JP2002357765A - Focus detector of camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detector of a camera which detects a correct focus by carrying out optimum integral control. SOLUTION: The focus detector of the camera is provided with a focus detecting part 3 to detect the focus of a photographic lens by using a photoelectric converting element, a first and second integral control parts 1a and 1b to control the charge storage of the photoelectric converting element of the focus detecting part 3, and further provided with an integral control switching part 1c which performs selective switching so as to activate the first integral control part 1a when a control means (microcomputer) to manage the control of the entire camera including a focus control part 1d also performs control other than focus detection control, for example, when a first RSW(release switch) is OFF and so as to activate the second integral control part 1b when the control means controls only the focus detection, for example, when the first RSW is ON. Thus, the focus detection is more correctly performed by the optimum integral control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a focus detection device for a camera which measures a distance by performing integral control.

[0002]

2. Description of the Related Art As a technique relating to a focus detection device in recent years, there is, for example, Japanese Patent Application Laid-Open No. 7-98428 (known as a known example). This is a camera technology using a photoelectric conversion element that accumulates electric charge according to the amount of light reflected from a subject as a sensor. As shown in the graph of FIG. 13A, the progress of the integration process for focus detection The integration level of MDATA is monitored in a time-series manner by the AF sensor, and the slope (change rate) of the graph is calculated from the monitor value obtained by AD-converting the monitor signal at two points in the initial stage. This is to predict an appropriate integration end time that will reach the end level, and it can be said that this is an integration control method in which integration is stopped after the predicted integration time has elapsed. According to this method, if the monitor value is accurate, theoretically, FIG.
The proper integration as shown in (b) is obtained.

Further, US Pat. No. 4,410,261 (referred to as a known example) discloses a method of performing integral control based on an integral monitor output continuously sampled and outputted from an AF sensor. This is an integration control method in which a changing monitor signal is always detected by an AF sensor until a proper integration end level is reached.

[0004] Conventionally, many autofocus cameras capable of measuring a distance by using any of such techniques have been provided.

[0005]

However, the above-mentioned 2)
The two methods have the following disadvantages in addition to the advantages. That is, the technique taught in the above-mentioned known example is based on the first release switch (1R) of the release switch.
SW) is suitable for AF processing during the OFF state, but integration is stopped after the predicted time elapses.
If there is any error in the monitoring result, the integration amount subjected to the integration process always varies.

Normally, in actual integration processing, FIG.
As shown in the graph curve of (a), an unstable MDATA graph due to the incorporation of noise or the like at the time of monitoring is easily obtained, and an error occurs in prediction using the graph. There is a problem that the result of over-integration or under-integration as shown in FIGS. 14B and 14C is obtained from the incorrect monitor prediction.

On the other hand, the technique taught in the above-mentioned known example is as follows.
This is a method suitable for AF processing after 1RSW is turned on. However, this method has a drawback that it is difficult for the CPU to perform other processing during the integration processing because the sampled monitor output must always be subjected to AD conversion processing.

As described above, although the variation in integration is large in the method of the known example, since the CPU can perform other processing during integration, it is suitable for distance measurement (constant distance measurement) during the 1RSW OFF state. The method has the opposite effect, and is suitable for distance measurement after the 1RSW ON operation. Therefore, each of these known examples having advantages and disadvantages or each of the methods of the known examples alone cannot always be said to be a camera which can always provide optimal integration control. .

Therefore, in response to a request from a user to improve the accuracy of a camera, more accurate focus detection is required, and the optimum integral control is required. SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and a purpose thereof is to provide a camera focus detection device capable of performing more accurate focus detection by performing optimal integration control regardless of the release operation state of the camera. Is to provide.

[0010]

Means for Solving the Problems In order to solve the above problems and achieve the object, the present invention takes the following measures. That is, according to the first aspect, control means (CPU) for controlling the entire camera, focus detection means (focus detection unit) for detecting the focus of the photographing lens using a predetermined photoelectric conversion element,
First integration control means (first integration control unit) for controlling the charge accumulation of the photoelectric conversion element of the focus detection means, and charge accumulation control for the charge accumulation control of the photoelectric conversion element of the focus detection means. Second integration control means (second integration control unit);
When the control means is also performing control other than focus detection control (when 1RSW is OFF), the first integration control means is operated, and when the control means is performing only focus detection control (when 1RSW is OFF). The present invention proposes a camera focus detection device including an integral control switching unit (integral control switching unit) for selectively switching the second integral control unit to operate (when ON).

