JP2004172845A - Imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate the discontinuity of luminance at a switching point of addition readout and non-addition readout when motion pictures are read out by multiple pixels CCD for the addition readout to combine the addition readout/non-addition readout and an electronic zoom. <P>SOLUTION: Digitization is performed by an A/D converter via a GCA from the multiple pixels CCD to pass through a signal processing circuit to perform magnification/shrinkage processes in an electronic zoom circuit. An electronic shutter speed is changed in proportion to the quantity of pixel addition. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an operation of an image pickup apparatus using a multi-pixel image pickup device, which is used for both still image shooting and moving image shooting.
[0002]
[Prior art]
With the miniaturization of semiconductors, image sensors have been miniaturized to fine pixels. For this reason, the number of imaging devices for capturing moving images that use an image sensor with a number of pixels equal to or greater than the number of pixels for recording moving images and that can be used for both still image shooting as well as video shooting using the multiple pixels is increasing. are doing.
[0003]
As will be described with reference to FIG. 4, in each of the examples including this example and the following embodiments, it is assumed that an image sensor having 2160 pixels horizontally and 1440 lines vertically is used as shown in FIG.
[0004]
In FIG. 4, reference numeral 400 denotes a lens for imaging; 401, a diaphragm device for controlling the amount of light passing through the lens 400; 402, a CCD image sensor for converting a formed optical image into an electric signal; A gain control amplifier that can be changed as needed; 404, an A / D converter for converting an analog signal into a digital signal; 405, a signal processing circuit for converting an imaging signal into data for recording; and 407, an operation timing signal to each unit. A timing generator 408 for supply is a controller for controlling each of them, and a reference numeral 409 is a reduction processing circuit for converting the image size of the input image signal.
[0005]
The optical image that has passed through the lens 400 and the aperture 401 is converted into an electric signal by the CCD image sensor 402. An image signal obtained from the CCD image sensor 402 is pre-processed in an analog manner by a gain control amplifier 403, sampled by an A / D converter 404, processed into a recorded image signal by a signal processing circuit 405, and then recorded in a moving image recording format. Is recorded on the recording medium via the reduction processing circuit 409 so that the number of pixels conforms to the above. On the other hand, when a still image is recorded, it is sent to the recording medium with the same number of pixels. Control of each unit is performed by a control signal from the controller 408, and the timing generator 407 supplies an appropriate timing signal to each unit based on the control signal.
[0006]
At this time, in order to record a moving image, signals from necessary pixels must be read at a frame rate (about 1/60 second in NTSC). In such a case, signals are read from all of the multi-pixel image sensors. If driven, a very high-speed read operation clock is generated, which causes problems such as a reduction in the charge transfer efficiency of the image sensor.
[0007]
When the image sensor having 2160 pixels in the horizontal direction and 1440 lines in the vertical direction in the present example is read out in 60 frames, the readout speed becomes 2160 × 1440 × 60 = 187 MHz, and the transfer efficiency of the charge of the image sensor is significantly reduced. I will. Since the frame rate is not restricted when capturing a still image, the reading speed can be reduced to a sufficient speed.
[0008]
However, since the number of pixels to be recorded is originally smaller than all the pixels of a multi-pixel element, in an ordinary imaging device using a multi-pixel element, only pixel signals necessary for a moving image are selected from among the multi-pixel imaging elements. In many cases, the operation and readout can be performed at the same speed as that for driving an image pickup device having a normal number of pixels by cutting out and selectively reading out.
[0009]
In this case, as shown in FIG. 6, at the time of photographing a still image, the image sensor is driven so as to read out all pixels as shown in FIG. 6A). At this time, the driving is performed at a sufficiently readable speed since the frame rate is not restricted. On the other hand, at the time of capturing a moving image, by reading out only the lines necessary for the recording format from the central portion of the image sensor as shown in FIG. 6B), the reading can be sufficiently performed without reducing the transfer efficiency.
[0010]
However, in this method, as can be seen from FIG. 6, the angle of view of an image shot through a lens having the same focal length differs greatly between a still image and a moving image.
[0011]
Therefore, there is known a method for solving the above-mentioned problem by adding a plurality of pixels vertically and reading the same when capturing a moving image.
[0012]
This will be described with reference to FIG. 7. In the case of an image pickup device having 1440 vertical lines, three lines of the vertical transfer CCD are added on the vertical transfer CCD, and are read vertically as an addition signal of three lines. Since the number is relatively 480 lines and the vertical transfer speed is only required to be 1/3, the transfer of charges can be performed without lowering the transfer efficiency even when reading in full frame. Things.
[0013]
The circuit configuration at this time is as shown in FIG. The function of each number is the same as in FIG.
