JPH11190871A - Camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camera capable of saving space, advantegeous to miniaturization, and realizing the reduction of the number of parts and the reduction of cost though the camera has both an autofocusing system and a strobe light control system. SOLUTION: This camera is provided with an autofocusing means performing the focusing operation of a photographing lens 2 based on the phase difference of plural images picked up by a phase difference detecting image pickup sensor 15 through the lens 2, and a strobe light control means performing strobe light control by detecting reflected light quantity from a film surface 10 at the time of strobe light photographing. In the camera, the strobe light control means is allowed to detect the reflected light quantity through the sensor 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a camera capable of automatic focusing (autofocus) and strobe light control.

[0002]

2. Description of the Related Art In a conventional camera, especially a single-lens reflex camera using a silver halide film, a method based on a phase difference detection method is often used as a method for adjusting the focus of a photographing lens. This has an optical system that forms a secondary image of a light beam that passes through each of a plurality of pupil regions of a photographing lens with respect to an imaging surface of an image sensor, and a phase difference between these two secondary image data. Is detected, a defocus state is detected, and a focus position is calculated.

On the other hand, when photographing using a strobe,
There is known a flash dimming method in which the amount of reflected light from a film surface is monitored by a sensor having a substantially image-forming relationship with the film surface, and when the amount of reflected light reaches a predetermined value, strobe light emission is terminated.

[0004]

However, conventionally, since a sensor and a detection optical system for autofocus and a sensor and a detection optical system for strobe light control are separately provided, a lot of space is required in the camera. Need and
There is a problem that it is difficult to miniaturize the camera. Also, the fact that two detection systems are required means that a lens as an optical system, a mechanical component as a lens holder, a sensor as a detection system, and each component are required, resulting in an increase in the number of components and an increase in cost. There are also problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a camera which has both an autofocus system and a strobe light control system, is advantageous in space saving and miniaturization, has a small number of parts, and can be manufactured at low cost.

[0006]

In order to achieve the above object, according to the present invention, a focusing operation of a photographing lens is performed based on a phase difference between a plurality of images taken by a phase difference detecting image sensor through a photographing lens. Auto focus means,
In a camera having strobe light control means for performing strobe light control by detecting the amount of reflected light from the film surface at the time of flash shooting, the strobe light control means detects the amount of reflected light through a phase difference detection image sensor. I have.

That is, by using the image sensor for phase difference detection also as a sensor for strobe light control, the number of sensors is reduced, and a part of the phase difference detection optical system is used for strobe light control. Since it can be used as an optical system, space saving, size reduction, and cost reduction can be achieved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a single-lens reflex camera according to a first embodiment of the present invention.
In this figure, 1 is a camera, 2 is a taking lens, 3 is a strobe, and 4 is a photometric lens. The photometric lens 4
The light that has passed through the focus plate 8 is focused on a photometric sensor (SAE) 5.

Reference numeral 6 denotes an eyepiece lens, 7 denotes a condenser lens, 9 denotes a shutter, and 10 denotes a film. Reference numeral 11 denotes a main mirror, which is a quick return mirror in a single-lens reflex camera.

Reference numeral 12 denotes a sub-mirror for autofocus (AF), 13 denotes a mirror, 14 denotes a pair of lenses for generating a phase difference, and 15 denotes an AF sensor (an image sensor for detecting a phase difference). .

Reference numeral 16 denotes a lens for zooming, 17 denotes a lens for focusing drive, and 18 denotes a stop.

Reference numeral 19 denotes a front panel of the strobe light 3;
Is a xenon tube for a strobe, and 21 is a reflector.

In the above configuration, the sub-mirror 12, the mirror 13, and the pair of lenses 14 constitute a phase difference detecting optical system that forms the subject light on the AF sensor 15 in a secondary image. That is, the subject light that has passed through the photographic lens 2 passes through a part of the half mirror portion of the main mirror 11, reaches the sub mirror 12, and is reflected. The sub-mirror 12 is a spherical mirror and functions as a field lens placed on a so-called primary imaging plane.

