs the stored sum signal every time the ranging information is calculated for a certain period of time, so that the sum signal is not detected every time the ranging information is calculated. , it becomes possible to shorten distance measurement time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram of the main parts arranged in the microcomputer shown in FIG. 1, and FIG. 3 is the same (its time chart, Figure 4 shows an example of the calculated values by Microcombi Shima-Yu. Figures 7 (1) to (3) are diagrams showing the incident state of the spot light from each subject position shown in Figure 6.
Figures (1) to (8) are diagrams showing examples of changes in the position of the spot light on the light receiving element when a stationary subject is continuously measured. DESCRIPTION OF SYMBOLS 1... Light emitting element, 5... Light receiving element, 7... Drive motor, 9... Micro combinator, 14-16.
...Analog switch, 17...Integrator circuit, 1B...
・Constant current source, 9a... Cacunto section, 9b... Arithmetic processing section, I~T... Memory, A, B... Signal, PA4
4, P6 e Ps,...number of pulses.

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 signal processing means that calculates distance measurement information by calculating based on two types of sum signals input from the light receiving means in a time-sharing manner and one of the signals or the difference signal thereof. , a constancy detection means for detecting that the sum signal does not change continuously; and a constancy detection means for storing the sum signal detected as being constant by the constancy detection means, and for a certain period of time, using the memorized sum signal as ranging information A distance detection device characterized in that the signal processing means is provided with a sum signal holding means for outputting each calculation.