JPH03212605A - Focus detector - Google Patents

Abstract

PURPOSE:To enable a photographer to be informed of the focus states in respective regions by detecting the defocusing quantities of plural different subject regions, displaying the defocusing quantities in correspondence to the subject regions and simultaneously displaying the region within the specified threshold of the defocusing difference as well. CONSTITUTION:The image information on the plural different subject regions is inputted onto the respective sensors of a sensor SNS in a mode for selecting the visual field for distance measurement and thereafter, prescribed focus detection computation is executed by a microcomputer and the defocusing quantities are respectively independently detected. The luminous flux from a light emitting diode SPI is simultaneously introduced via a lens array LNSA and a projecting lens LNSB onto a quick return mirror QRM where the luminous flux is reflected and the visual field for distance measurement in the selected position of the display part of a focal plate FSCRN is displayed together with the subject image in a finder. The focus states of the respective regions are eventually displayed in the finder if the defocusing difference from the selected subject region is within the specified threshold.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-point focus detection device that detects the amount of defocus of a plurality of subject areas and performs focus detection.

[Conventional technology]

Conventionally, as a focus detection device for a camera, a pair of image signals obtained by photoelectrically converting the subject image is formed by focusing the light flux from the subject area that has passed through different exit pupil areas of the photographing lens on a pair of line sensors. A well-known method is to detect the amount of defocus of a subject area by determining the amount of relative positional displacement. In addition, in the above method, a focus detection system (
Many methods have also been proposed for detecting the defocus amounts of multiple object areas by preparing multiple sets of optical systems and sensors.

[Problem that the invention is trying to solve]

If the amount of defocus is detected for each of the above multiple areas, distance measurement will be performed for multiple subject areas, but the focus is ultimately adjusted for the subject for one distance measurement area. In order to target the subject, the camera is provided with means for selecting a subject area from among a plurality of areas based on some determination condition, and is configured to adjust the focus on one of the subject areas.

In this case, since it is not clear which area is the selected area, it is necessary to provide display means for displaying the selected area in the finder, for example, to inform the user of the selected area, that is, the area on which the focus has been adjusted.

On the other hand, if configured as above, one area out of multiple areas will be selected and only that area will be displayed, even if there is an area that has a defocus amount close to the defocus amount in the selected area. Only one area is displayed (in other words, subjects in multiple areas show the same or almost the same amount of defocus, and if you focus on the subject in one area, you can easily take pictures of subjects in other areas. Even though the object is in focus, it is not possible to know this.Also, if the object in each area is at approximately the same distance, the focus detection operation is repeated each time the focus is detected. The displayed area changes each time, and the photographer may think that focus detection is being performed unstablely.

[Means to solve the problem]

The present invention has been made in view of the above-mentioned problems, and it is possible to display the distance measurement area corresponding to the subject area not only by displaying the distance measurement area corresponding to the selected subject area (but also by displaying the distance measurement area corresponding to the selected subject area). It is an object of the present invention to provide a display circuit for a focus detection device that solves the above-mentioned problem by simultaneously displaying that area if it is within a threshold value.

〔Example〕

FIG. 1 is a diagram showing a schematic configuration of a focus detection device employed in an automatic focus adjustment device according to the present invention.

In the figure, MSK is a visual field mask, and a cross-shaped opening MSK-1. Vertical openings MSK-2 on the periphery of both sides
, MSK-3. FLDL is a field lens and the three apertures MSK-1, MS of the field mask
Corresponding to K-2, MSK-3, three parts FLDL-
It consists of 1, FLDL-2, and FLDL-3. DP
is a diaphragm, and in the center there are a total of four openings DP-1a and DPlb, one pair each on the top, bottom, left and right.

DP-4a, DP-4b, and one pair of two openings DP-2a, DP2b, and DP-3 in the left and right peripheral areas.
a.

DP-3b is provided respectively. Each region FLDL-1, FLDL-2°FLDL-3 of the field lens FLDL has a pair of apertures DP-1, DP, respectively.
4. It has the function of forming images of DP-2 and DP3 near the exit pupil of an objective lens (not shown). AFL has 4 pairs of lenses AFL-1a, AFL-1b, AFL-4a
.

AFL-4b, AFL-2a, A
F L-2b, A F L-3a.

It is a secondary imaging lens consisting of AFL-3b, and the aperture DP
are arranged behind each opening in correspondence with each other.

