JP5402329B2 - Imaging unit, electronic camera - Google Patents

Description

  The present invention relates to an imaging unit and an electronic camera equipped with the imaging unit.

  An imaging device in which focus detection pixel arrays are arranged in a limited partial region in a two-dimensional array of imaging pixels and an imaging device using the imaging device are known (for example, see Patent Document 1). . In an imaging apparatus using this type of imaging device, an image signal at a focus detection pixel position is obtained by interpolation based on an image signal output from an imaging pixel around the focus detection pixel, and the focus detection pixel position is obtained. The loss of the image signal is eliminated. Then, an image or video is generated by outputting the interpolated image signal from the image sensor to the CPU and performing signal processing.

JP 2007-279312 A

  In the conventional technique described above, the interpolated image signal (imaging signal) is output from the image sensor to the CPU as it is. Therefore, as the number of pixels of the image sensor increases, the information amount of the image signal output from the image sensor increases. Increase. By the way, in recent digital cameras, it has become possible to perform moving image shooting in addition to still image shooting. In moving image shooting, it is necessary to output the image signal from the image sensor at every predetermined frame rate. Therefore, if the information amount of the image signal increases as the number of pixels of the image sensor increases, the capacity of the signal transmission path is increased accordingly. Must be bigger. However, it may be difficult to increase the capacity of the signal transmission path due to the arrangement of components in the camera and wiring restrictions.

  In addition, in order to solve the above-described problems, the image sensor outputs the image by skipping pixels at a predetermined rate or by internally adding and reading signals from a plurality of pixels. The amount of information of the imaging signal can also be reduced. However, if such skipping or internal addition is performed, there arises a problem that the image quality of the image signal output from the image sensor is greatly deteriorated. Further, since it is necessary to determine a pixel to be skipped or subjected to internal addition in accordance with the arrangement of the focus detection pixels, there arises a problem that the circuit configuration of the image sensor becomes complicated.

An imaging unit according to the present invention is an electronic device having a main signal processing circuit that performs signal processing for generating an image or video based on an imaging signal obtained by imaging a subject image with a light beam incident through an imaging optical system. A plurality of imaging pixels mounted in a camera and arranged two-dimensionally, and a plurality of focus detection pixels mixed in the imaging pixels and arranged one-dimensionally or two-dimensionally. Outputs an imaging signal to represent the subject image according to the received light amount of the light beam and detects the focus adjustment state of the photographic optical system according to the received light amount of the light beam at the focus detection pixel by the pupil division type phase difference detection method an imaging element that outputs a focus detection signal for, after reduction processing of information amount with respect to the imaging signal output from the imaging device, the sub-signal processing times for outputting a signal after the reduction processing in the main signal processing circuit When, with the imaging as a sub-signal processing circuit reduction process, to separate the focus detection signal from the image signal corresponding to the sequence position of the focus detection pixels in the image sensor, corresponding to a sequence position of the focus detection pixel Processing to generate a still image pickup signal after performing interpolation processing to interpolate the signal, processing to generate a moving image pickup signal by performing resolution conversion processing of the still image pickup signal, and gradation conversion processing from the moving image pickup signal The process of generating the live view display signal is selectively performed .
An electronic camera according to the present invention is a signal for generating an image or a video based on various imaging signals after reducing the amount of information of the imaging signal output from the imaging unit and the sub-signal processing circuit of the imaging unit. And a main signal processing circuit for performing processing.

  According to the present invention, it is possible to obtain an image pickup signal with high image quality while suppressing the information amount of the image pickup signal output from the image pickup unit to the main signal processing circuit without complicating the circuit configuration.

It is a block diagram of the digital camera of one embodiment. It is a partial front view of a solid-state image sensor. FIG. 6 is a layout diagram of focus detection areas on a shooting screen. It is a block diagram of a subsignal processing circuit.