The above-mentioned control means comprises a microcomputer, and the first integration control means stops the integration by using an interruption process of the microcomputer. I do.
Further, in a camera having a release switch (1RSW, 2RSW) composed of a two-stage switch for exposing the camera, the first integration control means operates when the release switch is not pressed (when the 1RSW is OFF). The second integration control means operates when the release switch is pressed (when the 1RSW is turned on), and proposes the focus detection apparatus according to the first invention, wherein

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A camera focus detection apparatus according to the present invention utilizes the advantages of each of a plurality of types of conventional systems and performs their optimal application in order to perform more accurate and optimal integration control. It is something devised. The camera exemplified here is based on an AF camera having a release switch including a two-stage switch (1RSW and 2RSW) via a release button for an instruction operation for performing an exposure operation from photometry and distance measurement. ing.

An outline of the main features of the present invention is that two integration control systems are selectively applied by paying attention to the timing of a release operation. 1RSW is OFF), the CPU needs to perform other processing even during the AF processing.
The processing load on the PU is large, and during this period, control is performed so as to perform integration by applying a well-known integration control method while going around the main loop of the control program. 1RSW is O
When the N operation is performed, the CPU does not need to perform other processing during the AF processing, so that the CPU can start the processing for integration control. In other words, it can be said that the integral control method of the known example is applied here to prevent the integration result from being excessive or insufficient.

Hereinafter, the present invention will be described in detail with reference to specific embodiments. First, FIG. 1 shows a functional block diagram of a camera system according to an embodiment of the present invention, in particular, features of the configuration of a focus detection device. This camera is
The camera has a control means composed of a microcomputer for controlling the entire camera. The focus detection device of the camera is a focus detection means (focus detection unit 3) for detecting the focus of the taking lens using a predetermined photoelectric conversion element. To the focus control unit 1d
Has the base of control. Switching control between first integration control means (first integration control section 1a) and second integration control means (second integration control section 1b) for performing charge accumulation control of the photoelectric conversion element of the focus detection means. Have it possible.

An integral control switching means (integrator) for selectively switching the first integral control unit 1a or the second integral control unit 1b to operate selectively based on the release operation status of the camera (for example, ON / OFF of 1RSW). Control switching unit 1
c) is further provided. That is, when the control unit including the focus control unit 1d is also performing control other than focus detection control (that is, when the 1RSW is turned off).
), The first integration control means is operated, and when the control means is performing only the focus detection control (that is,
This is a camera focus detection device provided with an integral control switching means (integral control switching unit 1c) for selectively switching between these integral controls so as to activate the second integral control means when the 1RSW is ON.

In addition, using the value obtained by the integration,
It has a focus control unit 1d that performs optimal focus control for focusing on the subject. The first integration control section 1a can stop the integration by using the interruption processing of the microcomputer. The first integral control section 1a operates when the release switch is not pressed (when the 1RSW is turned off), and the second integral control means operates when the release switch is pressed (1RS).
(When W is ON).

In other words, the focus detection device selects and switches the first integration control unit 1a and the second integration control unit 1b for the integration control of the focus detection in accordance with the timing that can be optimally applied. Since the switching unit 1c is provided, regardless of the release operation status at that time,
Appropriate control is performed so that optimal integration control can be performed.

The focus detecting device of the camera exemplified in this embodiment is a part of a camera having a camera optical system as shown in FIG. Here, the configuration will be described focusing on an optical system related to focus detection of a camera system having a built-in zoom lens mechanism. This camera includes, for example, a photographing lens 11 including five lens groups 11a to 11e and a photographing aperture 31, a main mirror 12 that rises during photographing,
It mainly includes a finder optical system 13 for checking a photographing screen and the like, an AF optical system 15 for performing automatic focus adjustment (AF), and a shutter 28 arranged in front of the film 29.