SNS has 4 pairs of sensor rows 5NS-R, 5NS-C, 5N
The sensor is composed of SL and 5NS-CH, and is arranged so as to correspond to each secondary imaging lens AFL and receive its image.

In the focus detection system shown in Fig. 1, when the focal point of the photographing lens is in front of the film plane, the subject images formed on each pair of sensor rows are close to each other, and when the focal point is behind the film plane, the subject images are close to each other. In this case, the subject images are separated from each other. This amount of relative positional displacement of the subject image has a specific functional relationship with the amount of defocus of the photographing lens, so if appropriate calculations are performed on the sensor outputs of each pair of sensor rows, the amount of defocus of the photographing lens, It is possible to detect the so-called defocus amount.

By adopting the configuration described above, it is possible to measure even objects whose light intensity distribution changes only in one direction, vertically or horizontally, near the center of the range photographed or observed by an objective lens (not shown). The peripheral openings of the field mask other than the center MSK-2, MSK
It is also possible to measure the distance to an object located at a position corresponding to -3.

FIG. 2 shows the arrangement of a focus detection device having the focus detection system shown in FIG. 1 housed in a camera.

In the figure, LNS is a zoom shooting lens, QRM is a quick return mirror, FSCRN is a focus plate, PP is a pentaprism, EPL is an eyepiece, FPLN is a film surface, and S
M is a submirror, MSK is a field mask, CF is an infrared cut filter, FLDL is a field lens, RMI,
RM2 is the first. A second reflection mirror, SHMSN is a light-shielding mask, DP is an aperture, AFL is a secondary imaging lens, AFP is a prism member having a reflection surface AFP-1 and an exit surface AFP-2, and SNS is a cover glass 5NSCG and a light-receiving surface 5N.
This is a sensor with SPLN. The prism member AFP has a reflective surface AFP-1 on which a metal reflective film such as aluminum is deposited, and has the function of reflecting the light beam from the secondary imaging lens AFL and deflecting it to the exit surface AFP-2. There is. SPI is a light emitting diode, LNSA is a gradient index lens array, and LNSB is a light projection lens. light emitting diode SP
The luminous flux of I is the lens array LNSA and the light projection lens LNS.
After being reflected on the quick return mirror QRM via B, the light illuminates the display section on the focus plate FSCRN.

FIG. 3 is a circuit diagram showing an example of a specific configuration of a camera equipped with a focus detection device as shown in FIG. 1. First, the configuration of each part will be explained.

In FIG. 3, PH1 is a camera control device, which includes, for example, a CPU (central processing unit), ROM, and RAM.

It is a l-chip microcomputer (hereinafter referred to as microcomputer) that has an A/D conversion function. Microcomputer PR8 is R
A series of camera operations such as automatic exposure control function, automatic focus adjustment function, film winding and rewinding, etc. are performed according to the camera sequence program stored in the OM. For this purpose, the microcomputer PR3 uses communication signals So, SI,
5CLK, communication selection signal CLCM, C3DR, CDD
R is used to communicate with peripheral circuits within the camera body and the control device within the lens, and to control the operation of each circuit and lens.

SO is the data signal output from the microcomputer PR5, SI
is a data signal input to microcomputer PR3, and 5CLK is a synchronization clock for signals So and SI.

LCM is a lens communication buffer circuit, and when the camera is in operation, it supplies power to the lens power supply terminal VL, and the selection signal CLCM from the microcomputer PR5 is set to a high potential level (hereinafter referred to as "H", low potential level). is “L”
), it becomes a communication buffer between the camera and lens.

The microcomputer PR3 sets the selection signal CLCM to “H” and
When predetermined data is sent as a signal SO in synchronization with CLK, the buffer circuit LCM transmits each buffer signal LCK of 5CLK and So through the camera-lens communication contact.
, DCL is output to the lens. At the same time, lens LN
The buffer signal of the signal DLC from S is output as the signal SI, and the microcomputer PR3 inputs the signal SI as lens data in synchronization with 5CLK.

DDR is a switch detection and display circuit, and the signal CD
Selected when DR is “H”, So and Sl.

Controlled by microcomputer PR3 using 5CLK.

When there is a change in the state of the switch SWS group, the DDR
Q is set to "L" to notify the microcomputer PR5 that there has been a change in the switch. Microcomputer PR3 is 5O9SI, 5
The change state of the switch is detected by communicating a switch change state transmission command using CLK. When the DDR receives the switch change state transmission command, it sends the switch change state to the microcomputer PR.
8 and returns IRQ to "H".

