JP2002314875A - Photographing apparatus and image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photographing apparatus, and an image pickup device for use therein, in which photometry and light control can be carried out while suppressing error and restriction of design at a low cost by reducing the number of required components or the labor required for adjustment. SOLUTION: First group of pixels 50a in an image pickup device 22 is used for converting the image of an object 3 into image data, and second group of pixels 50b in the image pickup device 22 is used for detecting the quantity of light (e.g. reflected light) from the object 3. When charges stored in the second group of pixels 50b exceed a threshold level, storage of charges of the first group of pixels 50a is stopped and/or charges stored in the first group of pixels 50a are discharged. Since exposure can be controlled without providing a dedicated light receiving element or its optical system required individually in prior art, an electronic still camera is made compact and the degree of freedom is increased in design while reducing the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographing apparatus and an image pickup device, and more particularly to an electronic still camera and the like capable of controlling an exposure amount using an electronic shutter function and a light detection function of a solid-state image pickup device. The present invention relates to a still image photographing apparatus and an image sensor used for the same.

[0002]

2. Description of the Related Art With the development of electronic technology in recent years, electronic still cameras such as digital still cameras capable of converting an optical image into image data and storing the image data have been developed and marketed. By the way, in a case where sufficient reflected light cannot be obtained from a subject at the time of shooting indoors or at night, a general electronic still camera is provided with an automatic light control strobe.

An automatic light control strobe is provided with a light receiving element such as a photodiode in the vicinity of the strobe or a lens. When the emitted light is reflected from a subject, the amount of the reflected light is detected, and when the amount of the reflected light becomes an appropriate amount. Is used to control the amount of exposure by stopping the emission of strobe light.

As in the cameras disclosed in Japanese Patent Publication Nos. 6-87582 and 6-71323, the amount of reflected strobe light is detected by a dedicated light receiving element, but the exposure is controlled by the strobe light. There is also an example in which the light emission is not stopped, but by the operation of an electronic shutter in the image sensor.

[0005]

By the way, when an automatic light control strobe is provided, it is necessary to arrange a light receiving element in front of the electronic still camera in addition to the light emitting portion of the strobe light, and the installation space is appropriately secured. There is a problem that must be done. In particular, since the idea of promoting compact products and giving priority to design is becoming mainstream, it is becoming increasingly difficult to secure an installation space even for small components. Further, in addition to the light receiving element, a semiconductor element for shorting the voltage applied to the strobe light emitting tube for stopping the strobe light is required, and using these elements increases the product cost.

Further, in the case of performing the exposure control with the solid-state imaging device according to the technique described in the above-mentioned publication, a semiconductor device for stopping strobe light emission is not required, but at least a light-receiving device is required. However, the above-described problem of securing the installation space and the problem of cost remain. A similar problem can occur with photometry.

When a light receiving element is used, the angle of incidence and the direction of incidence change due to variations in mounting accuracy, and the actual imaging range and the strobe light detection range may deviate, which is troublesome. If the adjustment is not performed, there is also a problem that accurate light control becomes difficult.

The present invention has been made in view of the above-mentioned problems of the prior art. By reducing the number of necessary parts and the number of adjustment steps, the cost is low, the design is limited, and the error is small. It is an object of the present invention to provide an imaging device capable of photometry or dimming and an imaging device used for the same.

[0009]

According to a first aspect of the present invention, there is provided a photographing apparatus having a light emitting device for illuminating a subject, and an image pickup device having a plurality of pixels arranged two-dimensionally, for photographing the subject. In the imaging device, the image pickup device has a structure capable of discharging charges from an arbitrary pixel without waiting for discharge of charges from other pixels, and a first group of pixels of the image pickup device includes:
A second group of pixels of the image sensor is used to detect an amount of light from the subject, and charges accumulated in the second group of pixels are used to convert a subject image into image data. Light emission of the light emitting device is stopped when the threshold value is exceeded.

According to a second aspect of the present invention, there is provided a photographing apparatus for photographing a subject, wherein the photographing apparatus has a plurality of pixels arranged two-dimensionally. Having a structure capable of discharging electric charge from an arbitrary pixel without waiting for discharge of the pixel, the first group of pixels of the image sensor is used to convert a subject image into image data,
The pixels of the second group of the image sensor are used to detect the amount of light from the subject, and the first group of pixels is used in response to the charge stored in the pixels of the second group exceeding a threshold. And / or discharging of the charge accumulated in the pixels of the first group is performed.

[0013] A third aspect of the present invention is an imaging device having a plurality of pixels arranged two-dimensionally, which is used for an imaging device having a light emitting device for illuminating a subject. The first group of pixels of the image sensor is used to convert a subject image into image data without having to wait for discharge, and a second group of pixels of the image sensor is used. Pixels are used to detect the amount of light from the subject, and the light emission of the light emitting device is stopped in response to the charge stored in the second group of pixels exceeding a threshold value. It is characterized by.

A fourth aspect of the present invention is an image sensor in which a plurality of pixels are two-dimensionally arranged, and can discharge electric charges from an arbitrary pixel without waiting for electric charges to be discharged from other pixels. The first group of pixels of the image sensor is used to convert a subject image into image data, and the second group of pixels of the image sensor is used to detect the amount of light from the subject. In response to the fact that the charge accumulated in the second group of pixels exceeds a threshold value, the charge accumulation of the first group of pixels is stopped, and the charge accumulated in the first group of pixels is At least one of the discharging is performed.

According to a fifth aspect of the present invention, there is provided an image pickup device comprising a plurality of pixels arranged two-dimensionally and a light receiving element disposed between the pixels, wherein the light receiving element extends over two or more pixels. It is characterized by being arranged in a line.

According to a sixth aspect of the present invention, there is provided a photographing apparatus comprising a plurality of pixels arranged two-dimensionally, a photographing lens for forming a subject image on the photographing section, and an outside of the photographing section. And an optical system that guides a part of light from the subject toward the imaging unit from the photographing lens to the light receiving element.

[0015]

According to a first aspect of the present invention, there is provided a photographing apparatus for photographing a subject, comprising: a light emitting device for illuminating the subject; and an image sensor having a plurality of pixels arranged two-dimensionally.
In the image pickup device, without waiting for discharge of charges from other pixels, having a structure capable of discharging charges from any pixel,
A first group of pixels of the image sensor is used to convert a subject image into image data, and a second group of pixels of the image sensor is used to detect an amount of light from the subject.
When the charge accumulated in the pixels of the second group exceeds the threshold value, for example, the light emission of the light emitting device is stopped. Therefore, as in the related art, a dedicated light receiving element and its optical system are separately provided. It is possible to control the light emission of the light emitting device without providing it, thereby achieving a compact imaging device,
The degree of freedom in design is increased, and the cost can be reduced. Note that an image pickup device having a structure capable of discharging electric charge from an arbitrary pixel without waiting for discharge of electric charge from another pixel is, for example, a CMOS type image pickup device which discharges electric charge according to the amount of received light. However, it is not limited to this. The “light from the subject” is a concept including self-light emission of the subject and reflected light of the subject. That is, the present invention (including the following invention) is not limited to strobe light control, and the same operation can be achieved at the time of photometry.

According to a second aspect of the present invention, there is provided a photographing apparatus for photographing a subject, wherein the photographing apparatus has a plurality of pixels arranged two-dimensionally. Having a structure capable of discharging electric charge from an arbitrary pixel without waiting for discharge of the pixel, the first group of pixels of the image sensor is used to convert a subject image into image data,
The pixels of the second group of the image sensor are used to detect the amount of light from the subject, and the first group of pixels is used in response to the charge stored in the pixels of the second group exceeding a threshold. At least one of stopping the charge accumulation of the pixels and discharging the charges accumulated in the pixels of the first group is performed, so that the exposure can be performed without separately providing a dedicated light receiving element or an optical system as in the related art. The control can be performed, whereby the size of the photographing apparatus can be reduced, the degree of freedom in design and design can be increased, and the cost can be reduced.