The light beam reflected by the sub mirror 12 is
Once passing through the primary imaging plane indicated by the point α in FIG. 1, it is guided to the AF mirror 13 and passes through a pair of AF lenses 14. FIG. 4A shows the relationship between the AF lens 14 and the AF sensor 15. The luminous flux from the primary imaging plane α point is
After passing through the pair of AF lenses 14 respectively, secondary images are formed on the areas A and B of the AF sensor 15 respectively. In this embodiment, pixels are arranged in each area of the AF sensor 15 as an area sensor. Auto focus is
The phase difference between the images of the secondary formed A and B areas is calculated, and the focus state is determined to perform the calculation.

FIG. 3 shows an electric circuit of the camera. Reference numeral 51 denotes a microcomputer which controls the sequence of the entire camera, and includes a RAM, a ROM,
An A / D converter, an EEPROM and the like are built in. 52
Denotes a photometric circuit, which has a photometric sensor 5 as a photosensitive unit.

Reference numeral 53 denotes a focus adjustment circuit and a light control circuit, which has an AF sensor 15 as a photosensitive portion. FIG.
As shown in (A), the AF sensor 15 also includes a processing circuit for driving a plurality of sensors in the areas A and B. Here, a specific configuration of the circuit 53 will be described with reference to FIG.

In FIG. 7, reference numerals 71 to 73 denote SPDs (silicon photodiodes) constituting each pixel in the AF sensor 15. Note that in FIG. 7, A in FIG.
(Or B) Some pixels of the area area sensor are extracted and shown. Reference numeral 77 denotes a storage control transfer block. This accumulation control transfer block 77 controls the charge accumulation amount of the area sensor to be a predetermined value, and when the electric charge reaches the predetermined value, transfers the accumulation amount of each pixel to the memory unit 78 and stores the same. Then, the data is sequentially and serially output through the output buffer 79. This output is input to an A / D converter in the microcomputer 51. The above is the configuration of the focus adjustment circuit.

Reference numerals 74 to 76 denote semiconductor SW elements for inputting the photocurrent from the SPDs 71 to 73 to a logarithmic compression circuit portion including a logarithmic compression diode 50 and an operational amplifier 81. Reference numeral 82 denotes an expansion transistor. The base of the expansion transistor 82 is a DA
Controlled by value. 83 is an integrating capacitor. 84
Is a semiconductor switch for controlling the integration operation, and has a START terminal. The level of the integration amount of the capacitor 83 is input to one input terminal of the comparator 85, and when the integration amount reaches a predetermined value (REF2), a STOP signal for stopping light emission of the strobe 3 is output. The above is the configuration of the dimming circuit.

As described above, the dimming circuit includes the AF sensor 15
It is configured to perform strobe dimming using the photocurrent from the camera, so the number of sensors can be reduced compared to the case where a dedicated strobe dimming sensor is provided, and the camera can be made more compact. Can be.

Reference numeral 54 denotes a shutter control circuit, which controls the front curtain and rear curtain of the focal plane shutter in a single-lens reflex camera. Reference numeral 55 denotes a lens control circuit, which is provided in the taking lens 2. This lens control circuit 5
In 5, the diaphragm 18 is driven or the lens 17 for focusing is driven.

Reference numeral 56 denotes a flash control circuit, which is included in the flash 3. The flash control circuit 56 controls the light emission of the xenon tube 20.

Reference numeral 57 denotes a display circuit, which indicates the state of the camera as L
Information is displayed using a CD or the like. For example, the exposure time (T
v) and the control aperture value (Av) are displayed using a 7SEG type LCD.

Reference numeral 58 denotes a film drive circuit for winding and rewinding the film.

Reference numeral 59 denotes a mirror drive circuit which performs up / down control of the main mirror 11 and the sub mirror 12.