The microcomputer PR8 performs display control by communicating display commands and display data to the DDR using So, SI, and 5CLK. When the DDR receives a display command and display data, it activates the external display member DSP, the display drive transistor in the viewfinder, TR-L, and TR according to the command.
-C, TR-R are set to 0N10FF.

SWI and SW2 are switches that are linked to a release button (not shown), and when the release button is pressed in the first step, SW is activated.
I is turned on, and then SW2 is turned on at the second stage of depression. The microcomputer PR5 performs photometry and automatic focus adjustment when SWI is turned on, and performs exposure control and subsequent film winding when SW2 is turned on.

Note that the switch SW2 is connected to the "interrupt input terminal" of the microcomputer PR8, and even if a program is being executed when SW1 is on, an interrupt is generated by turning on SW2, and control can be immediately transferred to a predetermined interrupt program.

MTRI is for film feeding, MTR2 is for mirror up/
This is a motor for down and shutter spring charging, and forward and reverse rotation is controlled by respective drive circuits MDR1 and MDR2. Microcomputer PR3 to MDRI, MDR2
Signals MIF and M2R are input to.

M2F and M2R are signals for motor control.

MCI and MG2 are magnets for starting the running of the front and rear shutter curtains, respectively, and are energized by signals SMGI, 5MG2, and amplification transistors TRI and TR2, and shutter control is performed by a microcomputer PR3. LPR3 is an in-lens control circuit, and a signal DCL input in synchronization with the circuit LPR3I:LCK is data of a command from the camera to the photographic lens LNS, and the operation of the lens in response to the command is determined in advance.

The control circuit LPR8 analyzes the command according to a predetermined procedure, and determines the operation of focus adjustment and aperture control, and the operation status of each part of the lens (driving status of the focusing optical system, driving status of the diaphragm, etc.) and various parameters from the output DLC. (Open F number, focal length, coefficient of defocus amount vs. movement amount of the focusing optical system, etc.) are output.

Therefore, once the focus adjustment command is sent from the camera, the microcomputer PR5, which is the camera control device, controls all lens driving (
No need to get involved.

The LTMR is a motor that moves the focusing optical system in the optical axis direction to adjust the focus, and is controlled by a control circuit LPR8.

Further, when an aperture control command is sent from the camera, the LPR 3 drives a stepping motor DMTR, which is known for driving an aperture, according to the number of aperture stages sent at the same time. SPC is a photometric sensor for exposure control that receives light from the subject through the photographic lens, and its output is 5SP.
C is input to the analog input terminal of microcomputer PR3,
After A/D conversion, it is used for automatic exposure control according to a predetermined program.

SDR is a drive circuit for the focus detection line sensor device SNS, and is selected when the signal C3DR is “H”.
Controlled by microcomputer PR3 using o, SI, and 5CLK.

Signal 5E given from drive circuit SDR to sensor device SNS
LO, 5ELI is the signal 5ELO from the microcomputer PR3
.

In 5ELI itself, 5ELO = "L', "L" in SEL
”, sensor row pair 5NS-R, 5ELO-“H”,
When φ5ELL-“L”, sensor row pair 5NS-C is set to 5
ELO ``L'' 5 When EL1 = ``H'', sensor row pair 5
This signal selects the sensor row pair 5NS-CH when NS=L, 5ELO="H", and 5ELL-"H".

After the accumulation is completed, set 5ELO and 5ELI appropriately,
Then by sending the read clock RCK, 5
The image signals of the pair of sensor rows selected by ELO and 5ELL are serially output from the output VOUT. The output VIDEO of the sensor drive circuit SDR is an image signal obtained by taking the difference between the image signal VOUT from the sensor device SNS and the dark current output, and then amplifying the difference with a gain determined by the brightness of the subject. The dark current output is an output value of a light-shielded pixel in the sensor array, and the SDR holds the output in a capacitor based on a signal from the microcomputer PR3, and performs differential amplification between this and the image signal. Output VIDEO is microcomputer PR3
is input to the analog input terminal of the microcomputer PR.
8 converts the same signal A/D and stores the digital value in RAM.
Store them sequentially to the specified addresses above (.