Further, it is preferable that the image pickup device discharges electric charge from a specific pixel in response to a specific trigger signal.

Further, when image data corresponding to the positions of the pixels of the second group is obtained based on the image data of the pixels of the first group located around the pixels of the second group, it is obtained by photographing. High image quality can be maintained.

Further, if the second group of pixels is a part of the first group of pixels, that is, if image data can be obtained from the second group of pixels, a higher quality image is formed. Can be.

Further, if the image pickup device has a judgment section for judging whether or not the electric charge accumulated in the pixels of the second group exceeds a threshold value, the image pickup device can be constituted by one chip.
The degree of freedom in design is improved. The threshold value at this time is preferably settable from outside.

Further, it is preferable that the image pickup device has an output terminal for outputting electric charges accumulated in the second group of pixels to the outside.

Further, when there are three or more pixels in the second group, the value of the electric charge stored in one of the pixels is higher than the average value of the electric charges stored in the other pixels by a predetermined value or more. In this case, when the charge of the pixel having the higher charge value is excluded and compared with the threshold value, the exposure control can be performed by excluding the high-luminance data of the light-emitting subject such as a light. Exposure control is possible.

It is preferable that the electric charges accumulated in the pixels of the second group be discharged at the same time, since exposure control can be performed quickly and control becomes simple.

Further, when the electric charges accumulated in the pixels of the second group are discharged in accordance with the clock, the number of wirings for discharging can be reduced, and the cost can be reduced.

It is preferable that the amount of the electric charge accumulated in the pixels of the second group can be detected without being discharged, because the luminance of the object can be detected in real time.

Furthermore, by sequentially applying a trigger signal to the pixels of the second group, and discharging the accumulated charges in the order in which the trigger signals are provided, the charges can be discharged in an arbitrary order.

It is preferable that the second group of pixels has at least two charge accumulating portions in order to separately record, for example, an image charge before flashing and an image charge after flashing.

Further, if the pixels of the second group are arranged near the center corresponding to the photographing screen, appropriate exposure control can be performed for a main subject which is often located at the center.

The charges accumulated in the pixels of the second group are discharged in order from the pixel on the center side corresponding to the photographing screen.
Exposure control can be performed quickly.

An image sensor according to a third aspect of the present invention is an image sensor having a plurality of pixels arranged two-dimensionally, which is used for an image capturing apparatus having a light emitting device for illuminating a subject. The first group of pixels of the image sensor is used to convert a subject image into image data without having to wait for discharge, and a second group of pixels of the image sensor is used. Pixels are used to detect the amount of light from the subject, and the light emission of the light emitting device is stopped in response to the electric charge accumulated in the pixels of the second group exceeding a threshold value. As in the prior art, it is possible to control the light emission of the light emitting device without separately providing a dedicated light receiving element and its optical system, thereby making it possible to reduce the size of the photographing device and expand the freedom of design design, Reducing costs It can become.

The image sensor according to the fourth aspect of the present invention is an image sensor in which a plurality of pixels are two-dimensionally arranged, and can discharge charges from an arbitrary pixel without waiting for discharge of charges from other pixels. The first group of pixels of the image sensor is used to convert a subject image into image data, and the second group of pixels of the image sensor is used to detect the amount of light from the subject. In response to the fact that the charge accumulated in the second group of pixels exceeds a threshold value, the charge accumulation of the first group of pixels is stopped, and the charge accumulated in the first group of pixels is Since at least one of ejection is performed, exposure control can be performed without providing a dedicated light receiving element and a separate optical system as in the related art, thereby making it possible to reduce the size of the photographing apparatus and free design design. And increase costs Rukoto is possible.

Further, it is preferable that the image pickup device discharges electric charge from a specific pixel in response to a specific trigger signal.

Further, when image data corresponding to the positions of the pixels of the second group is obtained based on the image data of the pixels of the first group located around the pixels of the second group, it is obtained by photographing. High image quality can be maintained.

Further, if the pixels of the second group are a part of the pixels of the first group, that is, if image data can be obtained from the pixels of the second group, a higher quality image is formed. Can be.

Further, when the image pickup device has a judgment section for judging whether or not the electric charge accumulated in the pixels of the second group exceeds a threshold value, the image pickup device can be constituted by one chip.
The degree of freedom in design is improved. The threshold value at this time is preferably settable from outside.

It is preferable that the image pickup device has an output terminal for outputting charges accumulated in the pixels of the second group to the outside.

Further, when there are three or more pixels in the second group, the value of the electric charge stored in one of the pixels is higher than the average value of the electric charges stored in the other pixels by a predetermined value or more. In this case, when the charge of the pixel having the higher charge value is excluded and compared with the threshold value, the exposure control can be performed by excluding the high-luminance data of the light-emitting subject such as a light. Exposure control is possible.

It is preferable that the electric charges accumulated in the pixels of the second group be discharged at the same time, since exposure control can be performed quickly and control becomes simple.

Further, when the electric charges accumulated in the pixels of the second group are discharged in response to a clock, the number of wirings for discharging can be reduced, and the cost can be reduced.

It is preferable that the amount of the electric charge accumulated in the pixels of the second group can be detected without being discharged, because the luminance of the object can be detected in real time.

Furthermore, by sequentially applying a trigger signal to the pixels of the second group and discharging the accumulated charges in the order in which the trigger signals are provided, the charges can be discharged in an arbitrary order.

It is preferable that the pixels of the second group have at least two charge accumulating portions in order to separately record, for example, an image charge before the flash light emission and an image charge after the light emission.

Further, if the pixels of the second group are arranged near the center corresponding to the photographing screen, appropriate exposure control can be performed for a main subject which is often located at the center.

When the electric charge accumulated in the pixels of the second group is discharged in order from the pixel on the center side corresponding to the photographing screen, the electric charge accumulated in the central group is often reduced.
Exposure control can be performed quickly.

According to the fifth aspect of the present invention, the image pickup device includes a plurality of pixels arranged two-dimensionally and a light receiving element disposed between the pixels, wherein the light receiving element is provided with two or more light receiving elements. Since they are arranged in a line over the pixels, the wiring for extracting signals from the light receiving element can be shortened, and the configuration can be simplified.

According to the sixth aspect of the present invention, there is provided an image pickup section comprising a plurality of pixels arranged two-dimensionally, a photographing lens for forming a subject image on the image pickup section, and the image pickup section. A light-receiving element disposed outside of the camera, and an optical system that guides a part of light from the subject toward the imaging unit from the photographing lens to the light-receiving element. Since it can also be used as a photographic lens, it is possible to simplify the configuration and improve the degree of freedom in the design of the photographic device. The light receiving element includes a photodiode and a phototransistor, but may be a pixel or a group of pixels.

In the image pickup device according to the present invention, the pixels of the second group are kept in a state where the output signal (accumulated charges) is discharged, that is, in an ON state (discharge state).
Alternatively, it is conceivable to take out the output by periodically accessing at high speed. When there are a plurality of pixels in the second group, it is preferable that the plurality of pixels be simultaneously turned on (discharged state) or that scanning be performed while switching pixels at high speed. This is detected at one or a plurality of locations. For example, when strobe light emission is performed, a short-term output change immediately after the light emission is observed by detecting the charges of the pixels of the second group. When the threshold value is exceeded, a signal for stopping the emission of strobe light is output. If the second group of pixels is used for exposure control (only for data acquisition), a pixel signal for image data of the second group of pixels is obtained by interpolating from peripheral pixels later like the defective pixel. Can be.