  FIG. 1 is a diagram illustrating a configuration of a digital camera according to an embodiment. In FIG. 1, a lens barrel 2 is detachably attached to a camera body 1. The lens barrel 2 is provided with a photographic lens 3, a focusing lens driving device 4, a diaphragm 5 and the like that constitute a photographic optical system. The taking lens 3 includes a focusing lens for performing focus adjustment. The focusing lens is driven by the focusing lens driving device 4. On the other hand, the camera body 1 is provided with an imaging unit 7, a main signal processing circuit 10, a control device 11, a monitor 12, a release button 19, and the like.

  A light beam from a subject incident on the camera body 1 via the photographing lens 3 is guided to the imaging unit 7. Note that a known optical viewfinder including an eyepiece lens, a viewfinder eyepiece window, and the like may be provided on the upper portion of the camera body 1. The photographer can visually recognize the subject image captured by the imaging unit 7 on the monitor 12.

  The imaging unit 7 includes an imaging element 8 and a sub signal processing circuit 9. The imaging element 8 has a plurality of imaging pixels arranged in a two-dimensional manner and a plurality of focus detection pixels arranged in a one-dimensional manner mixed with the imaging pixels.

  FIG. 2 is a front view showing a focus detection pixel array portion of the image sensor 8. In the imaging element 8, imaging pixels 310 corresponding to any of R, G, or B are arranged in a two-dimensional manner according to the Bayer arrangement. In the arrangement of the imaging pixels 310, focus detection pixels 313 and 314 each having a left semicircular shape and a right semicircular photoelectric conversion unit are alternately arranged in a straight line in the horizontal direction. The arrangement of the focus detection pixels 313 and 314 is provided corresponding to the focus detection area 101 set on the photographing screen 100 shown in FIG. Note that the shape and the number of focus detection pixels or the position and number of focus detection areas are not limited to this embodiment. For example, the focus detection pixels may be arranged linearly in the horizontal direction, or may be arranged in a planar shape, that is, in a two-dimensional manner.

  The image sensor 8 receives a light beam from the subject through the photographing lens 3 to output an image signal in accordance with the amount of light received in the image pickup pixel 310 and in accordance with the amount of light received in the focus detection pixels 313 and 314. To output a focus detection signal. The imaging signal is a signal for representing a subject image. On the other hand, the focus detection signal is a signal for detecting the focus adjustment state of the photographing lens 3 by the pupil division type phase difference detection method. As described above, since the focus detection pixels 313 and 314 have the left semicircular and right semicircular photoelectric conversion units, respectively, the light beams that have passed through different pupil positions of the photographing lens 3 are received. By comparing the position of the image corresponding to the focus detection signal from the focus detection pixel 313 and the position of the image corresponding to the focus detection signal from the focus detection pixel 314, according to the pupil division type phase difference detection method, The defocus amount of the photographing lens 3 can be obtained by detecting the image shift amount with respect to the pair of images. The imaging signal and focus detection signal output from the imaging element 8 are input to the sub signal processing circuit 9.

  The sub signal processing circuit 9 performs various kinds of signal processing as will be described later on the imaging signal and the focus detection signal input from the imaging element 8, and outputs the processed signal to the main signal processing circuit 10. By the signal processing performed by the sub signal processing circuit 9, an appropriate signal can be output from the imaging unit 7 to the main signal processing circuit 10 according to the operation state of the camera body 1.

  FIG. 4 shows the configuration of the sub signal processing circuit 9. The sub signal processing circuit 9 includes a focus detection pixel separation circuit 91, an interpolation circuit 92, a resolution conversion circuit 93, a gradation conversion circuit 94, and a signal selection circuit 95.

  The focus detection pixel separation circuit 91 performs signal separation processing for separating the imaging signal input from the imaging element 8 and the focus detection signal. The separated imaging signal is output to the interpolation circuit 92, and the focus detection signal is output to the signal selection circuit 95.