Signal TINTER, TINTEC, TIN position, TIN
TECH has sensor row pairs 5NS-R and 5NS-C, respectively.
, SNSL, 5NS-CH is a signal indicating that the charges accumulated are appropriate and the accumulation is completed, and the microcomputer PR3
In response to this, the image signal is read out. The operations of the sensor drive circuit SDR and the sensor device SNS have been previously disclosed by the present applicant in Japanese Patent Application Laid-Open No. 63-216905 as a focus detection device having two pairs of sensor rows, so they will not be described here. Detailed explanation will be omitted.

As described above, the microcomputer PR3 receives the image information of the subject image formed on each pair of sensor rows, and then performs a predetermined focus detection calculation, thereby being able to determine the amount of defocus of the photographing lens.

Next, the automatic focus adjustment device for a camera having the above configuration will be explained according to the flowchart below.

FIGS. 4(a) and 4(b) are flowcharts of the main sequence of this embodiment. A description will be given below according to the flowchart.

(1) When the main switch of the camera is turned on, the initial settings of the camera are made and the main loop (step (2)) is entered.

(2) First, check whether the photometry & distance measurement switch (hereinafter referred to as 5WI) is turned on. If SWI is on, proceed to (13); if SWI is off, proceed to (3)
Branch to.

(3) Turn off the focus display (if the focus display was turned on in the past, turn it off now).

(4) Check whether the distance measurement field of view selection switch is ON or not. If ON, proceed to (5); if OFF, proceed to (6). Note that the ranging field selection switch is one of the switches SWS in FIG. 3.

(5) If the distance measurement field of view selection switch is turned on, enter the distance measurement field of view selection mode. Distance field of view selection mode flag (SE
LECT-MODE).

(6) When the distance measurement field of view selection switch is OFF, check whether the distance measurement field of view selection mode is already entered. If the ranging field of view selection flag (SELECT-MODE) is set, proceed to (7); if cleared, proceed to (11)
Branch to.

(7) If the distance measurement field of view has been changed by the distance measurement field of view change switch, the process branches to (8). The distance measurement field of view is changed using a dial switch. In addition to changing the distance measurement field of view, an automatic distance measurement field selection mode for automatically switching the distance measurement field of view is also set.

(8) When the distance measurement field of view is changed, the memory that stores the distance measurement sensor to be used is rewritten.

(9) Turn on the display in the finder (hereinafter referred to as SI display) corresponding to the distance measurement field of view used for distance measurement.

(10) Check whether the main switch of the camera is ON, and if it is ON, return to (2) and repeat the main loop. If it is OFF, camera operation will be stopped.

(11) If it is not the distance measurement field of view selection mode in (6), check the other switches, and if they are ON, proceed to (12), and if they are OFF, proceed to (10). Since the other switches have no direct relation to the present invention, detailed explanations will be omitted.

(12) Perform processing according to the switch turned on (10
).

The operations of steps (7), (8), and (9) above will be described in detail. These steps are executed as described above (with the distance measurement field of view selection mode being entered). In step (7), for example, a switch (switch group SWS The on/off state of the predetermined switch (of the
Detected by microcomputer PR3 during communication with 1. When the dial operation is detected in step (7), the process proceeds to step (8) as described above. In this embodiment, the sensors are a vertical sensor 5NS-C in the center and a horizontal sensor 5NS-C.
H, left and right sensor"j--5NS-R, 5NS-L are provided, and it has a distance measurement field of view of 3 parts (left, center, right),
Every time a dial operation is detected, the left, center, right, and all sensors are cyclically designated in sequence, and the designated sensors are stored. Note that specifying all sensors means specifying automatic selection mode. Step (9
), the transistors TRL, TRC, and TRL corresponding to the sensors stored in step (8) above should be driven (communication is made from the microcomputer PR3 to the circuit DDR,
Light emitting diode 5P corresponding to the sensor stored above
IL, 5PIC.

One 5PIL is selected and lights up, and the selected field of view is displayed in the finder as described later. It is assumed that when all the sensors are designated, that is, when the automatic selection mode is selected, the light emitting diodes are kept in a non-lighted state.

In steps (7) to (9), the distance measurement field selected by the photographer is displayed in the finder as described above.

Next, the case where the switch SW is turned on will be explained. In this case, the process branches from (2) to (13).

(13) Clear the distance measurement field of view selection mode flag to cancel the distance measurement field of view selection mode.

(14) Turn off the Sr display. With this, the selected and lit light emitting diode is turned off.