In addition to using a part of the two-dimensionally arranged pixels, a second group of pixels dedicated to exposure control data acquisition may be provided in the imaging unit. For example, when a light receiving element is provided between pixels, the effect on image quality is reduced,
There are problems such as an increase in the wiring area. It is also conceivable to arrange a pixel or a light receiving element around the imaging unit. It is also conceivable to provide light receiving elements arranged in a line instead of a single pixel. The charge accumulated in the second group of pixels is
It is also conceivable to divide the data into exposure control data and image data. At this time, the output of the pixel is smaller than the output of the pixel for extracting the image data. However, amplification of the output has the advantage that the deterioration of the image quality is smaller than that obtained by interpolation from surrounding pixels.

Further, a pixel having an element structure capable of nondestructive readout (that is, a pixel which can determine the amount of accumulated electric charge without discharging electric charge) is provided for obtaining exposure control data. The signals of the second group of pixels can also be used as image data. In this case, for example, it is preferable to compare data read before the flash emission with data read after the flash emission, and terminate the exposure when the data exceeds a preset light control level.

Further, when a part of the pixels of the first group is used as the pixels of the second group, when a specific first group of pixels is used fixedly, or when an arbitrary first group of pixels is selected. In some cases, the pixels are adaptively used as the second group of pixels. When the pixel is fixed to a specific first group of pixels or when a second group of pixels is provided exclusively, a color filter may not be mounted, or a filter suitable for a strobe light source or the like may be mounted. Regarding the color filter, if the pixel adopts an RGB (red, green, blue) filter, the spectral sensitivity characteristics of the light receiving element are secured by selecting the light receiving element so that each of the RGB filters has a certain ratio. it can. For example, there is a method of using four adjacent pixels as light receiving elements. At this time, the spectral sensitivity characteristic of the light receiving element can be changed by changing the ratio of the RGB pixels.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the present embodiment with reference to the drawings, an outline of a CMOS type image pickup device will be described. FIG. 1 is an equivalent circuit diagram of a CMOS image sensor. Although only a single pixel 50 is shown in FIG. 1, the pixels 50 are two-dimensionally arranged. A timing generator 5 is provided outside the pixel 50.
1, vertical shift register 52, horizontal shift register 5
3. Circuits such as the output amplifier 55 are configured. The vertical shift register 52 is a register for selecting a scanning line, and the horizontal shift register 53 is a register for selecting pixels 5 in the same scanning line.
This register selects 0. The timing generator 51 controls the entire sensor including these components. In addition, in addition to the above configuration, a CDS circuit, an AD converter, a signal processing circuit, and the like may be incorporated.

The settings inside the timing generator 51 can be made externally by serial communication. In FIG. 1, only the command input is viewed from the arrow, but it is assumed that two-wire or three-wire serial communication is performed. With this serial communication, it is possible to set and change registers in the timing generator 51. As an exposure control signal, a dedicated terminal (T
RG1, TRG2) are provided, so that the data is transmitted through such terminals.

There are several methods for controlling the image pickup device. In this embodiment, the trigger signal T
Exposure starts at the rising edge of the pulse of RG1, and ends at the falling edge of the pulse. And
When the trigger signal TRG2 rises after the trigger signal TRG1 rises and the trigger signal TRG2 rises after the rise of the pulse of the trigger signal TRG1 and before the fall of the pulse, the exposure ends.

More specifically, the operation of each unit will be described. In FIG. 1, the light receiving operation of the pixel 50 in the sweeping operation is performed by the power supply Vrst1 via the MOS transistor Q2.
This is performed by an optical sensor unit (that is, a photodiode) D <b> 1 connected to the control unit. When sweeping out the charge of the photodiode D1, the output signal RG1 of the timing generator 51 is controlled and the transistor Q2 is turned on to sweep out the charge to the power supply Vrst1. By turning on the MOS transistors Q2 of all the pixels, the charges of all the photodiodes are swept out, and the transistors Q2
Exposure is started at the point when is turned off. Such a portion corresponds to a charge discharging portion.

For charge transfer, the photodiode D
1 is a capacitor C1 via a MOS transistor Q1.
It is connected to the. This portion corresponds to a charge storage unit.
Controlling the output signal SG of the timing generator 51,
By turning on the MOS transistors Q1 of all the pixels, the charge of the photodiode D1 is transferred to the capacitor C1. Further, the exposure is completed by turning off the transistor Q1.

Next, the reading of charges will be described.
The charge accumulated in the capacitor C1 of each pixel is turned on by turning on the MOS transistor Q5.
, One pixel (or one line) is read out to the outside. The pixel is selected by the vertical shift register 52 and the horizontal shift register 53 (here, the transistor Q6 is turned on).
This is done by specifying an address. That is,
The charge can be read out only from the addressed pixel. At this time, it is possible to read out the charge as it is, but since it is easily affected by noise, in this embodiment, the charge is once converted into a voltage and output.

Thereafter, the charge storage section is reset. More specifically, after the reading is completed, the MOS transistor Q3 is simultaneously turned on until the next photographing is started, thereby sweeping out the charge of the capacitor C1 to the power supply Vrst2 (clearing, that is, the power supply Vr2).
reset to st2). At this time, it is preferable that all pixels are simultaneously performed, since the amount of dark current noise between pixels can be equalized. However, when the amount of noise generation is sufficiently small, it may be performed pixel by pixel after reading is completed. The electric charge is amplified by the amplifier 55 of the output unit and output.

The reset function of the photodiode D1 can be omitted. In that case, the transistor Q2 will be omitted. In this case, by transferring the electric charge to the capacitor C1, the photodiode D1 can be cleared and the exposure can be started therefrom. The charge transferred to the capacitor C1 is read out during the exposure period and discarded.

As a modification, a case where a nonvolatile memory (charge storage section) is provided will be described. In an image sensor including a non-volatile charge storage unit and a non-volatile charge storage unit, first, all the pixels are simultaneously transferred from the optical sensor unit to the non-volatile charge storage unit, and then the pixels are sequentially transferred to the non-volatile charge storage unit. It is preferable to transfer the charge to the charge storage unit. This is because a flash memory or the like generally has a slow writing speed and takes a long time to write, so that the writing timing is adjusted.

FIG. 2 is a schematic configuration diagram of an image sensor circuit 20 including the image sensor of FIG. Each pixel 50 (FIG. 1) of the imaging unit 54 in which the pixels 50 shown in FIG. 1 are two-dimensionally arranged.
Are controlled and operated by the vertical shift register 52 and the horizontal shift register 53 controlled by the image sensor control circuit 23 (including the timing generator) which receives the control signal from the MPU 27, as described above. I have.

In the present embodiment, some of the pixels 50 are pixels (second group of pixels) for detecting light from a subject for exposure control, and the remaining pixels (first group of pixels).
Has a function of converting a subject image into image data. Therefore, the output signal from the first group of pixels is output from the output terminal 55a.
, And is output to the outside of the image sensor circuit 20. The output signal from the second group of pixels is amplified by the output amplifier 56 via the output terminal 56a. It is compared with a photometric level or a dimming level (that is, a threshold), and the result is output to the image sensor control circuit 23. As shown in FIG. 2, the imaging unit 54, the vertical shift register 52, the horizontal shift register 53, the image sensor control circuit 23, the output amplifiers 55 and 56, and the comparator 7 are integrated into one chip. Although not shown, a one-chip circuit includes a register for setting a dimming level and a DA.
It also has a built-in converter and has a communication function for changing the dimming level by externally rewriting this register.

