JPH06197270A - Electronic still camera - Google Patents

Abstract

PURPOSE:To realize the electronic still camera employing the TTL dimmer system. CONSTITUTION:A reflected light sensor 11 is provided at the outside of an image pickup area of an image pickup element 3 and detects a light in response to a light b1 reflected by an optical filter 5 and made incident on a differ sensor 7. A difference between a compensated detection light by a compensation circuit 12 and a detected value of the dimmer sensor 7 is integrated by an integration circuit 13 and the flash of an electronic flash 14 is stopped when the integration value reaches a prescribed value. Thus, the effect onto an electronic flash control variable due to the said light b1 is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic still camera using an image pickup device such as a CCD, and more particularly to an electronic still camera using a TTL light control system.

[0002]

2. Description of the Related Art Conventionally, as a strobe light control method used in a single-lens reflex type camera using a silver salt film, a light control sensor receives a diffuse reflection light of an image formed on the film surface and adjusts the light. The so-called TTL method of performing light is becoming mainstream.

FIG. 10 is a schematic block diagram showing the case where the TTL light control system is adopted in an electronic still camera using an image pickup device such as a CCD.

In FIG. 10, reference numeral 1 is a camera unit as a camera body, and 2 is an interchangeable photographing lens unit (hereinafter simply referred to as a lens unit) mounted on the camera unit 1. Camera section 1
3, 3 is an image pickup device such as a CCD, 4 is protective glass for the image pickup device 3, 5 is an optical filter including an optical low-pass filter, an IR cut filter, etc., 6 is a holding frame for the optical filter 5, 6 a is its inner surface, and 7 a Is a dimming sensor, and 8 is a condenser lens of the dimming sensor 7. Further, in the lens unit 2, 9 is a diaphragm.

Symbols a and b represent incident light on the lens portion 2, a represents a light beam having the largest incident angle among the light beams incident on the imaging area of the image sensor 3, and b represents a light beam incident on the optical filter 5. The light rays outside the imaging area having the largest incident angle are shown. In addition, a ₁ is light in which the incident light a is reflected on the glass surface of the optical filter 5, b ₁ is light in which the incident light b is reflected on the glass surface, and b ₂ is light in which the incident light b is virtually extended. .

According to the above construction, of the light incident on the lens portion 2, light having an incident angle smaller than that of the incident light a is imaged in the image pickup area of the image pickup device 3 through the optical filter 5. At this time, the reflected light (not shown) on the image plane is reflected by the optical filter 5.
After passing through, the light is condensed by the condenser lens 8 and received by the light control sensor 7. The light emission amount of a strobe (not shown) is controlled according to the light reception amount.

[0007]

When the TTL light control system used in the above-mentioned silver salt film camera is adopted in the electronic still camera as shown in FIG. 10, the following problems occur. That is, a protective glass 4 and an optical filter 5 composed of an optical low-pass filter, an IR cut filter, etc. are arranged on the front surface of an image pickup device 3 which is generally mounted on an electronic still camera. However, the light may enter the sensor 7 together with the reflected light from the image forming surface, and accurate light control may not be performed.

Then, in FIG. 10, when the conditions under which the reflected lights a ₁ and b _{1 on the} glass surface are incident on the light control sensor 7 were examined, the following was found.

That is, in FIG. 10, it is understood that the reflected light a ₁ of the incident light a by the optical filter 5 does not enter the dimming sensor 7. On the other hand, it can be seen that the reflected light b ₁ of the incident light b from the optical filter 5 enters the light control sensor 7 and may adversely affect the light control photography. In addition, this incident light b
Since is not incident on the image pickup area of the image pickup element 3, it can be seen that the light rays are from the outside of the visual field of photography.

If the incident light b is not a light reflected from a strobe but a light beam from an extremely bright light source such as the sun, the subject is in a strong backlit state, and the photographed image is underexposed. Alternatively, the incident light b may be reflected by the inner surface 6a of the holding frame 6 of the optical filter 5, and flare or the like may occur on the photographic screen.

For the reasons described above, it has been extremely difficult to apply the TTL light control system to an electronic still camera for practical use.