  The interpolation circuit 92 performs an interpolation process for interpolating the imaging signal output from the focus detection pixel separation circuit 91. In this interpolation processing, the image pickup signal is interpolated corresponding to the array positions of the focus detection pixels 313 and 314 in the image pickup device 8. That is, since the imaging signal is not output from the array position of the focus detection pixels 313 and 314 in the image sensor 8, the image signal before the interpolation process lacks a signal corresponding to this array position. Therefore, the imaging signal corresponding to the array position of the focus detection pixels 313 and 314 is interpolated based on the imaging signals from the surrounding imaging pixels 310 to compensate for the lack of imaging signals. The image pickup signal subjected to the interpolation processing by the interpolation circuit 92 is output to the resolution conversion circuit 93 and also output to the signal selection circuit 95 as a still image pickup signal.

  The resolution conversion circuit 93 performs resolution conversion processing for reducing the resolution of the image pickup signal after interpolation processing output from the interpolation circuit 92. In this resolution conversion process, the resolution of the imaging signal after the interpolation process is converted to a resolution suitable for moving image shooting. For example, when the resolution of the image signal after the interpolation processing is 10 million pixels and full high-definition video shooting is performed based on the image signal output from the image sensor 8, the resolution of the full high-definition, that is, about 2 million (1920 The resolution conversion circuit 93 performs resolution conversion processing so that the resolution of × 1080) pixels is obtained. The frame frequency at this time is, for example, 30 frames / second. The imaging signal subjected to the resolution conversion processing in the resolution conversion circuit 93 is output to the gradation conversion circuit 94 and also output to the signal selection circuit 95 as a moving image imaging signal.

  The gradation conversion circuit 94 performs gradation conversion processing for lowering the gradation of the imaging signal after the resolution conversion processing output from the resolution conversion circuit 93. In this gradation conversion process, the gradation of the imaging signal after the resolution conversion process is converted into a gradation suitable for live view display on the monitor 12. For example, when the gradation of the imaging signal after the resolution conversion process is 12 bits and the gradation of the image that can be displayed on the monitor 12 is 8 bits, the gradation conversion circuit 94 performs a process of reducing the gradation from 12 bits to 8 bits. Done. The imaging signal that has been subjected to the gradation conversion processing in the gradation conversion circuit 94 is output to the signal selection circuit 95 as a live view imaging signal.

  By the resolution conversion process performed by the resolution conversion circuit 93 and / or the gradation conversion process performed by the gradation conversion circuit 94 described above, the information amount of the imaging signal output from the imaging element 8 is reduced in the sub-signal processing circuit 9. . By reducing the information amount of the imaging signal in this way, the capacity of the signal transmission path from the imaging unit 7 to the main signal processing circuit 10 can be reduced without complicating the circuit configuration in the camera body 1.

  The signal selection circuit 95 selects any one of the signals output from the focus detection pixel separation circuit 91, the interpolation circuit 92, the resolution conversion circuit 93, and the gradation conversion circuit 94 according to the operation state of the camera body 1. The selected signal is output to the main signal processing circuit 10. That is, when the focus adjustment state of the photographic lens 3 is detected by the pupil division type phase difference detection method, the focus detection signal from the focus detection pixel separation circuit 91 is selected and output to the main signal processing circuit 10. When shooting a still image, the still image pickup signal from the interpolation circuit 92 is selected, and when shooting a moving image, the moving image pickup signal from the resolution conversion circuit 93 is selected and output to the main signal processing circuit 10. Further, when performing live view display, the live view imaging signal from the gradation conversion circuit 94 is selected and output to the main signal processing circuit 10. These signal selection instructions are given from the control device 11 to the sub-signal processing circuit 9.

  By selecting the output signal as described above in the signal selection circuit 95, the information amount of the imaging signal output from the imaging unit 7 to the main signal processing circuit 10 is kept low, and each application (still image / moving image / It is possible to obtain an imaging signal with high image quality according to (live view). That is, during still image shooting, a high-resolution still image pickup signal is output from the image pickup unit 7 at a low speed, so that it can be output even with a low-capacity signal transmission path. On the other hand, at the time of video shooting and live view display, the amount of information is reduced by resolution conversion processing and gradation conversion processing, and each operation is performed while suppressing deterioration of image quality compared to conventional pixel signal skipping and internal addition. It is possible to output an imaging signal having a necessary amount of information at high speed.