[0014]
Further, by using this method and adding an electronic zoom circuit 906 for enlarging or reducing the signal obtained from the signal processing circuit 905 as in the circuit in FIG. 9, three lines are added as shown in FIG. A method of reading from a screen, a method of adding two lines, and cutting out and reading out a line of twice the number of recording lines (480 × 2 = 960 lines), or a method of adding the number of recording lines without performing line addition ( A system has been devised which switches between a method of cutting out and reading out (480 lines) and combining the electronic zoom circuit 906 with the electronic zoom circuit 906, thereby enabling high-magnification electronic zoom with little image deterioration.
[0015]
The operation of the controller for setting the electronic zoom circuit at this time is as shown in FIG. At the time of normal photographing, the setting of the electronic zoom magnification is 1, the addition of vertical lines at that time is 3 lines, and the magnification of the electronic zoom circuit 906 is 1. When the electronic zoom is operated, the electronic zoom magnification setting is sequentially substituted for the magnification of the subsequent electronic zoom circuit 906 using the signal of the three-line addition while the electronic zoom magnification setting is from 1 to 1.5. And expand.
[0016]
Further enlargement was continued, and when the electronic zoom magnification setting reached 1.5 times, the addition of vertical lines was set to two-line addition, and the electronic zoom magnification setting of the electronic zoom circuit 906 was divided by 1.5. Substituting things.
[0017]
Further enlargement is continued, and when the electronic zoom magnification setting reaches three times, the addition of vertical lines is stopped and one line is read, and the value obtained by dividing the electronic zoom magnification setting by 3 into the magnification setting of the electronic zoom circuit 906 is substituted. I will do it.
[0018]
[Problems to be solved by the invention]
However, in the electronic zoom operation, the case of adding three lines, the case of adding two lines, and the case of performing only one line without adding, naturally, “corresponding to the charge of three pixels” “ There is a large difference between the signal charge amount for two pixels and the signal charge amount for one pixel, which is equivalent to the charge for one pixel.
[0019]
Therefore, during the electronic zoom, the brightness of the screen changes at the time of switching the number of added lines, resulting in an unnatural screen. Even if the aperture 900 for exposure control is changed to prevent this, the following speed of the aperture cannot be so high, so that the brightness of the screen is discontinuous for a certain period.
[0020]
[Means for Solving the Problems]
In the present invention, in view of the above problem, an electronic shutter is controlled in accordance with the switching timing of the number of addition lines, so that the amount of charge per pixel read out is kept constant.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention is shown in FIG.
[0022]
In FIG. 1, reference numeral 100 denotes a lens for imaging; 101, a diaphragm device for controlling the amount of light passing through the lens 400; 102, a CCD image pickup device for converting a formed optical image into an electric signal; A gain control amplifier which can be changed as needed; 104, an A / D converter for converting an analog signal into a digital signal; 105, a signal processing circuit for converting an imaging signal into data for recording; An electronic zoom circuit 107 for enlarging or reducing the received signal, a timing generator 107 for supplying an operation timing signal to each unit, and a controller 108 for controlling each of them.
[0023]
The optical image that has passed through the lens 100 and the diaphragm 101 is converted into an electric signal by the CCD image sensor 102. An image signal obtained from the CCD image sensor 102 is pre-processed in an analog manner by a gain control amplifier 103, sampled by an A / D converter 104, processed into a recorded image signal by a signal processing circuit 105, and then electronically zoomed when shooting a moving image. After being subjected to timely enlargement / reduction processing by the circuit 106, the image data is recorded on a recording medium. On the other hand, when a still image is recorded, the image is sent to the recording medium with the same number of pixels. The control of each unit is performed by a control signal from the controller 108, and the timing generator 107 supplies an appropriate timing signal to each unit based on the control signal.
[0024]
FIG. 2 shows the operation of the controller 108 in the embodiment of the present invention. At the time of normal photographing, the setting of the electronic zoom magnification is 1 ×, the addition of vertical lines of the CCD image sensor 102 at that time is 3 lines, the electronic shutter speed is 1/180, and the magnification of the electronic zoom circuit 106 is 1 ×. Become.
[0025]
When the electronic zoom is operated, the electronic zoom magnification is sequentially set to the magnification of the subsequent electronic zoom circuit 106 using the signal of the three-line addition while the electronic zoom magnification is set between 1 and 1.5. Substitute and expand.
[0026]
Further enlargement is continued, and when the electronic zoom magnification setting reaches 1.5 times, two vertical lines of the CCD image sensor 102 are added, the electronic shutter speed is set to 1/120, and the magnification setting of the electronic zoom circuit is performed. Is substituted by the value obtained by dividing the electronic zoom magnification setting by 1.5.
[0027]
Further enlargement is continued, and when the electronic zoom magnification setting reaches three times, the addition of vertical lines of the CCD image sensor 102 is stopped and non-addition reading is performed, the electronic shutter speed is set to 1/60, and the magnification setting of the electronic zoom circuit is performed. Is substituted by the value obtained by dividing the electronic zoom magnification setting by 3.