It is an object of the present invention to provide an electronic still camera which solves the above problems and is capable of putting strobe light control by the TTL light control system into practical use.

[0013]

In the first invention,
A reflected light sensor that detects the light that is reflected by the optical filter and that enters the dimming sensor out of the light that enters the imaging area of the image sensor, a correction circuit that corrects the detection value of this reflected light sensor, and its correction value. And an integration circuit for integrating the difference between the detection value of the light control sensor and the detection value of the light control sensor, and a control means for stopping the light emission of the strobe when the integration value reaches a predetermined value.

In the second aspect of the invention, a reflected light sensor for detecting the light that is reflected by the optical filter and is incident on the dimming sensor out of the light that is incident on the outside of the imaging area of the image sensor, and the detection value of the dimming sensor. There is provided control means for controlling the light emission amount of the strobe according to the above, and determination means for determining the success or failure of photographing based on the detection value of the dimming sensor and the detection value of the reflected light sensor.

According to a third aspect of the invention, a reflected light sensor for detecting the light that is reflected by the optical filter and is incident on the dimming sensor out of the light that enters the imaging area of the image sensor, and the detection value of the dimming sensor. There is provided control means for controlling the light emission amount of the strobe according to the above, and judgment means for judging the success or failure of the photographing based on the detection value of the reflected light sensor at the time of non-strobe photographing.

[0016]

In the first aspect of the invention, the influence of the amount of light reflected by the optical filter and incident on the light control sensor on the emission control amount of the strobe is eliminated, and highly accurate emission control is performed only by the imaging light.

According to the second aspect of the invention, immediately after the stroboscopic photographing, it is possible to know whether the photographing succeeds or fails.

In the third aspect of the invention, the detection value of the reflected light sensor is checked immediately after the normal photographing, and if the detected value is below a certain value, it is determined that the photographing is successful, and if the detected value is above a certain value, the photographing is failed. To be done.

[0019]

EXAMPLES Examples 1 to 4 according to claims 1 to 3 will be described below. The first invention is the first and second embodiments, the second invention is the third embodiment, and the third invention is the fourth embodiment. Also,
In each of FIGS. 1 to 9, parts that are substantially the same as those in FIG. 10 are denoted by the same reference numerals, and overlapping description will be omitted.

Example 1. In FIG. 1, reference numeral 10 is a system controller that controls the electronic still camera as a whole.
Reference numeral 1 is a reflected light sensor which is provided in the image pickup device 3 and which substantially detects the reflected light b ₁ , 12 is a correction circuit for correcting the detection value of the reflected light sensor 11, 13 is a correction value of the correction circuit 12 and the dimming sensor 7 The integration circuit that integrates the difference with the detection value and sends the integration result to the system controller 10, 14 is a strobe whose light emission is controlled by the system controller 10 according to the integration result, and 15 is an external operation unit that selects a shooting mode or the like. 1
Reference numeral 6 is a photometric sensor for setting an aperture value and a shutter speed.

FIG. 2 is a front view showing the semiconductor chip surface of the image pickup device 3, and 3a is a photographing area and 3b is a terminal pin. The reflected light sensor 11 is provided below the outside of the imaging area 3a, and the incident light b outside the imaging area 3a, that is, FIG.
The light b ₂ virtually shown in FIG.

According to the above construction, a light beam having an incident angle of the incident light a entering the image pickup area 3a or less is incident on the image pickup area 3a.
Image at a. The reflected light on the image plane is the optical filter 5
Then, the light is received by the light control sensor 7 via the condenser lens 8. At the same time, a part of the incident light b outside the imaging area 3 a is reflected by the glass surface of the optical filter 5, and the reflected light b ₁ is received by the light control sensor 7 via the condenser lens 8. This amount of received light is added to the amount of received light from the image plane to give an error to the amount of light emission control for the strobe 14.

On the other hand, another part of the incident light b (b _{2 in} FIG. 10)
(Light indicated by) passes through the optical filter 5 and the reflected light sensor 11
Is received by. Therefore, the amount of light received by the reflected light sensor 11 substantially corresponds to the reflected light b ₁ . In this embodiment, the detected value of the reflected light sensor 11 is used to eliminate the above error.