The photographing lens 11 includes a first lens group 11a and a second lens group 11b for performing focusing.
And a third lens group 11c and a fourth lens group for performing zooming.
And a fifth lens group 11e comprising a fixed lens. When zooming with the taking lens 11, the third lens group 11c and the fourth lens group 11d are driven,
The first lens group 11a and the second lens group 11b are driven by a cam structure (not shown) to perform a zooming operation and prevent a focus shift.

The AF optical system 15 includes a field stop 1
6, infrared cut filter 17, condenser lens 18,
It comprises a mirror 19, a re-imaging stop 20, a re-imaging lens 21, and an AFIC 22, which will be described in detail later. The field stop 16 determines the field of view for AF detection from the shooting screen, and is provided so that the two light images split by the re-imaging lens 21 do not interfere with each other. The infrared cut filter 17 is provided to remove infrared light unnecessary for AF detection and prevent aberration shift due to the infrared light. The condenser lens 18 is provided in the vicinity of the image plane of the subject light image formed by the photographing lens 11, that is, in the vicinity of the film equivalent plane, and re-images the subject light image formed in the vicinity of the film equivalent plane together with the re-imaging lens 21 on the AFIC 22. It is to make it. The re-imaging stop 20 is symmetrical with respect to the optical axis and forms a pair, so that the two light beams passing through the condenser lens 18 are re-imaged on the two photoelectric conversion element arrays on the AFIC 22. Has become.

The finder optical system 13 includes a focusing screen 23, a condenser lens 24, a prism 25, a mold roof mirror 26, an eyepiece 27, and a photometric sensor 30. The main mirror 12 has a half-mirror structure, and a sub-mirror 14 is attached below the main mirror. When the film is exposed, it retreats to the position indicated by the dotted line in the figure (corresponding to the direction of arrow G6 in the figure).

When photographing is performed by the camera of the present embodiment configured as described above, the reflected light A from the subject is
As shown by an arrow in the drawing, the light is first incident on the main mirror 12 via the photographing lens 11. In the main mirror 12, two-thirds of the incident light amount is reflected toward the finder optical system 13, and the remaining one-third of the incident light amount passes through the main mirror 12, is reflected by the sub mirror 14, and is guided to the AF optical system 15. I will In the AF optical system 15, the subject light beam A removes unnecessary infrared light with a field stop 16 and an infrared cut filter 17, passes through a condenser lens 18, is reflected by a mirror 19, and is recombined. The subject light image formed near the film equivalent plane is re-formed on the AFIC 22 via the image stop 20 and the re-imaging lens 21.

In the finder optical system 13,
The light image of the object passing through the photographing lens 11 is formed on a focusing screen 23, and the formed image is guided through a condenser lens 24 and an eyepiece 27 so that the photographer can observe the photographing screen. At the time of photographing, the main mirror 12 and the sub-mirror 14 are retracted in the direction of arrow G6, and the subject light image passing through the photographing lens 11 is exposed on the film 29 through the opening of the shutter 28.

Referring more specifically to FIGS. 3 and 4,
The above-described camera will be described. FIG. 3 shows the configuration of the entire camera system including the focus detection device of the camera. This camera system includes a CPU 1 as a camera control unit, a remote control receiving circuit 2, a focus detection unit 3
A focus detection circuit 3a, a focus adjustment lens drive circuit 4, a zoom drive circuit 5, an aperture drive circuit 6,
Strobe circuit 7, film drive circuit 8, shutter drive circuit 9, photographing lens 11, photometric circuit (AE) 30
And various switch groups 5 such as 1RSW and 2RSW, for example.
0.

FIG. 4 shows an AF sensor (AF) shown in FIG.
3 shows a detailed configuration of the IC 22). This AFIC2
Reference numeral 2 denotes a pair of left and right photosensor arrays 36R and 36L, an amplifier circuit 60 for amplifying the output of each sensor, and a shift register 6 for shifting the amplified signal.
1 and a terminal MD as a monitor signal based on these signals.
It comprises a monitor output circuit 62 for outputting from the ATA and a control circuit 63 for controlling the entire AF sensor.