Reference numeral 60 denotes a SW (switch) detection circuit.
Various setting operation and operation start switch of camera, especially SW1
(61), SW2 (62) is detected. SW1
Reference numeral (61) denotes a switch that is turned on when the release button is half-pressed, and is for starting photometry and focus adjustment. SW2 (62) is a switch that is turned on when the release button is fully pressed, and is used to start an exposure operation on the film.

Next, the operation of the camera thus configured will be described with reference to the flowcharts shown in FIGS. 5 and 6, circles A, B,
Portions indicated by C are connected by the same character portion.

First, at step 101, SW1 (6
The state of 1) is determined. If the switch SW1 has been pressed, the AF sensor 15 is driven in step 102.
Specifically, the area sensor outputs of the areas A and B shown in FIG. 4 are extracted once. This is equivalent to obtaining the luminance distribution of the subject formed as a secondary image.

Next, at step 103, the amount of defocus is calculated. This is based on the area sensor output values obtained in step 102, as shown in FIG.
The correlation state between the i-th column of the images in the B region is calculated, the shift amount between two images that are originally the same image is calculated, and the shift amount of focus (defocus amount) is detected. In this case, if the out-of-focus states of a plurality of columns are detected, the in-focus states of a plurality of points on the screen can be known. Then, for example, the defocus amount of the point closest to this point is adopted as a representative value, and the lens 17 is driven in the optical axis direction so that the point is most focused at step 104, and the focus is adjusted. Make adjustments.

Next, at step 105, the photometric circuit 52
To obtain subject brightness data.

Further, at step 106, the flash 3
It is determined whether or not charging has been completed. In particular,
Communication between the strobe 3 and the camera 1 is performed.
Is notified to the camera 1 from the strobe 3. In general, a strobe emits light after storing predetermined energy in a capacitor, and is effective for photographing when the charged amount of the capacitor exceeds a predetermined value. . If the charging is not completed, in step 107, as exposure control without using a flash, a shutter time Tv and an aperture value Av at which the exposure amount to the film 10 becomes appropriate only with external light are calculated.
At this time, the ISO sensitivity of the film 10 is taken into consideration.

On the other hand, when charging is completed in step 106, in step 108, exposure control for the film 10 is performed in consideration of both the level of external light and the level of strobe light as exposure control using a strobe. Is calculated so that the shutter speed Tv and the aperture value Av are appropriate. At this time, a DA value for controlling the level of the strobe light amount is calculated. Note that the ISO sensitivity of the film 10 is also taken into account in calculating these values.

Next, at step 109, SW2 (6
It is determined whether or not 2) is ON, and if it is OFF, step 1 is executed.
Return to 01. When it is ON, the sequence is an exposure start sequence. First, at step 110, the main mirror 11 and the sub mirror 12 are raised (evacuated from the imaging optical path). At this time, the camera is in the state shown in FIG.

Next, in step 111, the aperture is driven to the value determined in steps 107 and 108.

Then, in step 112, the front curtain of the shutter is driven. Subsequently, in step 113, the flash 3
It is determined again whether or not the charging state is completed, and if completed, the operation of the dimming circuit is started in step 114. That is, the semiconductor SWs 74 to 76 shown in FIG.
It is turned on by the signal of the L control terminal, and after connecting the SPDs 71 to 73 in common, the photocurrent from these SPDs is input to the logarithmic compression circuit portion (80, 81).
W84 is changed from ON to OFF by the signal of the START control terminal.
The state is shifted to the F state, and the integration operation of the capacitor 83 is started.

Next, in step 116, X (synchro contact) is set to O in response to the completion of running of the shutter front curtain.
N, and the flash 3 starts emitting light.

Here, as shown in FIG. 2, the light from the strobe 3 is projected onto the subject, and the reflected light is
Through the film surface. Part of the light that has reached the film surface is reflected by the film surface, reflected by the AF mirror 13, passes through the AF lens 14, and passes through the AF sensor 1.
Reach 5 Thereby, photocurrent conversion in the SPD is performed.