Next, the operation of the above configuration will be described with reference to the flowchart of FIG. Unless otherwise specified, the operation is performed by the system controller 10.

First, in step S1, when shooting is performed, the normal shooting mode or the flash shooting mode is selected. This is based on the output value of the photometric sensor 16 of FIG.
It is automatically selected or selected by operating the external operation unit 15. When the normal shooting mode is selected,
Normal shooting is performed in step S2. If the flash photography mode is selected, the photometric sensor 16 is selected in step S3.
The aperture value and shutter speed of the lens unit 2 are set on the basis of the output value of 1), the ISO sensitivity of the image sensor 3, and the like, and a set value for light adjustment is set in step S4. Next, in step S5, a release standby state is set. Here, it is checked in step S6 if the normal shooting mode has been switched to. If it has been switched, the normal photographing in step S2 is performed, and if it has not been switched, the release standby state is continued.

When the release button is pressed in this state,
The aperture is operated in step S7, the shutter is opened in step S8, and the strobe light is emitted in step S9. At this time, the correction circuit 12 obtains the detection output from the reflected light sensor 11 in step S10, and inputs the correction value obtained by adding a certain correction to the detection value to the integration circuit 13. At the same time, the dimming detection value of the dimming sensor 7 is input to the integrating circuit 13, and the integrating circuit 13 integrates the difference between the correction value and the dimming detection value in step S11. The system controller 10 compares the integrated value integrated by the integration circuit 13 with the set value in step S12, and repeats the operations of steps S10 to S12 until the integrated value and the set value match.

When the integrated value and the set value match, the flashing of the strobe 14 is immediately stopped in step S13, and the shutter is closed in step S14.
Open the diaphragm at 15. With the above, one shooting is completed,
It returns to step S5 again. If the normal shooting mode is selected in step S6, the process proceeds to step S2.

Example 2. The reflected light sensor 11 is the image sensor 3
4, the prism 17 may be provided at a part of the optical filter 5 and the reflected light sensor 11 may be provided below the optical filter 5 as shown in FIG.

Example 3. In FIG. 5, reference numeral 18 is a memory for storing the maximum detection value among the detection values of the reflected light sensor 11 and the light control sensor 7, and 19 is a comparison of two maximum detection values obtained from the memory 18 to determine the success or failure of stroboscopic photography. Judge,
A determination unit that notifies the system controller 10, 20 is an integration circuit that integrates the detection value of the dimming sensor 7 and transmits the integrated value to the system controller 10, 21 is a display device that displays a warning, and 22 is a sound that generates a warning sound or the like. It is a department.

FIG. 6 is a front view showing an example of the display device 21, and reference numeral 21a in the drawing is a warning display portion displayed when the determination portion 19 determines that the photographing has failed due to insufficient exposure.

Next, the operation will be described with reference to the flowchart of FIG. Incident light a, b, reflected light a shown in FIG.
According to ₁ and b _1, when the TTL dimming method is adopted in the electronic still camera, the problem is that when the camera is held in the normal position, the one with higher reflectance than the subject is above the subject and It can be seen that this is only the case where it exists in a certain place outside the photographing area 3a of No. 2. That is, except for the special case as described above, the TTL dimming is possible even in the electronic still camera.

In FIG. 7, steps S1 to S9 are executed in the same manner as in FIG. When the strobe 14 emits light in step S9, the integration circuit 20 integrates the output of the dimming sensor 7 in step S71. In step S72, the maximum output values of the dimming sensor 7 and the reflected light sensor 11 are stored in the memory 18.
Remember. The system controller 10 is step S7.
At 3, the integrated value of the output of the light control sensor 7 is compared with the set value. Integration is continued until the integrated value and the set value match, and immediately when the two match, the flashing of the strobe 14 is stopped in step S74, the shutter is closed in step S75, and the aperture is opened in step S76.