In such a sensor configuration, electric charges generated in response to light incident on the left and right photosensor arrays 36R and 36L are stored in a storage capacitor in the amplifier circuit 60 for each photosensor (pixel). Amplified. Then, each pixel signal amplified in the amplifier circuit 60 is converted by the monitor output circuit 62 into a signal corresponding to the maximum value of all pixels, and is output from the terminal MDATA to the AD converter of the CPU 1. This terminal MDATA
Is a signal indicating the accumulation level of the electric charge stored in the storage capacitor.

On the other hand, each pixel signal amplified by the amplifier circuit 60 is supplied to the terminal SD in synchronization with the clock signal of the terminal CLK output from the CPU 1 by the shift register 61.
The data is sequentially output from the ATA.
Input to the D converter. The control circuit 63 includes the CPU 1
To control the operation of each block in the AFIC 22. The reference voltage V _REF is input to the amplifier circuit 60 from an interface IC (not shown), and serves as a reference potential inside the amplifier circuit 60.

FIG. 5 is a time chart showing changes in various signals input / output at each terminal shown in FIG. When the CPU 1 outputs the L (Low) level RESET signal, the blocks inside the AFIC 22 are initialized, and the accumulation operation starts in synchronization with the H (High) level RESET signal. As described above, the signal indicating the accumulation level is output to the terminal MDATA. Line segments a and b in the figure show the change of the MDATA signal at the time of light and dark depending on the magnitude of the incident light amount, and the line segment a relatively represents the large incident light amount and the line segment b relatively represents the small incident light amount.

In the CPU 1, after the accumulation is started, the MDATA signal is AD-converted by the AD converter to monitor the accumulation level. As shown in the figure, the smaller the value of the MDATA signal is, the larger the charge storage amount of each pixel is.
Then, when the storage amount becomes appropriate, the CPU 1
The signal is changed from H level to L level, and the accumulation operation is stopped. The CPU 1 calculates the accumulated time, that is, R
When the ESET signal changes from L level to H level, EN
The time required for the D signal to change from H level to L level is counted by an internal counter and stored as an integration time.

Next, the CPU 1 outputs a clock for reading a pixel signal to the terminal CLK. The pixel signal is sequentially transmitted to the terminal SDATA in synchronization with the clock of the terminal CLK.
The CPU 1 converts the SDATA signal from analog to digital and stores it as pixel data in a predetermined internal storage area.

Next, the operation of the camera system according to the present embodiment will be described with reference to the flowcharts shown in FIGS. 6, 7, and 9 to 12. FIG. 6 is a main routine showing the operation procedure of the camera system in a flowchart. First, when a main switch (not shown) of the camera is turned on by a photographer's operation, the CPU 1 is powered on and reset to start operation, and initialization of an I / O port and initialization of a RAM are performed. (S1). In the following step S2, based on the output from the AFIC 22,
The predetermined calculation for AF is performed in a subroutine “AF
"1" is called (S2).

The release switch is 1RSW, 2RS
Since it is a two-stage switch structure consisting of W, half-pressing it to 1RS
When W is turned on, AF and lens driving are started, and when fully pressed, 2RSW is turned on to perform an exposure operation. Therefore, in the next step S3, it is determined whether or not 1RSW is on (S3).
As other processing, for example, after processing other than distance measurement or waiting for a predetermined period, the process returns to step S2 again. Meanwhile, 1
When the RSW is turned on, after performing the photometry processing (S8),
Based on the output of the AFIC 22, the calculation necessary for AF is
This is performed by calling a subroutine "AF2" described later (S
9). However, this is an AF process for calculating a drive amount for driving the lens, which is different from “AF1” when the 1RSW in step S2 is off (details will be described later).

After driving the lens (S1)
0), it is determined whether the taking lens 11 is in focus (S)
11). Here, the photographing lens 11 is driven by driving the lens.
Is determined to have been driven to the in-focus position. If the photographing lens is not focused on the subject, the process returns to step S2, and the calculation is repeatedly performed until the focusing is achieved in step S10. However, if the focus is achieved, it is determined in step S12 whether or not the 2RSW is on (S12).

If it is determined that the 2RSW is off, the process returns to step S2. If the 2RSW is on, the following processes are sequentially executed from step S13 to step S19. First, the diaphragm is driven to the calculated value (S13), and the main mirror 12 is raised (S1).
4). Then, the shutter 28 is controlled to open for the calculated opening time (S15). When the shutter 28 opens for a predetermined time, the main mirror 12 is lowered (S1).
6), the aperture is set to open (S17), and the shutter 28
Is charged to the initial position (S18), and one frame is wound up (S19). Thereafter, the process returns to step S2, and the same processing steps as described above are repeated.