FIG. 3 is a schematic configuration diagram showing an array of pixels in the imaging section 54. The second group of pixels 50b (shown by hatching) are arranged at predetermined intervals in the first group of pixels 50a arranged two-dimensionally. In this embodiment, a low-cost configuration can be achieved by using a part of pixels for obtaining image data as exposure control pixels in a general-purpose CMOS image sensor. According to this configuration, a part of the image data is used as exposure control data, so that a state equivalent to a pixel defect (a so-called black defect) occurs at the position of the second group of pixels. However, such a pixel defect can be corrected from the image data of the surrounding pixels, as in the case of a black defect that can usually occur, so that no major problem occurs. The number of pixels 50b in the second group is preferably about 30 to 100, assuming that the pixels 50a in the first group have 1M pixels. It is preferable that the second group of pixels 50b is specified by an address and is in a state of constantly outputting. In such a case, the outputs of a plurality of pixels can be combined into one output. Second group of pixels 50
b may be arranged only at the center, or may be arranged at predetermined intervals over the entire imaging unit 50.

FIG. 4 is a wiring diagram for extracting signals when the imaging section of FIG. 3 is used. As shown in FIG. 4, the first group of pixels 50a and the second group of pixels 50b
The output amplifier 55,
56.

FIG. 5 is a schematic configuration diagram showing an array of pixels in the imaging section 54 according to a modification of the present embodiment.
A second group of pixels 50b (shown by hatching) is arranged between the first group of pixels 50a arranged two-dimensionally. In the present embodiment, although it is necessary to manufacture the CMOS type imaging device exclusively (including the wiring dedicated to the second group of pixels 50b), unlike the configuration of FIG. Can be kept high.

FIG. 6 is a wiring diagram for extracting signals when the image pickup section of FIG. 5 is used. As shown in FIG. 6, the first group of pixels 50a and the second group of pixels 50b
The output amplifier 55,
56.

FIG. 7 is a schematic configuration diagram showing an array of pixels in an imaging section 54 according to another modification. Light receiving elements 150b (shown by hatching) arranged in a line are arranged between the first group of pixels 50a arranged two-dimensionally. Also in the present embodiment, although it is necessary to specially manufacture the CMOS type imaging device, unlike the configuration of FIG. 3, no pixel defect occurs, and a sufficient amount can be obtained by effectively utilizing the space between the pixels 50a. Can be obtained, and the length of the wiring for the light receiving element 150b can be shortened. All first group pixels 50
Although it is preferable to provide the light receiving element 150b between a,
It may be provided in two (or more) steps. As the light receiving element 150b, a photodiode or a phototransistor can be used instead of the pixel.

FIG. 8 is a wiring diagram for extracting signals when the image pickup unit of FIG. 7 is used. As shown in FIG. 8, the first group of pixels 50a and the light receiving element 150b are connected to the output amplifiers 55 and 5 by independent wirings W2 and W1, respectively.
6 are connected.

As a method for reading out signals from the pixels of the second group, there are the following methods. 1) A method in which all light receiving elements are accessed simultaneously, signals are read out at the same time, and the signals are added and taken out. In this case, the XY address is specified so that the output transistors of all the light receiving elements are turned on, and the signal is read. 2) A method of switching and reading out one pixel at a time at high speed. In this case, it is necessary to read out the signal at a time interval sufficiently earlier than the emission time of the strobe light in consideration of the use of the strobe. The signals read out pixel by pixel are added externally. 3) A method combining the above. In this method, the light receiving elements are divided into several groups and read out for each group.

In the method (1), since signals are added and detected at once, photometry with a high response speed can be performed, and photometry can be performed without using a complicated circuit or a complicated photometric algorithm. . The method 2) depends on the number of light receiving elements, for example, since the light emission time of the strobe light is about several hundred μs, but when the number of pixels of the second group is about 100, it is several tens ns or less, preferably about 10 ns or less. However, fine photometric control as described later can be performed. The method 3) has both advantages and disadvantages in between. For example, signals of the light receiving elements for one column are simultaneously read, and the signals are sequentially switched and read over all columns.

In the case of individually reading, signals can be used adaptively. In the case of a CMOS image sensor, a signal can be read for each pixel, so that, for example, at the time of stroboscopic photographing, a signal can be used by focusing on a pixel that largely changes after stroboscopic light emission. At first, signals are read out from all the pixels of the second group. If there are pixels whose change is large after the strobe light emission, some or all of them are selected and only the signals from the pixels are read out. In other words, for example, when a person is photographed, photometry is performed by focusing on a portion of the face, body, or the like where the amount of reflected light is to be measured. Further, in this case, the readout cycle is shortened and the resolution in the time axis direction is increased by the decrease in the number of pixels of the second group used,
Photometry with higher accuracy is possible. When a dedicated second group of pixels is provided, a readout circuit can also be provided exclusively. Although the output circuit can be provided for exclusive use, it can be shared with the output of the image signal.

FIG. 9 is a diagram showing a schematic configuration of an electronic still camera which is an example of the imaging apparatus according to the present embodiment. In FIG. 9, an MPU 27 determines an aperture and a shutter speed, and outputs a control signal to various circuits.
Reference numeral 24 denotes a release switch serving as signal output means,
25 is turned on by the battery BT.
A power switch for supplying power to the PU 27 and the like and shutting off the power by turning off the power.
This is a light emitting circuit that receives a trigger signal (light emission start signal) from U27 and causes the strobe light 2, which is a light emitting device, to emit light. Further, reference numeral 21 denotes a photographing lens for condensing reflected light from the subject 3, and reference numeral 22 denotes a CMOS image sensor shown in FIG. Reference numeral 23 denotes an image sensor control circuit that controls a light exposure of the image sensor 22 in response to a stop signal from the comparator 7 serving as a determination unit. The operation of the electronic still camera configured as described above is as follows.

The operation of the present embodiment when performing flash light control will be described with reference to the flash emission characteristic diagram shown in FIG. A curve f shown in FIG. 10 is a strobe light emission curve when the strobe light 2 is fully emitted. In the present embodiment, based on a preset shutter time in the strobe mode (for example, 1/60 second, corresponding to t1 to ts in the drawing), the longest emission time T2 of the strobe 2 from the time ts when the shutter closes. (Usually 50μs to 500μ
At time tx, which is short by s), the strobe light 2 is caused to emit light (the amount of light emission is not controlled, and full emission is sufficient). In the present embodiment, first, the second operation of the image sensor 22 through the photographing lens 21 is performed based on the release operation of the release button.
The brightness of the object is measured by the light incident on the group of pixels 50b (FIG. 3), and the aperture and shutter time are determined by the MPU 27. If the shutter time exceeds 1/60 second, the flash mode is used. Is set automatically. Now, at time t1, the image sensor control circuit 23
Supplies the signal TRG1 to the timing generator 51, thereby sweeping out the charges in the photosensor portion (the photodiode D1 in FIG. 1) to start the exposure.

Next, after a lapse of a predetermined time, at time tx, M
When a trigger is input from the PU 27, the light emitting circuit 200 causes the strobe light 2 to emit light. The subject 3 is illuminated by strobe light emission. Light (for example, reflected light) from the subject 3 enters the image sensor 22 via the photographing lens 21. During this time, the amount of strobe light increases rapidly as shown in FIG.
At time tx, an integration start signal enters an integration circuit (not shown) simultaneously with the strobe light emission signal from the MPU 27. Thus, the integration of the strobe light starts.

The integration circuit integrates the output of the second group of pixels 50b, and the output increases with time. Then, the time t when the output reaches a predetermined reference dimming level
At s', the comparator 7 operates and outputs a stop signal. The stop signal may be output from the comparator 7 through the MPU 27.