(15) First step after SWI is pressed (15
) is executed. If it is the first time (1
Proceed to 6), and branch to (20) from the second time onwards.

(16) Determine whether the distance measurement field of view is specified. If the distance measurement field of view has been specified, the process proceeds to (17), and if the distance measurement field of view is in automatic selection mode, the process branches to (20).

(17) If the distance measurement field of view is specified, S1 display corresponding to the distance measurement field of view is performed in the same manner as in step (9).

(18) WAIT for a certain period of time while displaying Sr.

(19) After waiting for a certain period of time in (18), the Sr display is turned off. (17) to (19), Sr for a certain period of time
The distance measurement field of view is displayed, and is not displayed in automatic selection mode.

(20) In the case of CALL focus detection operation and automatic selection, the AF subroutine performs selection calculation of the distance measurement field of view.

The AF subroutine will be described later.

(21) Determine whether the focus detection result is in focus.

If the focus detection result is in focus, the JF flag is set in the AF subroutine, and here the JF flag is used to make a determination. If the JF flag is cleared, the process proceeds to (22); if it is set, the process branches to (23).

(22) If out of focus, repeat the 0FFL main loop with in-focus display.

(23) Determine whether or not it was in focus last time. If it was in focus last time, go to (28), and if it was out of focus last time and it is in focus this time, go to (28).
Branch to 4).

(24) Turn on the focus display. This focus display is performed by turning on the transistor JFTR and lighting the light emitting diode JFLED using a signal from the DDR.

(25) Turn on the Sr display. If the distance measurement field of view is specified, an S1 display corresponding to the designated distance measurement field of view is performed, and in the case of automatic distance measurement field of view selection, an Sr display corresponding to the distance measurement field of view determined by the automatic selection routine is performed.

(26) Perform WAIT for a certain period of time.

(27) Turn off the Sr display.

(28) Check whether the release switch (SW2) is turned on, and if SW2 is turned on, perform a release process (not shown). If SW2 is OFF, the main loop is repeated.

FIG. 5 is a flowchart showing the focus detection operation in step (20) of FIG. 4(b). The focus detection operation will be explained according to FIG.

(30) AF start. Focus detection is performed by repeatedly executing an AF routine.

(31) Determine whether it is the AFI time. If it is the first time, proceed to (32), and if it is the second time or later, branch to (36).

(32) Determine whether the distance measurement field of view is specified or whether automatic selection mode is selected. If you are in automatic selection mode, proceed to (33).
If the distance measurement field of view is specified, the process branches to (34).

(33) In the automatic ranging field selection mode, focus detection is performed with all ranging sensors. Set flags for all sensors.

(34) If a distance measurement field of view is specified, only the flag of the distance measurement sensor corresponding to the specified distance measurement field of view is set.

(35) Clear parameters for focus detection and initialize the sensor.

(36) Call the sensor storage routine. In this routine, the sensor signal specified by flag (33) or (34) is accumulated, and after the accumulation is completed, the sensor signal is
/D conversion and reading. Furthermore, the sensor signal is corrected and converted into data suitable for focus detection.

(37) A focus detection calculation is performed using a known calculation method from the sensor signal obtained in (36). In this subroutine, the defocus amount of the distance measurement field of view specified is detected.

(38) Determine whether the mode is automatic distance measurement field of view selection mode.

If the distance measurement field of view is automatically selected, the process proceeds to (39), and if the distance measurement field of view is specified, the process branches to (40) without performing (39).

(39) Call the ranging field selection routine. In the ranging field selection routine, one ranging field is selected from the calculated defocus amount according to a predetermined algorithm. As this distance measurement field of view selection algorithm, selection of the defocus amount indicating the object at the closest distance among each defocus amount, selection of the field of view for this defocus amount, etc. are adopted.

(40) Perform focus determination. If the distance measurement field is specified, the defocus amount of the specified distance measurement field is displayed, or if the distance measurement field is automatically selected, the defocus amount of the selected distance measurement field is within the focusing range. A judgment is made.

(41) Branching is performed based on the determination result of (40). In the case of in-focus, the process proceeds to (42), and in the case of out-of-focus, the process branches to (47).

(42) When in focus, set the JF flag.

(43) Determine whether distance measurement field of view is automatically selected. In the case of automatic selection, the process proceeds to (44), and if the distance measurement field of view is specified, the process branches to (49).