In the flowchart of FIG.
A subroutine processing procedure relating to automatic focus adjustment (AF1) of FIG. First, a predetermined integral control is performed by calling "integral control 1" described later (S20). Thereafter, it is determined whether or not to shift to the operation (S21). If not, this routine is terminated and the routine returns.

When the operation proceeds to the calculation, first, the sensor data S
Data is read (S22). Then, based on output signals from the pair of left and right photo sensors, a predetermined correlation operation of a well-known technique is performed to obtain a deviation (S23). Here, it is determined whether or not the subject can be correctly detected (S2).
4) If there is no contrast and detection is not possible,
The detectable flag is cleared (S26), and the routine returns. If detectable, the detectable flag is set first (S25), and the defocus amount is calculated (S27). Then, the lens drive amount is calculated (S28), and the process returns.

Here, the integration process performed by the camera focus detection device of the present embodiment will be described. FIG. 8 is a graph showing the degree of integration progress from the start of monitoring for the two types of integration control in a time-series manner. Show. First integral control section 1a
Calculates the change (ΔV: slope of the graph) of the monitor value per unit time (ΔT) based on the first and second monitor signals shown in the figure. Then, it is possible to predict and calculate a time until the monitor value of MDATA indicating the degree of integration progress output from the AF sensor 22 reaches a predetermined threshold (threshold) at which integration can be completed. For example, if a sufficiently bright light amount is obtained from the subject, the AF sensor can achieve the charge accumulation that can complete the integration in a short time, so that the prediction time is shortened.

This control, which is performed only in the initial stage, can extremely shorten the processing time occupied by the CPU 1 and minimize the load on the CPU 1. On the other hand, the second integration control unit 1
As for b, by observing the monitor signal from the first time to the n-th time, it is possible to know the timing when the monitor value of MDATA reaches a predetermined threshold value accurately and comparatively. Therefore, if this operation is performed at a time when the load on the CPU 1 is small, an extremely accurate result can be obtained.

Therefore, in the present embodiment, the integration control switching section 1c controls the integration control by either the first integration control section 1a or the second integration control section 1b while observing the state of 1RSW. Switching is performed so that each integral control unit is controlled to operate at a time when it is good at (ie, optimal application timing).

Next, the processing procedure of the above-described subroutine "integration control 1" will be described with reference to the flowchart of FIG. First, it is determined whether or not integration is continuing (S20a). If not, the process proceeds to step S20b described below. If integration is continuing, it is determined whether or not a timer interrupt has been set (S20c). If not, AD conversion of the monitor value is performed (S20b), and the routine goes to step S20i. On the other hand, if it has been set, the process returns.

In step S20b, first, the AF sensor is reset (S20b). Also, a flag indicating that the integration is continuing is set (S20e), and the monitor value AD is set.
Conversion is performed (S20f). Then, the process waits for several tens μsec. (S20g), and then performs AD conversion of the monitor value (S20h).

In step S20i, it is determined whether a predetermined maximum allowable time (for example, 200 to 300 msec) has elapsed (S20i), and if it has elapsed, the integration time is set to a predetermined maximum value (S20k). ), Step S20 described later.
Move to S. On the other hand, if it has not elapsed yet, it is determined whether or not the monitor value has already been integrated (S20).
j) If completed, the process proceeds to step S20S described later.

If the integration has not been completed, it is determined whether or not time prediction is possible (S201). If possible, the process proceeds to step S20Q described below. On the other hand, in the case of no, first, a standby of several msec. Is performed (S20m),
The monitor value is AD-converted (S20n). And where
It is determined whether or not the integration has already been completed (S20O). If the integration has been completed, the process proceeds to step S20S described later. If not, it is determined whether or not time prediction can be performed (S20P). If possible, the integration time is predicted in step S20Q (S20Q).
20Q), set a timer interrupt (S20R), and return. In step S20S, the integration is stopped irrespective of the interruption (S20S), and a flag for shifting to the calculation is set (S20T). And return.