Upon receiving the stop signal, the image sensor control circuit 23 outputs a signal TRG2 to the timing generator 51 (FIG. 1), thereby terminating the exposure operation of the image sensor 22. Thereby, the image information of the subject 3 in the optimal exposure state is stored in the charge storage unit in each pixel. At this time, the integration time of the image sensor 22 is from t1 to t.
s' and (ts-t) from the first setting (t1 to ts).
s'), but this quantity is very short, (ts-
Since t1≫ts−ts ′), there is no problem, and the shutter speed originally in the flash mode (for example, 1/6
0 seconds t1 to ts) is not a problem since it is not a particularly significant number.

On the other hand, the flash 2 continues to emit light even after the time ts' has elapsed, and is extinguished at the time ts (the time during which the flash 2 emits light is T2). An area A is an exposure amount for integrating into the image by the image sensor 22 and an area B is an exposure amount for not contributing to image formation. As described above, according to the present embodiment, the charge amount at the time when the optimum exposure amount is reached can be stored in the storage unit without stopping the strobe light emission in which it is difficult to precisely control the light emission amount. . As a result, the exposure amount can be controlled with high accuracy at the time of flash emission with a simple configuration.

The above-described concept of exposure control can be applied to daytime synchronization (an object image with an appropriate exposure can be obtained by emitting a strobe light when the object is backlit, etc.). Shutter time (1/60 of the above example)
Seconds), depending on the brightness of the subject,
This is the same as the previous example. However, if the shutter time is too short at this time, the above-mentioned ts-t1≫ts-ts' does not hold and affects the exposure accuracy. Therefore, at this time, the aperture is made small and the shutter time is made somewhat longer. Ingenuity is required. This will be described with an example. For example, suppose that the set exposure amount is reached immediately after the strobe light is emitted and the shutter is closed. In other words, the shift of the shutter time by almost the longest light emission time of the strobe (ts-ts')
Suppose there was.

In order to make the shift of the shutter time within -0.2 EV, if the flash emission time is set to yms and the shutter speed xms for flash shooting, y <(1-2)
^{-0. 2} ) x Therefore, the strobe light emission time is 517 μs or less to enable shutter speeds up to 1/250, the strobe light emission time is 258 μs or less to enable shutter speeds up to 1/500, and the strobe light emission is possible up to 1/1000. The time is 129 μs or less. Similarly, to make the shift at the shutter time within -0.4 EV, y
<( ^1-2−0.4 ) x, the shutter speed 1 /
968 μs or less for up to 250, 4 for up to 1/500
84 μs or less, up to 1/1000, 242 μs or less,
If it is up to 1/2000, it is 121 μs or less, and if the shift in shutter time is large, the subject to which the strobe light strikes is properly exposed, but the portion where the strobe light does not reach will be underexposed or overexposed.

Also, the longest light emission time of the strobe (50 μs to 5
00 μs) is not fixed, but can be linked to distance information from an AF (auto focus) system (not shown). For example, if (subject distance) × (aperture) is small in consideration of the set aperture, the amount of light emission is small, and ts−tx can be estimated to be small. Conversely, if (subject distance) × (aperture) is large, a large light emission amount is required, and ts−tx can be estimated long.

FIG. 11 shows the flash emission characteristics when (subject distance) × (aperture) is small, and FIG. 12 shows (subject distance)
FIG. 6 is a diagram illustrating strobe light emission characteristics when x (aperture) is large. As described above, when (subject distance) × (aperture) is small, the amount of light emission can be small.
As shown in FIG. On the other hand, when (subject distance) × (aperture) is large, a large amount of light emission is required, and the area A becomes large as shown in FIG.

By using such a method, even if the shutter time becomes short at the time of the daytime synchronization as described above, t
Since s'-tx is estimated, ts-ts' can be shortened, and the error can be reduced as compared with the above example. Accordingly, faster daytime synchronization is possible.
Of course, when ts 'is later than ts, the initially set ts is ignored, and integration of the solid-state imaging device is continued until ts', that is, until a stop signal is output. However, although not shown in the figure, when the amount of light emission is insufficient and no stop signal is output, the charge accumulated in the optical sensor unit is discharged at either ts or ts'. That is, the shutter is closed. Alternatively, after a longer time than ts or ts' elapses, the shutter speed at the camera shake limit (for example, 1 /
60 seconds) or the slowest shutter time (for example, 1 /
Exposure may be terminated by forcibly transferring the charge stored in the optical sensor unit (for example, 8 seconds).

Next, the photographing control flow of this embodiment shown in FIG. 13 will be described. Step S101 in FIG.
Then, when the photographer turns on the main switch, power is supplied to each unit in step S102, and step S103 is performed.
Thus, a capacitor (not shown) in the strobe light emitting circuit 200 is charged. Strobe charging may be performed only when necessary. Furthermore, the process waits for the photographer to press a release button (not shown) in step S104, and when the release button is pressed, the MPU2 is pressed in step S105.
7 denotes a second group of pixels 50b (or a first group of pixels 50a,
Alternatively, exposure control for exposure control is started using the outputs of the two), and after the exposure control is completed in step S106,
In step S107, it is determined whether strobe light emission is necessary. There are various possible modes of exposure control.
The optimum exposure condition can be determined based on the data continuously read from the group of pixels 50b.

At this time, if it is determined that strobe light emission is necessary because the illuminance of the subject is low, the MPU 27 starts exposure in step S108, and sends a trigger signal to the light emission circuit 200 in step S109 to cause the strobe light 2 to emit light. .

After the start of the exposure or immediately before the light emission, the signal reading from the pixels 50b of the second group is started. The signal from each pixel is read simultaneously at each clock and the output value is checked. That is, the outputs of the respective pixels are added and read. Starting readout before the strobe light emission corresponds to resetting each pixel before the light emission.

In step S110, the second group of pixels 50b
It is determined whether or not the amount of strobe light emission exceeds a predetermined value based on the output from. If the MPU 27 determines that the strobe light emission amount has exceeded the predetermined value, the MPU 27 terminates the exposure (stops charge accumulation or discharge of the first group of pixels 50a). On the other hand, if the MPU 27 determines that the flash emission amount has not exceeded, the MPU 27 waits until the scheduled exposure time ends in step S113, and completes the exposure operation in step S114.

On the other hand, if the MPU 27 determines that strobe light emission is unnecessary because the subject illuminance is high, the MPU 27 starts exposure in step S112 without performing strobe light emission, and ends the scheduled exposure time in step S113. The exposure operation is completed in step S114.

Thereafter, in step S115, the MPU 27
Reads an image signal from the first group of pixels 50a and stores it in a memory (not shown) in step S116. The power supply is cut off as necessary (step S117).

If the above control is supplementarily explained, after the flash is fired, the second read out after the flash is triggered by the flash.
The pixel signals of the group of pixels 50b are integrated for each clock. The integrated value is compared with a preset threshold (light control level) in the comparator 7, and when the threshold is reached, a stop signal is output to the image sensor control circuit.
The exposure is terminated by closing the electronic shutter of the image sensor.

As a method of extracting a signal, in addition to reading the signal every clock, the output may be extracted in a state where the signal line is directly connected to the pixel once reset and cleared. In this case, the strobe light is integrated by the pixel. A signal obtained by adding the outputs of the pixels (light receiving elements) is preferably compared by the comparator 7. As will be described later with reference to FIG. 14, in some cases, the second group of pixels 50b can be selected. For example, a pixel receiving light from a high-luminance subject is referred to as a second pixel.
In the case of a group of pixels, the intensity of strobe light may not be negligible. When the output of such a pixel is used for dimming control, an error may occur in the detection of the amount of strobe light. In order to eliminate this, the second group of pixels is scanned in advance to detect whether or not the high-luminance object light is received, and if so, the pixel is excluded so as not to be used as a light receiving element. It is.
However, since the strobe light emits relatively strong light in a short time, the influence of normal light within the light emission time may be negligible, and in that case, the selection operation may be omitted.