(44) Determine whether the lens mode is autofocus or manual focus. For autofocus (
The process proceeds to 45), and branches to (46) in the case of manual focus.

(45) Call the depth/white determination routine. In this routine, if the distance measurement field is in automatic selection mode and autofocus mode is set, the difference between the defocus amount of the automatically selected distance measurement field and the defocus amount of other distance measurement fields is constant. When the value is within the threshold value, the display flag corresponding to the distance measurement field of view is turned on.

(46) Call the in-focus range determination routine. In this routine, in the case of manual focus, it is determined whether the defocus amount of each distance measurement field of view other than the one automatically selected is within the focusing range, and the display flag corresponding to the field of view within the focusing range is turned on.

(47) Determine whether the autofocus mode is the manual focus mode, and if it is the autofocus mode, proceed to (48), and if it is the manual focus mode, proceed to (49).

(48) Call the lens drive routine. In this routine, the lens drive amount is calculated from the defocus amount of the selected distance measurement field of view and the lens is driven.

(49) Return to the main routine.

The operations according to the steps of each flow described above are summarized as follows.

First, when the distance measurement field of view is selected manually, in this case, when the switch SWI is performed, steps (17) (1B) (
The field of view selected in 19) is the light emitting diode 5PIL,
One of 5PIC and 5PIR lights up for a predetermined period of time and is displayed in the viewfinder. After that, in the AF subroutine, the amount of defocus in the manually selected distance measurement field of view is determined, and it is determined whether or not the focus is in focus based on the amount of defocus in that field of view, and if it is out of focus, the amount of defocus is The lens is driven. Then, the focus detection operation is repeated again.

When it is determined that the focus is in focus using the above focus determination, (42) (43
) and proceed to (21) and (23). At this time, if the focus was not determined in the previous focus detection, (24) to (27)
), the focus display light emitting diode JFLED lights up, and the diode corresponding to the selected visual field lights up for a predetermined period of time. Thereafter, the above-mentioned operation is repeated, but when the focus was last time and the focus is again this time, steps (24) to (27) are not executed and SI display is not performed.

In addition, in the manual focus mode, the above display operation is performed without the lens being driven. It is assumed that the autofocus and manual focus modes are selected by a mode setting switch provided on the lens LNS.

Next, the case of automatic selection mode and autofocus mode will be explained.

In this case, the SI display when the switch SW1 is on is not executed and the process proceeds to the AF subroutine. The defocus amount of one predetermined field of view among the defocus amounts of each distance measurement field of view is selected in step (39), and it is determined in (41) whether or not the defocus amount of this selected field of view can be considered to be in focus. When it is determined that the focus is in focus, steps (42) (43) (44) (
45) is executed. In these steps, a visual field that exhibits a defocus amount within a predetermined value with respect to the defocus amount of the selected visual field is determined. Therefore, step (
When displaying 24) to (27), both the automatically selected visual field and the visual field showing a defocus amount close to the defocus amount of the visual field are displayed in SI for a predetermined period of time.

Next, the case where the manual mode is selected will be explained.

In this case, if the automatically selected defocus amount of the visual field is determined to be in focus, it is determined in step (46) whether the defocus amounts of the other visual fields are also in focus.

Therefore, when the selected field of view is in focus, SI display will be performed for each field of view determined to be in focus.

Next, details of the SI display will be explained.

On the light incident surface side of the focus plate FSCRN in this embodiment,
As shown in FIG. 8, a Fresnel lens FSCRN-f is provided, and a light diffusing surface FSCRN-g is formed on the light exit surface side as shown in FIG. There are three display parts AFMK-R, AFMKC, AFMK-
A display body consisting of L is provided corresponding to each distance measurement field of view. As shown in FIG. 9, the display sections AFMK-R, AFMKC, and AFMK-L each display an area indicating a distance measurement range within the photographing screen, and are composed of a large number of prism focusing bodies. At this time, display parts AFMK-R, AFMK-C
, AFMK-L are arranged so that the ridgeline of the prism constituting the display section is substantially perpendicular to the ridgeline direction of the Fresnel lens FSCRN-f.

As a result, the display section efficiently guides the illumination light flux (described later) to the eyepiece side through the refraction effect of the prism, and prevents ghost light generated from the ridge of the Fresnel lens from entering the eyepiece side. Good observation of the image is being carried out.