Next, in step S77, the maximum output value of the reflected light sensor 11 is adjusted by comparing the maximum output value of the dimming sensor 7 stored in the memory 18 with the maximum output value of the reflected light sensor 11 in the determination unit 19. If the ratio is equal to or higher than a certain ratio with respect to the maximum output value of the optical sensor 7, it is determined that the photographing has failed, the warning sound is generated from the sound generating unit 22 in step S78, and the display device 21 displays the warning sound. After displaying the warning display portion 21a, the process returns to step S5. If the maximum output value of the reflected light sensor 11 is less than or equal to a certain ratio with respect to the maximum output value of the dimming sensor 7 in step S77, it is determined that the shooting has succeeded, and the process immediately proceeds to step S5. Return.

As described above, according to the present embodiment, it is possible to reliably detect the occurrence of a problem in stroboscopic photography when an object having a high reflectance exists in a certain place outside the photographing area 3a. Since the warning can be given by the sound and the display, it is possible to give the warning accurately to the photographer.

The warning display section may be provided in the viewfinder of the electronic still camera. Further, the determination unit 19 may compare the integrated value of the reflected light sensor 11 with the integrated value or the set value of the dimming sensor 7. In that case, comparing the integrated values is advantageous in that more accurate determination can be performed.

Example 4. The electronic still camera in this embodiment has the structure shown in FIG.

FIG. 8 is a front view showing an example of a warning display of the display device 21, 21a is a warning display section showing that the photographed image is underexposed, and 21b is a flare in the photographed image. Is a warning display portion indicating. It is to be noted that, in normal photography, if the warning display portion 21a is displayed with the light amount A received by the reflected light sensor 11 and the warning display portion 21b is displayed with the received light amount B, A <A <in this embodiment. The relationship of B is established.

Next, the operation will be described with reference to the flowchart of FIG.

First, in step S91, the normal shooting mode or the flash shooting mode is selected. When the normal shooting mode is selected, the normal shooting mode M202 is entered, and when the strobe shooting mode is selected, the flash shooting mode M201 is entered, and a release standby state is set in step S92. When the release button is pressed here, the aperture value and the shutter speed of the lens unit 2 are set in step S93 based on the output value of the photometric sensor 16 and the like, and light adjustment is performed according to the ISO sensitivity of the image sensor in step S94. Set the setting value of. Next, the aperture is operated in step S95, the shutter is opened in step S96, and step S9
At 7, the flash 14 emits light.

Then, in step S98, the dimming sensor 7
The output of is integrated by the integrating circuit 20. Step S99
Then, the maximum output values of the dimming sensor 7 and the reflected light sensor 11 are stored in the memory 18. Then, in step S100, the integrated value of the output of the light control sensor 7 is compared with the set value, the integration is continued until the integrated value and the set value match, and immediately when the two match, the light emission of the strobe 14 is stopped in step S101. , The shutter is closed in step S102, and step S
At 103, the aperture is opened.

Next, in step S104, the determination unit 19 compares the maximum output value of the dimming sensor 7 stored in the memory 18 with the maximum output value of the reflected light sensor 11, and the maximum output value of the reflected light sensor 11 is determined. When the ratio is equal to or more than a certain ratio with respect to the maximum output value of the dimming sensor 7, it is determined that the photographing has failed and the exposure is insufficient.
5, the warning sound is generated in the sounding section 22 and the warning display section 21a of the display device 21 is displayed.
Return to the release standby state of 2. If the maximum output value of the reflected light sensor 11 is less than a certain ratio with respect to the maximum output value of the dimming sensor 7 in step S104, it is determined that the shooting has succeeded, and immediately the release standby of step S92 is performed. Return to the state.

Next, the case where the normal photographing mode is selected will be described. First, when the normal shooting mode is selected, a release standby state is set in step S106. When the release button is pressed in this state, the aperture value and the shutter speed are determined based on the output value of the photometric sensor 16 in step S107. Next, in step S108, the diaphragm operates,
The shutter opens in step S109, and step S110.
The image data is stored in the image sensor 3. When a predetermined time has elapsed, the shutter is closed in step S111 and the aperture is opened in step S112.