In this embodiment, when the output of the second group of pixels reaches a preset dimming level, a stop signal is output from the comparator 7 and input to the image sensor control circuit 23. Thereby, the image sensor control circuit ends the exposure of the image sensor. The above functions can be integrated on the image sensor 22. The setting of the dimming level and the like may be performed from outside.

When the pixels of the color image sensor are used as the pixels of the second group, there are a method of representing BGR filters by green pixels and a method of selecting and representing each BGR pixel in a well-balanced manner. It is possible to mount another color filter only on the second group of pixels, or it is also possible not to mount another color filter.

In this embodiment, when the output of the second group of pixels 50b reaches a preset dimming level, a stop signal is output to the image sensor control circuit 23 and the image sensor 22
Instead, the electronic shutter is closed to end the exposure. Alternatively, when the output of the second group of pixels 50b reaches a preset dimming level, a light emission stop signal is sent from the MPU 27 to the strobe light emitting circuit 200. It is also possible to forcibly end the light emission of the strobe and to end the exposure after the scheduled exposure time.

FIG. 14 is a diagram showing a photographing control flow for explaining a modification of the flash exposure control of FIG. 13 in detail. This modification shows control when light from a high-brightness object such as a light-emitting body such as a light enters the second group of pixels. After the photometry is completed in step S106 in FIG. 13, step S2 in FIG.
At 01, the MPU 27 determines whether or not the mode for dividing the second group of pixels 50b that has received light from the high-luminance subject is selected. If the MPU 27 determines that the mode of dividing pixels has been selected, the MPU 27 proceeds to step S20.
In step 2, the second group of pixels 50b is scanned at high speed (the output of each pixel is checked). Then, in step S203, the output is compared with the specified value. If the output of any of the pixels is lower than the specified value (threshold), it is determined that the light is not from a high-luminance object, and the MPU is determined.
27 registers such a pixel (step S204).
On the other hand, if the output of any of the pixels is equal to or greater than a specified value (threshold), it is determined that the light is from a high-luminance subject, and the MPU 2
In step S205, the flash light control is performed excluding such pixels (step S205). The threshold may be a fixed value, but 3
When there is more than one pixel signal, the average value may be obtained, and pixel signals far apart from the average value may be excluded.

In step S206, all the pixels 5 in the second group
0b is completed, or in step S20
1, a second group of pixels 50 receiving light from a high-brightness subject
If it is determined that the mode for dividing b has not been selected,
The MPU 27 starts exposure in step S207, resets the second group of pixels 50b in step S208, and causes the strobe 2 to emit light via the strobe light emitting circuit 200 in step S209. Then, in step S210, M
The PU 27 reads the signal output from the second group of pixels 50a, integrates the signal in step S211 and compares the integrated value with a specified value (threshold) in step S212. In step S214, the strobe light emission is stopped or the exposure is terminated (stopping charge accumulation or discharging of the first group of pixels 50a). If it does not exceed, the process waits for the scheduled time to pass in step S213, and FIG.
In step S114, the exposure is completed.

In this embodiment described above, the first group of pixels 50a for acquiring image data and the second group of pixels 50b for acquiring data for exposure control are made independent. However, if the second group of pixels 50b is a so-called non-destructive readable pixel, the amount of the accumulated charges can be confirmed without taking out the accumulated charges. It can be used as a part of data, thereby improving image quality. or,
The integration may be started after the discharge of the charges of the pixels 50b of the second group is completed and after the charges of the pixels 50a of the first group can be output.

In the above-described embodiment, the aperture and the shutter time are determined by measuring the brightness of the subject when the release button is turned on. By determining the timing in advance, it becomes possible to start the exposure immediately when the release button is turned on. For example, the aperture value is set to F8, the shutter speed is set to 1/60, the start of strobe light emission is determined to be at a timing at which full flash emission can be performed within the shutter time immediately before the end of the shutter time, and the first button is turned on by turning on the release button. Exposure by the group of pixels 50a is started, and at the same time, signal reading of the second group of pixels 50b is started, and the integrated value of the output from the second group of pixels 50b is
When a predetermined threshold value is exceeded before a predetermined shutter time (1/60), a stop signal is output from the comparator 7 to forcibly end the exposure of the image sensor. This eliminates the need to determine the aperture and shutter time by measuring the brightness of the subject when the release button is turned on, so that the time lag from when the release button is turned on to the start of exposure is extremely small, and the shutter timing is reduced. You will not miss it. In addition, when the surroundings are bright, the exposure of the image sensor is forcibly terminated before the predetermined shutter time, so that the proper exposure can always be obtained.

As described above, by using the CMOS type image pickup device, the electric charge of an arbitrary pixel can be read out. Therefore, as in the present embodiment, a part of the pixel of the image pickup device 22 is replaced with the exposure control data acquisition data. This eliminates the need for a light-receiving element for measuring the luminance of the field, which is provided in the prior art, thereby reducing costs and increasing the degree of freedom in external design.

Next, another embodiment of the CMOS type image pickup device will be described with reference to FIGS. FIG.
1 is a circuit configuration diagram of a CMOS image sensor according to the present embodiment. As shown in FIG. 15, this CMOS image sensor has a two-dimensional array sensor configuration, in which unit pixels having the above-described structure are arranged in a matrix in the column direction and the row direction.

A vertical shift register 102, which is a circuit for generating a vertical scanning signal (VSCAN), is disposed on the left side of the pixel area. Unit pixels 10 arranged in the row direction for each row
The vertical scanning signal supply lines V1 and V2 that are output one by one from the vertical shift register 102 are connected to the gate of the MOS transistor Qxxa in 0, respectively.

A horizontal shift register 103, which is a circuit for generating a horizontal scanning signal (HSCAN), is arranged below the pixel area. Unit pixels 10 arranged in the column direction for each column
The source of the MOS transistor Qxxa in 0 is connected to different vertical output lines H1 and H2 for each column. Each of the vertical output lines H1 and H2 is a switch M which is different for each column.
The drains of the OS transistors Q01 and Q02 are connected one by one. The gates of the switches Q01 and Q02 are connected to a horizontal shift register 103 which is a circuit for generating a horizontal scanning signal (HSCAN).

A timing generator 101, which is a circuit for generating a shutter signal (VSHT) and a drain voltage (VDD), is arranged on the right side of the image area. Drain voltage supply lines from a timing generator 101, which is a drain voltage (VDD) generation circuit, are connected to drains of MOS transistors in all the two-dimensionally arranged unit pixels 100. further,
MOS in all unit pixels 100 arranged two-dimensionally
A shutter signal supply line from a timing generator 101 which is a circuit for generating a shutter signal (VSHT) is connected to a gate of the transistor.

The sources of the switches Q01 and Q02 are connected to an amplifier 105 through a common constant current source 104, and the output of the amplifier is connected to an output 106. That is, the source of the MOS transistor Qxxb in each unit pixel 100 is connected to the transistors Qxxa and Q01.
, And Q02 to the constant current source 104 to form a pixel-based source follower circuit. Therefore, each MOS
The potential difference between the gate and the source and the potential difference between the bulk and the source of the transistor Qxxb are determined by the connected constant current source (load circuit) 104.

The MOS of each unit pixel is sequentially turned on in response to the vertical scanning signal (VSCAN) and the horizontal scanning signal (HSCAN).
By driving the transistor Qxxb, a video signal (Vout) proportional to the amount of incident light is read. As described above,
Since the unit pixel 100 includes the light receiving diode Dxx and the MOS transistors Qxxb and Qxxa, the pixel portion can be created by using the CMOS technology. Therefore, the pixel portion can be formed on the same semiconductor substrate as the peripheral circuits such as the scanning circuits 101 to 103 and the constant current source 104.