As described above, the optical system for strobe light control is constituted by a portion of the optical system for detecting a phase difference except for the sub-mirror 12. For this reason, the camera can be made more compact than when the strobe light control optical system is provided separately from the phase difference detection optical system. Note that the image plane viewed from the AF sensor 15 is located at the point α, so that the film plane position cannot be said to be at the perfect image position, and the projection is slightly blurred. The imaging relationship is at a level where sufficient performance can be obtained.

The amount of strobe reflection from the subject (including external light components) is gained at a predetermined magnification by the expansion transistor 82 via the logarithmic compression circuit. The gain is controlled by the base of the transistor 82, that is, the level of the DA value, and the value obtained by multiplying the photocurrent by a predetermined gain is integrated by the capacitor 83. When the integrated amount reaches the predetermined value REF2, that is, when the integrated exposure amount reaches the appropriate exposure amount, the comparator 8
5 outputs a STOP signal, and the microcomputer 51 sends a signal to the strobe control circuit 56 to stop the xenon tube 20 from emitting light.

When it is determined in step 117 that the shutter time has passed the predetermined time, the process proceeds to step 11
At 8, the shutter rear curtain is driven, and the exposure operation for the film 10 ends.

Further, in step 119, the aperture 18 which has been stopped down to the predetermined value is returned to the open side, and in step 120, the mirror system (11, 12) which has been raised is lowered (enters the photographing optical path). In step 121, the film 10 is wound up by one frame, and the unexposed frames are arranged behind the shutter curtain surface. After this, as the initial state again,
It returns to step 101.

In this embodiment, as shown in FIG. 7, a case has been described in which three SPDs are connected in parallel during flash light control to form one light control area, but as shown by the solid line in FIG. The four SPDs adjacent to each other are treated as one group (dotted lines in FIG. 9 correspond to the SPDs indicated by solid lines in FIG. 8), and the area of the area may be coarsened to make each dimming area. .

In the AF sensor 15, there are two regions A and B as the phase difference detection regions, but only one of the regions A and B is used as the dimming region, or both the A and B regions are used. May be used.

When the light control area is largely divided into a plurality of areas, the strobe light emission may be stopped when one of the plurality of divided areas reaches a predetermined level.

[0044]

As described above, according to the present invention,
Since the image sensor for phase difference detection originally used for autofocusing is also used as a sensor for strobe light control, the number of sensors can be reduced. In addition, since a part of the optical system for detecting a phase difference can be used as an optical system for strobe light control, space saving, downsizing of the camera, and cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a camera (at the time of focus adjustment) according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the camera (during exposure).

FIG. 3 is a block diagram of an electric circuit of the camera.

FIG. 4 is a detailed explanatory diagram of an AF sensor in the camera.

FIG. 5 is an operation flowchart of the camera.

FIG. 6 is an operation flowchart of the camera.

FIG. 7 is a configuration diagram of a focus adjustment circuit and a dimming circuit of the camera.

FIG. 8 is an explanatory diagram showing a modified example of the dimming area on the AF sensor in the camera.

FIG. 9 is an explanatory diagram showing a modified example of the dimming area on the AF sensor in the camera.

[Explanation of symbols]

 2 Shooting Lens 3 Strobe 10 Film 12 Submirror 13 AF Mirror 14 AF Lens 15 AF Sensor 71-73 SPD

Claims (2)

[Claims] An auto-focus means for adjusting a focus of the photographing lens based on a phase difference between a plurality of images taken by a phase difference detecting image sensor through a photographing lens; A camera having a strobe light control means for detecting and performing strobe light control, wherein the strobe light control means detects the amount of reflected light through the phase difference detection image sensor. And a phase difference detecting optical system for forming an image of the light passing through the photographing lens on the phase difference detecting image sensor during operation of the autofocusing means. 2. The camera according to claim 1, wherein in operation, at least a part of the optical system for detecting phase difference guides reflected light from a film surface to the imaging sensor for detecting phase difference.