[0028]
[Other Examples]
7 shows a second embodiment of the present invention. The present invention has the same configuration as FIG. 1 of the first embodiment and the conventional example, but the operation of the controller 108 for setting the electronic zoom circuit 106 is as shown in FIG.
[0029]
At the time of normal photographing, the setting of the electronic zoom magnification is 1, the addition of vertical lines of the CCD image sensor 102 at that time is 3 lines, the electronic shutter speed is 1/90, the gain of the gain control amplifier 103 is 1, and The magnification of the electronic zoom circuit 106 is 1.
[0030]
When the electronic zoom is operated, the electronic zoom magnification is sequentially set to the magnification of the subsequent electronic zoom circuit 106 using the signal of the three-line addition while the electronic zoom magnification is set between 1 and 1.5. Substitute and expand.
[0031]
Further enlargement is continued, and when the electronic zoom magnification setting reaches 1.5 times, two vertical lines of the CCD image sensor 102 are added, the electronic shutter speed is 1/60, and the amplification factor of the gain control amplifier 103. Is set to 1, and the value obtained by dividing the electronic zoom magnification setting by 1.5 in the electronic zoom circuit 106 is substituted.
[0032]
When the electronic zoom magnification setting reaches three times, addition of vertical lines of the CCD image sensor 102 is stopped and non-additional reading is performed. The electronic shutter speed is 1/60, and the gain of the gain control amplifier 103 is set. Is set to 2 times, and the value obtained by dividing the electronic zoom magnification setting by 3 in the electronic zoom circuit 106 is substituted.
[0033]
【The invention's effect】
According to the present invention, in a device that performs vertical line pixel addition, reads a signal from a pixel of the entire screen, and records a moving image, switching of the number of vertical line pixel additions and electronic zoom together provide high image quality. In a configuration in which the electronic zoom is obtained, the amount of charge read out at the time of switching the number of additions becomes constant, so that discontinuity does not occur in the brightness of the obtained screen.
[Brief description of the drawings]
FIG. 1 is a configuration of an embodiment of the present invention.
FIG. 2 shows the operation of the controller according to the first embodiment of the present invention shown in FIG. 1;
FIG. 3 shows the operation of the controller according to the second embodiment of FIG. 1 of the present invention.
FIG. 4 is a configuration diagram of a conventional example.
FIG. 5 is an example of an image sensor used in each example of the present invention and the conventional invention.
FIG. 6 shows an example of imaging in FIG. 4 of a conventional example.
FIG. 7 shows an example of pixel addition in an image sensor in a conventional example.
FIG. 8 is a configuration diagram of a conventional example.
FIG. 9 is a configuration diagram of a conventional example.
FIG. 10 shows the operation of a conventional example of electronic zoom.
11 shows the operation of the controller of FIG. 9 in a conventional example.
[Explanation of symbols]
Reference Signs List 100 lens 101 aperture device 102 CCD image sensor 103 gain control amplifier 104 A / D converter 105 signal processing circuit 106 electronic zoom circuit 107 timing generator 108 controller 400 lens 401 aperture device 402 CCD image sensor 403 gain control amplifier 404 A / D converter 405 Signal processing circuit 407 Timing generator 408 Controller 409 Reduction processing circuit 800 Lens 801 Aperture device 802 CCD imaging device 803 Gain control amplifier 804 A / D converter 805 Signal processing circuit 807 Timing generator 808 Controller 900 Lens 901 Aperture device 902 CCD imaging device 903 Gain Control amplifier 904 A / D converter 905 Signal processing circuit 90 Electronic zoom circuit 907 timing generator 908 controller

Claims (2)

It has a multi-pixel image sensor with more pixels than normal moving image recording pixels, uses that image sensor for both still image and moving image shooting, and cuts out a part of all image pixels when shooting a moving image A method and an imaging system having a structure in which pixels of an image sensor are vertically added and read out by adding a plurality of pixels, so that signals of all pixels can be read out without increasing the readout speed. An image pickup device having a function of suppressing image deterioration by appropriately switching between clipping and vertical addition, and in the image pickup device, when vertically adding and reading out, the electronic device of the image sensor according to the number of pixels to be added. An imaging apparatus characterized in that a signal charge obtained from an imaging element to a signal processing circuit is kept constant by changing a shutter. It has a multi-pixel image sensor with more pixels than normal moving image recording pixels, uses that image sensor for both still image and moving image shooting, and cuts out a part of all image pixels when shooting a moving image A method and an imaging system having a structure in which pixels of an image sensor are vertically added and read out by adding a plurality of pixels, so that signals of all pixels can be read out without increasing the readout speed. An image pickup device having a function of suppressing image deterioration by appropriately switching between clipping and vertical addition, and in the image pickup device, when vertically adding and reading out, an image pickup device according to the number of pixels to be added vertically The amount of signal charge obtained from the image sensor to the signal processing circuit is kept constant by changing the electronic shutter and the variable gain amplifier together. Apparatus.

Images