The feature of this element structure is that exposure can be started and ended for all pixels at the same time as in a progressive scan type CCD image pickup element. This is effective when performing accurate exposure control using a light source such as a strobe that emits light only for a short time. In a normal CMOS type image pickup device, reading is performed sequentially one pixel at a time or one line at a time. In this case, there is no problem in ordinary exposure, but when performing exposure by short-time light emission such as strobe light, exposure conditions are limited. That is, light emission must be started while all pixels are performing exposure, and light emission must be terminated. Exposure cannot be terminated by stopping the transfer of charges as in the case of this element.

FIG. 16 shows a case where the sensor of FIG.
9 is a timing chart of each input signal for operating the CMOS image sensor according to the present embodiment in relation to an example in which is used as a second group of pixels. Using a p-type well region,
In addition, it is applied when the optical signal detection transistor Qxxb is an nMOS. The element operation can be repeatedly performed in the order of a sweeping period (initialization), an accumulation period (exposure period), a reading period, a sweeping period (initialization), and so on.

The operation of the above configuration will be described in detail.
There are four voltage values: 0 V, VL (for example, about 1 V), VM (for example, about 3 V), and VH (for example, about 5 V).
In the sweeping period, VH is added to VDD and VSH (t
0). This makes it possible to sweep out charges accumulated in the carrier pocket below the gate of the photodiode Dxx and the MOS transistor Qxxb. After the initialization is completed, VDD is set to VM and VSH is set to VL (t1).
As a result, charges are generated in accordance with the amount of light incident on the photodiode, and the generated charges flow into a carrier pocket formed below the gate of the MOS transistor. The exposure is started from here. The strobe light is emitted in the latter half of the exposure period (t3). At time t2 slightly before time t3, I
11, reading of signals from D11 is started. Using H1, a signal is read from D11 at regular time intervals and integrated. When the integrated value reaches a certain threshold, that is, when the amount of light emission of the strobe light reaches an appropriate value, the exposure is terminated. At this time, this is realized by changing VSH from VL to VM (t4). As a result, during the exposure period, the MOS transistor Qxxb
The flow of charges flowing into the carrier pocket below the gate of the gate stops, and the exposure ends. Thereafter, reading is started by operating the horizontal shift register and the vertical shift register. For example, H1 and V1 are each set to 0V
, The signal from Q11b can be read. Similarly, signals of all pixels can be read out by a combination of Hx and Vx. After reading out all the signals, VDD and VSH are set to VH again to perform initialization to prepare for the next exposure. After a certain period of time, or after the strobe light emission ends, a signal from each pixel is read. At this time, since the signal from the pixel including D11 has already been read, little charge remains. The above example uses a four-pixel sensor, and uses one pixel as a light receiving element. This is basically the same even if the number of pixels increases. However, since there are a plurality of pixels in the second group, an address is set so that the read transistor of each pixel is turned on so that signals from these pixels can be read simultaneously.
The read signals are added and read. It is also conceivable that the output signal after the addition becomes too large and exceeds the dynamic range of the output amplifier. In this case, it is possible to read out a signal for one screen by dividing the second group of pixels one by one or several pixels, not all at the same time, but by increasing the clock for reading. . The output signals are externally added and integrated. The basic structure of the above-mentioned CMOS image sensor is disclosed in, for example, JP-A-11-195778, and will not be described in detail below.

FIG. 17A is a schematic configuration diagram of an electronic still camera according to another embodiment, and FIG.
3 is a diagram of the image sensor 22 viewed from the subject side. This embodiment mainly differs from the embodiment shown in FIG. 9 only in the positions of the pixels of the second group, and thus the description of the same points will be omitted.

In FIG. 17, an image pickup section 50 having only a first group of pixels (not shown) is arranged on a substrate 22a.
Below this, an aggregate of the pixels 50b of the second group is arranged. The signals of the pixels 50b of the second group are output to the comparator 7, as in the embodiment of FIG. At this time, the second group of pixels may be one pixel.

Further, in the present embodiment, a half mirror 60 is provided between the photographing lens 21 and the image sensor 22, and reflects a part of the light (for example, reflected light) from the subject 3 in the direction perpendicular to the optical axis. Let it. The light from the half mirror 60 is
The light is reflected by the mirror 61 and enters the second group of pixels 50b. Exposure control using the output is the same as in the above-described embodiment, and a description thereof is omitted. According to this embodiment, since the imaging unit 54 can use a general-purpose CMOS imaging device including a wiring for extracting a signal, the cost can be further reduced. Note that the half mirror 60 and the mirror 61
An optical system that guides a part of the light from the subject from the photographing lens 21 toward the imaging unit 54 to the light receiving element 50b is configured.

Although the present invention has been described with reference to the embodiments, it should be understood that the present invention should not be construed as being limited to the above-described embodiments, and that modifications and improvements can be made as appropriate. is there. For example, the present invention can be used not only for strobe light control but also for general exposure control. In addition, the present invention is not limited to an electronic still camera, and can be applied to various imaging apparatuses such as a radiation imaging apparatus.

It is also conceivable to use only the pixels on which the green filter is mounted as the second group of pixels for acquiring exposure control data. Further, it is not necessary to fix the positions of the pixels of the second group. For example, in the case of center-weighted metering, the pixels of the second group are selected from the center pixel of the image pickup unit, and in the case of average photometry, the second group of pixels is selected from the entire image pickup unit. A group of pixels can also be selected.

A terminal for acquiring image data and a terminal for acquiring exposure data may be shared, or a strobe light intensity integration output terminal may be separately provided. When scanning and reading out the signals from the pixels of the second group, the signals can be read out separately for each part. For example, since an important subject is often located at the center, it may be read out from the center, read out by column or row, or read in a spiral. By providing two memories (charge storage units) in one pixel and separately recording the image charge before the flash emission and the image charge after the flash emission, the data before the light emission can be acquired intact. In order to control the strobe light emission time, an appropriate amount of light can be estimated in advance, and the light emission can be performed earlier than the exposure end time.

[0113]

According to the present invention, by reducing the number of necessary parts and the number of adjustment steps, the photographing apparatus and the photographing apparatus capable of photometry or dimming with low cost, few restrictions in design, and small errors are provided. An imaging element to be used can be provided.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram of a CMOS image sensor according to an embodiment.

FIG. 2 is a schematic configuration diagram of an image sensor circuit 20 including the image sensor of FIG.

FIG. 3 is a schematic configuration diagram illustrating an arrangement of pixels in an imaging unit;

FIG. 4 is a wiring diagram for extracting signals when the imaging unit of FIG. 3 is used.

FIG. 5 is a schematic configuration diagram illustrating an arrangement of pixels in an imaging unit according to a modification of the present embodiment.

FIG. 6 is a wiring diagram for extracting a signal when the imaging unit of FIG. 5 is used.

FIG. 7 is a schematic configuration diagram illustrating an array of pixels in an imaging unit according to another modification.

8 is a wiring diagram for extracting a signal when the imaging unit of FIG. 7 is used.

FIG. 9 is a diagram showing a schematic configuration of an electronic still camera which is an example of a photographing apparatus according to the present embodiment.

FIG. 10 is a strobe light emission characteristic diagram.

FIG. 11 is a diagram illustrating strobe light emission characteristics when (subject distance) × (aperture) is small.

FIG. 12 is a diagram illustrating strobe light emission characteristics when (subject distance) × (aperture) is large.

FIG. 13 is a diagram illustrating a photographing control flow according to the present embodiment.