The flowchart of FIG. 10 shows the processing procedure of a subroutine relating to integration stop using a timer interrupt. When the time predicted in S20Q elapses, the process branches off here to stop integration. First, integration stop is performed by operating a preset timer interrupt function (S3).
0), the integration time is set (S31). Further, a flag for shifting to the operation is set (S32), and the interrupt is released (S33). And return.

The flowchart of FIG. 11 shows the processing procedure of a subroutine relating to the second automatic focus adjustment (AF2). Here, first, it is determined whether or not the result of the above-mentioned “AF1” can be used in terms of reliability (S90). In this determination, for example, when there is no difference in the magnitude of contrast, or when there is no difference between AF1 and AF2. If the temporal timings are far apart, it is determined that the result of the previous AF1 is unreliable, and the AF is executed again here. If there is reliability and the result of AF1 can be used, the process directly returns. On the other hand, if it cannot be used, “integration control 2” described later
To perform predetermined integral control (S91).

The sensor data SDATA is read (S92), and a predetermined correlation operation is similarly performed (S92).
93). Here, it is determined whether or not the detection is correct (S94). If the detection is not possible, the detectable flag is cleared (S95) and the process returns. If detectable, a detectable flag is set (S96), and the defocus amount is calculated (S97). Then, the lens driving amount is calculated (S98). And return.

The flowchart of FIG. 12 shows the processing procedure of the above-described subroutine "integration control 2". First, the AF sensor is reset (S91a). In step S91b, AD conversion of the monitor value is performed (S91).
b).

Then, it is determined whether or not the monitor value has already been integrated (S91c). If the integration has been completed, the process proceeds to step S91f described later. If the integration has not been completed, the process proceeds to step S91d. In the same manner as described above, it is determined whether or not the predetermined maximum allowable time has elapsed (S91d). If not, the process returns to step S91b. If it has elapsed, the integration time is set to the predetermined maximum value. Yes (S91
e). In step S91f, the integration is stopped without interruption (S91f), and the integration time is set (S91f).
g) Return.

As described above, according to the present embodiment, based on the timing of the release operation, control is performed so that the two types of integration control methods can be optimally applied while being selectively switched by the integration control switching means so that the integration processing can be performed. ing. Whether to emphasize the accuracy of integration or the processing time by the CPU is determined by C
In consideration of the processing load of the PU and the necessity of other processing that must be performed, the integration control method can be switched at an appropriate timing, so that the distance measurement can always be performed with an appropriate integration result according to a shooting situation. it can. In addition, by creating a control program that switches the integration control method at an appropriate timing without changing the hardware structure of the camera itself, a more accurate focus detection device for the camera can be realized.
It can be realized relatively easily.

(Modification) The first embodiment described above may be modified as follows. For example, as shown in FIG.
The integral control unit 1a, the second integral control unit 1b, the integral control switching unit 1c, and the like mainly execute the parts related to control by software (control program), and if possible, by hardware. Good.

The predetermined values, such as the threshold value and the time value, relating to each control are not limited to the exemplified values but can be changed as appropriate as long as the integration processing accuracy is improved. By these modified embodiments, the same or higher effects as those of the illustrated embodiment can be expected. In addition, various modifications can be made without departing from the spirit of the present invention.

Although the embodiments have been described above, the present invention includes the following inventions. (1) The focus detection means outputs a monitor signal indicating a degree of integration progress, and the second integration control means stops integration by constantly observing the monitor signal. The focus detection device of the camera described above can be provided.

(2) The apparatus further comprises prediction means for predicting an integration time from the start of integration to the end of integration, wherein integration is stopped using interrupt processing based on the prediction time of the prediction means. 2. A camera focus detection device according to item 2. (3) When the 1RSW of the release switch is in the OFF state, the distance measurement that emphasizes the processing by the CPU and the 1RSW
4. The focus detection device for a camera according to claim 3, wherein the integral control method is switched in the distance measurement in which importance is attached to the integration accuracy when W is ON.

(4) The focus detection of the camera according to claim 1, wherein the first integration control means controls so as to monitor the progress of integration at two points in an initial stage of the integration processing. Equipment can be provided. (5) The second integration control means controls to monitor the progress of integration over the entire period from the start to the end of the integration process.
Can be provided.