Display parts AFMK-R, AFMKC, A in this embodiment
The lighting method for FMK-L is light emitting diode SPI.
The light flux from
After guiding the light upward and reflecting it by the quick return mirror QRM, the display section AFMK-R, AF of the focus plate FSCRN
A selected predetermined display section of MK-C and AFMK-L is illuminated. Then, the display unit is connected to the focus plate F.
The object image formed on the SCRN is observed through a finder system.

Figures 6 and 7 are schematic diagrams of the optical paths of the finder system and illumination system shown in Figure 2. Figure 6 is a plan view thereof, and Figure 7 is a side view of the same as seen from the side. . As shown in Figure 6, the light projection lens LNSB has three lens parts LN.
It is composed of SB-R, LNSB-C, and LNSB-RI. Also, the projection lens LNSB is located at 3 on the focus plate FSCRN.
An arbitrary region is selected from among the three regions AFMK-R, AFMKC, and AFMK-L and illuminated. Further, as shown in FIG. 7, the projection lens LNSB illuminates the focus plate FSCRN from an oblique direction at an angle θ.

Focal plate FSCRN illuminated by floodlight lens LNSB
Upper three displays AFMK-R, AFMK-C, AFM
K-L is composed of an aggregate of many prisms,
The illumination light beam incident on each prism is refracted and guided in the direction of the eyepiece EPL. This provides a bright display.

In addition, one of the display parts AFMK-R, AFMK-C, and AFMKL is replaced with a light emitting diode SPI-R, 5P.
By selectively illuminating the I-C, 5PI-L and the projection lens LNSH, it is possible to display the currently selected distance measurement field in red, for example, and the others in black.

By configuring the SI display system in this manner, the selected field of view or the in-focus field of view is displayed superimposed with the subject image in the finder in the above-described operation.

〔Effect of the invention〕

According to the present invention, the viewfinder display corresponding to the subject area is not only displayed corresponding to the selected subject area, but also displayed if the defocus difference from the selected subject area is within a certain threshold. As a result, when distance measurement is performed on the same plane, the display is not just the selected subject area, but all subject areas that are being measured at the same distance, so the photographer is required to know the focus status of each area. I can let you know. Furthermore, even if the selected subject area changes after distance measurement is performed, the displayed subject area will not change if the distance is the same, so the display will not change each time distance measurement is performed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing the configuration of a focus detection device employed in a focus adjustment device according to the present invention, FIG. 2 is a configuration diagram showing the arrangement of the focus adjustment device according to the present invention housed in a camera, FIG. 3 is a circuit diagram showing an embodiment of the camera equipped with the focus detection device shown in FIG. 1; FIGS. 4 and 5 are explanatory diagrams showing flow charts for explaining the operation of the camera shown in FIG. 3; Figure 6 is a plan view showing the optical path of the finder system and illumination system shown in Figure 2 developed, Figure 7 is a side view of the development of Figure 6 seen from the side, and Figure 8 is the focus plate shown in Figure 6. FIG. 9 is a configuration diagram showing the display section of the focusing plate shown in FIG. 6. PH1...Microcomputer SNS...Sensor SPI...Light emitting diode

Claims (3)

[Claims] (1) A defocus amount detection circuit that independently detects the defocus amount of a plurality of different subject regions, a designation means for designating at least one region among the plurality of different subject regions, and a designation means for designating at least one region among the plurality of different subject regions; a calculation means for calculating an area in which the amount of defocus is close to the amount of defocus of the area calculated by the area; an instruction means for instructing each area; and an area calculated by the calculation means and a region specified by the specification means. A focus detection device comprising a drive means for driving an indicating means corresponding to a region. (2) Focus determining means is provided for determining whether the amount of defocus in the area specified by the specifying means is within the focusing range, and when the determining means determines that the area is in focus, the driving means The focus detection device according to claim 1, wherein the focus detection device operates the indicating means corresponding to the area specified by the specifying means and the area calculated by the calculating means. (3) a defocus amount detection circuit that independently detects the defocus amount of a plurality of different subject areas, and a determination circuit that determines for each defocus amount whether or not each defocus amount is within a predetermined range; designation means for designating at least one region among the plurality of different subject regions; and designation means for designating each region;
When the determination circuit determines that the defocus amount of the area specified by the designation means is within a predetermined range, each of the defocus amounts determined by the determination circuit to be within a predetermined range. A focus detection device comprising instruction control means for causing the instruction means to specify an area.