FIG. 14 is a diagram showing a shooting control flow for explaining a modification of the flash exposure control of FIG. 13 in detail.

FIG. 15 is a circuit configuration diagram of a CMOS image sensor according to the present embodiment.

FIG. 16 is a timing chart of the present embodiment.

FIG. 17A is a schematic configuration diagram of an electronic still camera according to another embodiment, and FIG.
FIG. 2 is a diagram of the image sensor 22 viewed from a subject side.

[Explanation of symbols]

 2 Strobe 7 Comparator 22 CMOS image sensor 23 Image sensor control circuit 27 MPU 54 Imager 50a First group of pixels 50b Second group of pixels 51 Timing generator 52 Vertical shift register 53 Horizontal shift register 150b Light receiving element

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 5/335 H04N 5/335 Q 5C065 9/07 A // H04N 9/07 H01L 27/14 A F term (Reference) 2H002 CD05 DB01 DB25 2H053 AD08 4M118 AA07 AA10 AB01 BA14 CA02 DD10 DD12 FA06 FA33 FA42 GC08 5C022 AB01 AB15 AB17 AC52 5C024 AX04 CX54 CX67 CY17 EX12 GY31 GZ42 JX46 5C065 BB08 BB41 DD09 DD15

Claims (32)

[Claims] An imaging device for imaging a subject, comprising: a light emitting device for illuminating a subject; and an imaging device in which a plurality of pixels are two-dimensionally arranged. The first group of pixels of the image sensor is used to convert a subject image into image data without having to wait for the discharge of charges, and the first group of pixels of the image sensor is used to convert the image of the subject into image data. The two groups of pixels are used to detect the amount of light from the subject, and the light emission of the light emitting device is stopped in response to the charge accumulated in the second group of pixels exceeding a threshold. An imaging device characterized by being taken. 2. An imaging device for imaging a subject, comprising: an imaging device in which a plurality of pixels are arranged two-dimensionally, wherein the imaging device has an arbitrary configuration without waiting for discharge of charges from other pixels. The first group of pixels of the imaging device is used to convert a subject image into image data, and the second group of pixels of the imaging device is Used to detect the amount of light, stopping charge accumulation in the first group of pixels in response to the charge accumulated in the second group of pixels exceeding a threshold; and An imaging device, wherein at least one of discharging of electric charges accumulated in a pixel is performed. 3. The photographing apparatus according to claim 1, wherein the image pickup device discharges electric charge from a specific pixel in response to a specific trigger signal. 4. The image data corresponding to the positions of the pixels of the second group is the image data of the first group located around the pixels of the second group.
The photographing apparatus according to claim 1, wherein the photographing apparatus is obtained based on image data of a group of pixels. 5. The apparatus according to claim 1, wherein the second group of pixels is a part of the first group of pixels. 6. The image pickup device according to claim 1, wherein the image pickup device includes a determination unit configured to determine whether or not charges accumulated in the pixels of the second group have exceeded a threshold value. Shooting equipment. 7. The photographing apparatus according to claim 1, wherein the image pickup device has an output terminal for outputting charges accumulated in the second group of pixels to the outside. 8. When there are three or more pixels in the second group,
If the value of the charge stored in one of the pixels is higher than the average value of the charges stored in the other pixels by a predetermined value or more, the charge of the pixel having the higher charge is excluded. The photographing apparatus according to claim 1, wherein the photographing apparatus compares the threshold value with the threshold value. 9. The electric charge accumulated in the second group of pixels,
The photographing apparatus according to claim 1, wherein the photographing apparatus is simultaneously ejected. 10. The imaging apparatus according to claim 1, wherein the electric charges accumulated in the pixels of the second group are discharged in response to a clock. 11. The device according to claim 1, wherein the amount of the electric charge accumulated in the pixels of the second group can be detected without being discharged. Shooting equipment. 12. The apparatus according to claim 1, wherein a trigger signal is sequentially applied to the pixels of the second group, so that accumulated charges are discharged in the order in which the trigger signals are applied. An imaging device according to any one of the above. 13. The pixel according to claim 1, wherein the second group of pixels has at least two charge storage units.
An imaging device according to any one of the above. 14. The photographing apparatus according to claim 1, wherein the pixels of the second group are arranged near a center corresponding to a photographing screen. 15. The photographing apparatus according to claim 1, wherein the electric charges accumulated in the second group of pixels are discharged in order from a pixel on the center side corresponding to a photographing screen. . 16. An image pickup device having a plurality of pixels arranged two-dimensionally, which is used for a photographing device provided with a light emitting device for illuminating a subject, without waiting for discharge of charges from other pixels.
A first group of pixels of the image sensor is used to convert a subject image into image data, and a second group of pixels of the image sensor is separated from a subject. An image pickup device, wherein the light emission of the light emitting device is stopped in response to the charge accumulated in the pixels of the second group exceeding a threshold value. . 17. An imaging device in which a plurality of pixels are arranged two-dimensionally, without waiting for discharge of charges from other pixels.
A first group of pixels of the image sensor is used to convert a subject image into image data, and a second group of pixels of the image sensor is separated from a subject. The charge accumulation in the second group of pixels is stopped when the charge accumulated in the second group of pixels exceeds a threshold value, and the charge accumulation in the first group of pixels is stopped. Wherein at least one of discharging of the electric charge accumulated in the pixel is performed. 18. The imaging device according to claim 16, wherein the imaging device discharges electric charges from a specific pixel in response to a specific trigger signal. 19. The image data corresponding to the positions of the pixels of the second group are obtained based on image data of the pixels of the first group located around the pixels of the second group. An image sensor according to claim 16. 20. The image sensor according to claim 16, wherein the second group of pixels is a part of the first group of pixels. 21. The image pickup device according to claim 16, wherein the image pickup device has a judgment unit for judging whether the electric charge accumulated in the pixels of the second group exceeds a threshold value. Imaging device. 22. The image pickup device according to claim 16, wherein the image pickup device has an output terminal for outputting charges accumulated in the second group of pixels to the outside. 23. When there are three or more pixels in the second group, the value of the charge stored in one of the pixels is higher than the average value of the charges stored in the other pixels by a predetermined value or more. 17. The method according to claim 16, further comprising: excluding a charge of a pixel having a high charge value and comparing the pixel value with the threshold value.
23. The imaging device according to any one of claims to 22. 24. The imaging device according to claim 16, wherein the electric charges accumulated in the second group of pixels are simultaneously discharged. 25. The image sensor according to claim 16, wherein the electric charges accumulated in the second group of pixels are discharged in response to a clock. 26. The apparatus according to claim 16, wherein the amount of the electric charge accumulated in the pixels of the second group can be detected without being discharged. Imaging device. 27. The method according to claim 16, wherein a trigger signal is sequentially applied to the pixels of the second group, so that accumulated charges are discharged in the order in which the trigger signals are applied. An imaging device according to any one of the above. 28. The pixel according to claim 16, wherein the second group of pixels has at least two charge storage units.
8. The imaging device according to any one of 7. 29. The imaging device according to claim 16, wherein the pixels of the second group are arranged near a center corresponding to a shooting screen. 30. The image sensor according to claim 16, wherein the electric charges accumulated in the second group of pixels are discharged in order from a pixel on the center side corresponding to a shooting screen. . 31. A plurality of pixels two-dimensionally arranged, and a light receiving element arranged between the pixels, wherein the light receiving elements are arranged in a line over two or more pixels. An imaging element characterized by the above-mentioned. 32. An image pickup unit comprising a plurality of pixels arranged two-dimensionally, a photographing lens for forming a subject image on the image pickup unit, a light receiving element disposed outside the image pickup unit, An imaging system comprising: an optical system that guides a part of light from the subject toward the imaging unit from the imaging lens to the light receiving element.