Next, in step S113, the reflected light sensor 11
Of the detected value is evaluated, and if the detected value exceeds a certain level, a warning to be displayed on the display device 21 is selected in step S114 according to the detected value, and step S114 is performed.
After the warning is displayed on the display device 21 at 115 and the warning sound is generated at the sounding section 22, the process returns to the release standby state of step S106. If the detection value of the reflected light sensor 11 is below a certain level in step S113, the process immediately returns to the release standby state in step S106.

[0044]

As described above, according to the first aspect of the present invention, the reflected light sensor for detecting the reflected light reflected by the optical filter and incident on the dimming sensor is provided, and the detected value is corrected. By integrating the difference from the detection value of the dimming sensor and stopping the strobe emission when the integrated value reaches a predetermined value, the reflection that is reflected by the optical filter and enters the dimming sensor You can offset the effects of light,
As a result, even in the electronic still camera, there is an effect that stroboscopic photography by the TTL light control method can be accurately performed.

According to the second aspect of the invention, the reflected light sensor for detecting the light reflected by the optical filter and incident on the dimming sensor, and the photographing based on the detected value and the detected value of the dimming sensor. Since the determination means for determining success or failure is provided, even if the electronic still camera adopts the TTL light control method, it is possible to know the success or failure of the shooting immediately after the flash shooting.
If the shooting is unsuccessful, the composition of the subject can be changed, and the shooting can be performed again.

According to the third invention, a reflected light sensor for detecting the reflected light from the optical filter which is incident on the dimming sensor,
Since an extremely bright light source outside the photographing range can be detected by providing a judging means for judging the success or failure of the photographing based on the detection value of the reflected light sensor at the time of non-strobe photographing, the electronic still camera can be detected. Even if the TTL dimming method is adopted, there is an effect that it is possible to prevent a shooting failure and to predict underexposure or flare of a captured image due to backlight shooting.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a first invention.

FIG. 2 is a front view showing a semiconductor chip surface of an image sensor.

FIG. 3 is a flowchart showing an operation.

FIG. 4 is a configuration diagram showing another embodiment.

FIG. 5 is a configuration diagram showing an embodiment of the second invention.

FIG. 6 is a front view showing a display example of a display device.

FIG. 7 is a flowchart showing an operation.

FIG. 8 is a front view showing a display example of a display device used in the embodiment of the third invention.

FIG. 9 is a flowchart showing the operation of the embodiment of the third invention.

FIG. 10 is a configuration diagram showing a case where a TTL light control system is adopted in a conventional electronic still camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera section 2 Photographing lens section 3 Imaging element 3a Imaging area 5 Optical filter 7 Light control sensor 10 System controller 11 Reflected light sensor 12 Correction circuit 13 Integration circuit 14 Strobe 19 Judgment section

Claims (3)

[Claims] 1. A dimming sensor for detecting image-forming light in an image pickup area of an image pickup device, and the dimming light reflected by an optical filter arranged on the front surface of the image pickup device out of light incident outside the image pickup area. A reflected light sensor that detects light incident on the sensor, a correction circuit that corrects the detection value of the reflected light sensor, and an integration that integrates the difference between the value corrected by the correction circuit and the detection value of the dimming sensor. An electronic still camera comprising: a circuit; and a control means for stopping the flash light emission when the integrated value of the integration circuit reaches a predetermined value. 2. A dimming sensor for detecting image-forming light in an image pickup area of an image pickup element, and a dimming light reflected by an optical filter arranged in front of the image pickup element out of light incident outside the image pickup area. A reflected light sensor that detects light incident on the sensor, a control unit that controls the amount of strobe light emission according to the detection value of the dimming sensor, a detection value of the dimming sensor, and a detection value of the reflected light sensor. An electronic still camera having a determination means for determining success or failure of photographing based on. 3. A dimming sensor for detecting image-forming light in an image pickup area of an image pickup element, and a dimming light reflected by an optical filter arranged on the front surface of the image pickup element out of light incident outside the image pickup area. A reflected light sensor that detects the light incident on the sensor, a control unit that controls the amount of strobe light emission according to the detection value of the dimming sensor, and an image capturing operation based on the detection value of the reflected light sensor during non-flash photography. An electronic still camera having a determination means for determining success or failure.