[0055]

As described above, according to the present invention, the release operation status of the camera (for example, 1RSW ON / OF)
By performing optimal integration control irrespective of F state), it is possible to provide a camera focus detection device capable of performing more accurate focus detection than before.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a camera focus detection device according to the present invention.

FIG. 2 is a configuration diagram showing a configuration of an optical system related to focus detection of the camera.

FIG. 3 is a block diagram showing the overall configuration of a camera system including the focus detection device.

FIG. 4 is a configuration diagram showing a detailed configuration of an AF sensor (AFIC) shown in FIG. 2;

FIG. 5 is a time chart showing waveform changes of input / output signals from each terminal of the AF sensor shown in FIG. 4;

FIG. 6 is a flowchart as a main routine showing an operation procedure of the camera system according to the embodiment.

FIG. 7 is a flowchart illustrating a processing procedure of a subroutine relating to automatic focus adjustment (AF1).

FIG. 8 is a graph showing a time-series relationship between the integration process and the number of times of monitoring.

FIG. 9 is a flowchart illustrating a processing procedure of a subroutine relating to first integration control (integration control 1).

FIG. 10 is a flowchart illustrating a processing procedure of a subroutine related to stopping a timer interrupt integration.

FIG. 11 is a flowchart illustrating a processing procedure of a subroutine relating to automatic focus adjustment (AF2).

FIG. 12 is a flowchart illustrating a processing procedure of a subroutine relating to second integration control (integration control 2).

13 (a) and 13 (b) show a time change graph of the degree of integration progress and a graph showing the output of all pixels as the integration result, and FIG. 13 (a) shows the integration progress based on the AF sensor output signal. A graph showing the relationship between the degree of integration and the integration time, and (b) is a graph showing the integration result.

14A to 14C show a conventional actual integration process in integration control, and FIG. 14A is a graph showing an integration process based on a signal when there is a lot of noise;
(B) and (c) are graphs showing over integration and under integration.

[Explanation of symbols]

1. Control means (microcomputer: CPU), 1a
1st integration control section (first integration control means), 1b second integration control section (second integration control means), 1c integration control switching section (integration control switching means), 1d focus control section (focus control) Means), 2 ... remote control receiving circuit, 3 ... focus detection unit, 3
a: focus detection circuit, 4: focus adjustment lens drive circuit, 5 ...
Zoom drive circuit, 6 ... Aperture drive circuit, 7 ... Strobe circuit, 8 ... Film drive circuit, 9 ... Shutter drive circuit, 1
REFERENCE SIGNS LIST 1 photographing lens 12 main mirror 13 finder optical system 14 sub-mirror 15 AF optical system 22 AF sensor 30 photometric circuit 36R
36L: Photosensor array, 50: Various switch groups (1RSW, 2RSW, etc.). 60 ... amplifying circuit, 6
1: shift register, 62: monitor output circuit, 63: control circuit (AF sensor control unit) S1 to S19: Main routine processing steps, S20 to S28: AF1 processing steps, S20a to S20T: Integration control processing steps during AF1, S30 to S33: Timer interrupt processing steps, S90 to S98: AF2 processing steps , S9
1a to S91g... Processing steps of integration control during AF2.

Claims (3)

[Claims] A control means for controlling the entire camera; a focus detection means for detecting a focus of a photographic lens using a predetermined photoelectric conversion element; and a predetermined charge accumulation control for the photoelectric conversion element of the focus detection means. First integration control means for performing a predetermined charge accumulation control of the photoelectric conversion element of the focus detection means, and when the control means also performs control other than focus detection control. The first integration control means is operated at the same time, and the second integration control means controls only the focus detection control.
A focus detection device for a camera, comprising: integration control switching means for selectively switching so as to activate the integration control means. 2. The focus detection of a camera according to claim 1, wherein said control means comprises a microcomputer, and said first integration control means stops integration by using an interruption process of said microcomputer. apparatus. A release switch comprising a two-stage switch for causing the camera to perform exposure, wherein the first integral control means operates when the release switch is not pressed, and the second integral control means 2. The camera focus detecting device according to claim 1, wherein the device operates when the release switch is pressed.