JPS59123810A - Automatic focus control device - Google Patents

Abstract

PURPOSE:To suppress a picture blur to the minimum and to obtain a stable picture by controlling a focus in a distance measuring range of the whole first, in a pupil dividing method, and switching to a narrow distance measuring range of a high contrast of a photoelectric element. CONSTITUTION:As for an output of each photoelectric element of a photodetecting array D, the same signal is stored in shift registers R1, R2 through a transfer device T. An, An+1, Bn and Bn+1 are transferred to algorithm processors P1, P2 by a clock from cables K7, K8. Basing on an S value of two groups of signals, the first extent of shift corresponding to the minimum value of S in all areas of the photoelectric element is derived by the P1, and the second extent of shift by which a difference of adjacent output signals of A1-An or B1-Bn corresponds to the minimum value of S in a small section centering around the maximum point is derived by the P2, compared with a reference value by a selector V, and a lens L0 is controlled by the selected first or second extent of shift.

Description

[Detailed Description of the Invention] The present invention is a built-in optical device such as a video camera or a camera.
Each time the specific person moves, the background changes and the in-focus state changes, resulting in a drawback that the focus of the specific person (main subject) changes each time, causing screen shake.

The present invention has been made in view of the above, and by configuring the focus control means to be switchable depending on the focus state of the main subject, once the main subject is in focus, the focus control means can be switched. , the distance measurement range for focus control is switched to a narrower distance measurement range centered on the output signal of the point where the difference between adjacent output signals of at least one of the photoelectric elements is the largest among the entire distance measurement range up to that point. The focus control is performed according to the focus state within the narrow range-finding range, and even if the background changes, focus control is not performed unless the focus state within the narrow range-finding range changes.
The main purpose of this is to minimize screen shake and provide a stable image.

That is, specifically, the present invention provides first and second photoelectric elements of a pair of photoelectric elements.
, and at least one output signal of the first and second output signals facing each other in each shifted state, based on the above-mentioned equation (1) or (2), for example. Multiply the gradient value by the value of the difference between the first and second output signals at the gradient value setting point to find the total sum value, and calculate the shift amount when the sum value becomes zero. As a shift amount of 1, the first shift amount of the pair of photoelectric element groups is
and a second output signal, the other output signal is relative to the output signal of a subsection consisting of a plurality of photoelectric elements centered on the photoelectric element where the adjacent output signal value of at least one of the output signals is largest. As above, for example (1)
Using the formula or formula (2), calculate the gradient value of at least one of the first and second output signals facing each other in each shift state in the subdivision, and the first and second output signals at the gradient value setting location. A signal comparator that outputs the smallest shift amount among the shift amounts for which the sum of the values multiplied by the difference value of the two output signals becomes zero as the second shift amount, and a second shift amount of the signal comparator. 1, a second shift amount, and a preset reference amount, and selects the second shift amount only when the first shift amount is within the reference amount range.
and the second shift amount, and a controller that drives and controls the electric motor in accordance with the defocus amount that is set according to the shift amount output by the selector. That is.

Hereinafter, the present invention will be further explained in detail with reference to the accompanying drawings.

For the purpose of explanation, FIGS. 4 and 6 and FIGS. 5 and 7 show that the output signals of the same subject image are compared and processed by the signal comparator having the two comparison processing means for the whole and sub-sections. The graphs shown in FIGS. 4 and 5 are graphs for explaining each shift state and a part of the processing results.
In the state t), the photographer decides the subject to be photographed, performs focus control on the main subject of the subject, and focuses on the main subject, for example,
Each n number (corresponding to the image part of each output signal AJ4 to A7 on the screen) that captures the light intensity distribution of each subject image when only the background of the main subject changes significantly while the main subject is almost in focus (for example, 1 each relative to an appropriate location in the output signal of 24 each)
0 pieces of data (A1-A1a and B1-B1 (1) are only supplemented for convenience, and furthermore, the amount of change in focus corresponding to one shift in this graph is determined from optical characteristics, for example, a change of 2 m/m. do.

Therefore, the present invention first captures the state of the graph [4-1] in Fig. 4 and performs focus control, and then inputs the output signal in each shift state of Fig. 4 to the m-stage shift register of the signal comparator. The shift amount d1 at the point where the S value of graph C4-6) obtained by processing by the so-called first processing means similar to that described in detail in the explanation of the focus detection processing means of the apparatus becomes zero is approximately - Detecting that Q, 3, and then
As shown in FIG. 6, the graph of FIG. 4 [4-1]
The first of a pair of photoelectric element groups (A1 to An, Bj to Bn) that captures the image patterns α and b of the graph [6-1] that are the same as
A subdivision consisting of a plurality of photoelectric elements centered on the photoelectric element where the difference between adjacent output signal values of at least one of the output signals and the second output signal is the largest; in the case of this embodiment, photoelectric element A6 and The difference between the output signals of A7 is 20 (=48-2
8) and is the largest, with A4 centered around the photoelectric elements A6 and A7.
The output signals of the other photoelectric element group (B1 to B) on the b side are plotted as a graph (
The graphs r6-2-2) and Cb 2 3) illustrate each state when shifted one shift left or right based on b-zi), but in reality, it is further shifted left or right by one shift. , the photoelectric elements A4~ in each state at that time.
The output signals of each photoelectric element facing A9 are inputted to the m-stage shift register as appropriate, and processed by equation (1) or equation (2) used in the processing of FIG. 4, resulting in graph C63]. By finding the S value supremacy and selecting the shift amount d2+0.1 that makes the S value zero at this time,
The signal comparator outputs the shift amount d1 key 0.6 in the first processing means as the first and second shift amounts, respectively. Then, when the two first and second shift amounts output by the signal comparator are input to a selector into which a preset reference amount, for example, a reference amount of ±0.5 is input, the selection The device first compares the first shift amount and the reference amount, determines whether or not the first shift amount is within the reference range, and normally outputs the first shift amount with priority. By making the determination so that the second shift amount is output instead of the first shift amount only when the first shift amount is within the reference amount range, in this case, the first shift amount d
Since the 1 key 0°3 is within the reference amount range -0.5 to +0.5, the second shift amount d2: +0.1 is output.

Therefore, the shift amount output from the selector, in this case the shift amount d2ki0.1, is determined in advance and one shift is equivalent to 2In/B, so the defocus amount δ is +0, 2 m1m.
(*+0. I
), the defocus amount δ110.21
]1/InK It drives and controls the electric motor M by an amount corresponding to It is possible to reduce fluctuations in focus. In the subsequent focus control, when the state of the graph [5-1] in Fig. 5, which captures the subject image in which only the background of the main subject in Fig. 4 has changed, is subjected to focus control, the signal comparator first performs the first processing as described above. Graph [5
0.3 in the shift amount d1 is used as the first shift amount for which the S value in [7-7] becomes zero, and the S value supremacy corresponding to graph [7-5] is determined by the second process, and the graph [7
-s), a straight line passing through the two points is actually found and a well-known calculation is performed to find the shift amount d2''-
By capturing 7Q, 1 as the second shift amount, it is output together with the shift amount a+=0.3, and both outputs are processed by a selector to which the reference amount ±0.5 is input in advance. , In this state as well, the second shift amount is selected and output in the same manner as described above, and the output signal is from -0,1 in the shift amount d2 to -0,2 m/m (in the middle) in the defocus amount δ at that time. -0y1X 2 m/m
), and in the case of the conventional device, the defocus amount δ is 0.6 (Takashi'0.3X 2 m/m), but the defocus amount δ is 0.2In/I.
It controls the drive of the electric motor M by an amount corresponding to 11,
It is possible to suppress the variation in the amount of extension of the focusing ring of the photographing lens to approximately 1/3 of that of conventional automatic focus control devices.

1. Fig. 8 is a schematic diagram of the device of the present invention, mainly showing the focus detecting section for moving the focus ring of the photographic lens to the in-focus position.The output signals captured by the individual photoelectric elements of the light receiving array D are The output signal given to the transmitter T is applied to the cable 5, R4 through the cable KO, and the output signal is applied to the cable 5, R4. The same signal is transferred to each shift register R1, R2 of the signal comparator U via the signal comparator U and stored therein. When the clock output signal of the main clock Q1%Q2 is applied to the clock phase sequencers Jl and J2 through the cables 5 and R6, respectively, the clock phase sequencers J1 and J2 send the clock phase pulses to the cables 7 and 7, respectively. The four signals An, An41 and Bn are respectively applied to the shift registers R1 and R2 of the signal comparator U through K8.

Bn41 to cable 9, Klo z K++,
K12 s 6 S An-1-11'Ins 'dn
+1 to cable +3s IG4% KH5s K
In the case of, for example, 10 pairs of photoelectric elements as in the above-mentioned embodiment, the output signals A+ to A9, A2-A+o, B+~B9,
It continues as one cycle until Bz~B+o is transferred, while 13, K14, K15, K16 are transferred to the cable.
In the case of Fig. 6, A5~A6% A4++A7, Bj~
B9, B2+-BIO, or A2+ in the case of Figure 7
++A6. A5ゞAhaB+ 'B9. The cycle continues until the output signal of the B2NB sum is transferred as one cycle. Then, one of the four signals outputted relatively at each time is An, An++, Bn%Bn41
is the first algorithm processor P1 which performs the first processing of the signal comparator U, and the other A'n%In-Hl
nn and E/n4+ are respectively transferred to the second algorithm processor P2 that performs the second processing and are processed as described above (
2), the signal comparator U converts the signal of the first shift amount of the first algorithm processor P1 and the signal of the second algorithm processor P
Two second shift amount signals are respectively output. Furthermore,
Both the first shift amount signal and the second shift amount signal of the signal comparator U are connected to the selector ■ to which a preset reference amount is inputted to the cable via the cable 17 and K18, respectively. , the selector V first compares the first shift amount transferred from 17 to the cable with the reference amount, and only when the first shift amount is within the reference amount range, the selector V selects +a from the cable. Based on the sign of the shift amount selected and output by the selector (2) which outputs the second shift amount to be transferred, the direction in which the focus ring Lm of the photographic lens Lo for focusing is to be moved is determined, and the The drive is determined by detecting the defocus amount according to the value of the absolute amount, and the drive of the electric motor M is controlled by the signal operator, and the focus ring Lm of the photographic lens Lo is automatically moved in the direction of the arrow to the in-focus position. This is to control the output focus. Then, when all the above processes are completed, the final count signal from the counter (, +, 02) is inputted to the transmitter T via the cable 1% to 2, and is sent to each photoelectric element of the photodetector array D again. The detection operation is repeated to process new output signals.

Moreover, each algorithm processor P of the signal comparator U
The first shift amount and the second shift amount to be detected by the clock phase sequencers J+ and J2 are calculated by counting the clock signal pulses of the clock phase sequencers J+ and J2 through the cables 25 and K26 with the counters C1 and 02, respectively. It is sensed by inputting the counts to each algorithm processor P1% P2.

In the same way, the second algorithm processor tP2 detects in advance a location where the difference between adjacent output signal values of at least one of the first and second output signals is the largest, and generates a plurality of photoelectric elements centered around the photoelectric element at the location. It is programmed to capture and compare small sections of photoelectric elements.

As described above, the automatic focus control device of the present invention processes and compares all the output signals that are constantly captured by the light receiving array, detects the defocus amount, and performs focus control as in the case of conventional devices. In the subject image captured by the light-receiving array, distance measurement is possible for a sub-section centered on a location where the difference in output signal value between adjacent photoelectric elements is large, that is, a location with the greatest contrast difference, and the focus of the sub-section is determined. Since focus control is performed in consideration of the state, once focus control is performed within the reference amount range, as explained in the previous embodiment, the focus control means is switched so that changes in the background are not easily affected. This has the excellent effect of dramatically reducing image shake and stabilizing the image.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining the optical principle related to the present invention, and FIGS. 4 and 5 are graphs for explaining the first processing means related to the conventional apparatus and the apparatus of the present invention. 6 and 7 are graphs for explaining the second processing means according to the present invention, and FIG. 8 is a diagram showing an embodiment of the apparatus of the present invention. In the figure, Lo: Photographing lens, Lm: Focus ring, Lf: Small lens, D: Light receiving array, A, B,
...Photoelectric element, T...Transfer, U...Signal comparator,
R...Shift register, P...Algorithm processor, K...Reference amount, ■...Selector 12M...
·Electric motor. Figure 6 Figure 7 7-t 7-2-2 7-*-1Bn・/
234567B? ””'P' 6. Lm34
5 & 78 Bn, 2345 C7-Cho--T- 6-2-36-86・-4 7-2-37-37-4 -Tatami 1□-1

Claims (1)

[Claims] The imaging effect light ray of the photographing lens (Lo) is divided into pupils and captured by a pair of photoelectric element groups (A1 to Ans Bj to Bn), and the first of the pair of photoelectric element groups (Al to An, B+ to Bn)
In the automatic focus control device, the focus of the photographing lens (LO) is controlled by an electric motor (M) according to the defocus amount obtained by comparing the second output signal with the pair of photoelectric element groups (A1 to An1B1). ~Bn), and the gradient value of at least one of the opposing first and second output signals in each shifted state, and its location. The value of the difference between the first degree of the second output signal and the second output signal is multiplied by the first shift amount such that the total sum (S) of the combined values is zero, and the pair of photoelectric element groups (A1 to An1B+ ~ Bn) of at least one of the first and second output signals, the photoelectric element having the largest difference between the adjacent output signal values is the center of the subdivision consisting of a plurality of photoelectric elements. Shifts the output signal relative to the other output signal, and in each shifted state, the opposite first
and the slope value of at least one of the second output signals and the difference value between the first and second output signals at that location. a signal comparator (U) that outputs the amount as a second shift amount;
The first and second shift amounts of the signal comparator (U) and a preset reference amount are input, and the second shift is performed only when the first shift amount is within the reference amount range. a selector (V) that outputs one of the first and second shift amounts, and a defocus amount that is set by the shift amount output by the selector (V); An automatic focus control device 0 characterized in that it has a controller (G) that drives and controls the electric motor (M) using a drive signal (T,).