  In the imaging unit 7 described above, the imaging device 8 and the sub signal processing circuit 9 are arranged close to each other so that a large amount of information can be transferred between the imaging device 8 and the sub signal processing circuit 9 at high speed. It is preferred that At this time, the sub-signal processing circuit 9 can be downsized by adopting a configuration limited to each of the above circuits. Alternatively, the imaging unit 7 may be configured by an MCM (Multi Chip Module) in which the imaging element 8 and the sub-signal processing circuit 9 are each formed as a bare chip and mounted on a single substrate.

  The main signal processing circuit 10 performs various types of signal processing according to the operation status of the camera body 1 based on the above-described signals output from the imaging unit 7. For example, during still image shooting, signal processing for generating an image to be recorded on a recording medium (not shown) is performed based on a still image pickup signal output from the image pickup unit 7. On the other hand, at the time of moving image shooting, signal processing for generating a video to be recorded on a recording medium (not shown) is performed based on the moving image imaging signal output from the imaging unit 7. Further, during live view display, signal processing for generating video for live view display on the monitor 12 is performed based on the live view imaging signal output from the imaging unit 7. These images or videos generated by the signal processing performed by the main signal processing circuit 10 are output to the control device 11. The main signal processing circuit 10 is constituted by, for example, a DSP (Digital Signal Processor) dedicated to image processing.

  The control device 11 includes a CPU, a memory, and the like, and performs various processes and controls according to the operation of the camera body 1. For example, the control device 11 performs a signal selection instruction for the sub-signal processing circuit 9 described above, image and video recording control for a recording medium (not shown), display control for the monitor 12, and the like. Further, the defocus amount of the photographing lens 3 is obtained based on the focus detection signal output from the imaging unit 7 via the main signal processing circuit 10, and the focusing drive control device 4 is controlled according to the obtained defocus amount. Thus, the focus of the photographic lens 3 can be adjusted. In addition to this, various processes necessary for the camera body 1 to operate are executed in the control device 11.

  The monitor 12 is a display device that can display images, characters, symbols, and the like under the control of the control device 11. In this embodiment, an example in which an LCD is used for the monitor 12 is shown. The control device 11 controls the monitor 12 to display a captured image and various types of shooting information on the monitor 12 and to perform live view display. The live view is a function for displaying, on the monitor 12, a subject image continuously captured by the image sensor 8 during non-shooting based on the above-described live view imaging signal output from the sub signal processing circuit 9. . By performing this live view display, the photographer can determine the composition while viewing the monitor image. This live view starts when the photographer turns on a power switch (not shown) provided on the camera body.

According to the embodiment described above, the following operational effects are obtained.
(1) The imaging unit 7 mounted on the camera body 1 has an imaging element 8 and a sub signal processing circuit 9. The imaging element 8 outputs an imaging signal according to the amount of light received by the imaging pixel 310 and outputs a focus detection signal according to the amount of light received by the focus detection pixels 313 and 314. The sub-signal processing circuit 9 performs an interpolation process for interpolating the imaging signal corresponding to the arrangement positions of the focus detection pixels 313 and 314 in the imaging element 8 in order to reduce the information amount of the imaging signal after performing the interpolation process in the interpolation circuit 92. The resolution conversion process and the gradation conversion process are performed in the resolution conversion circuit 93 and the gradation conversion circuit 94, respectively, and the processed signal is output to the main signal processing circuit 10. Since this is done, it is possible to obtain an image pickup signal with high image quality while keeping the information amount of the image pickup signal output from the image pickup unit 7 to the main signal processing circuit 10 low without complicating the circuit configuration in the camera body 1. Can do.

(2) The sub-signal processing circuit 9 separates the imaging signal after the interpolation processing, resolution conversion processing, and gradation conversion processing in the signal selection circuit 95 from the imaging signal by the focus detection pixel separation circuit 91. By selecting and outputting one of the focus detection signals thus obtained, these signals are separately output to the main signal processing circuit 10. Thus, the main signal processing circuit 10 performs signal processing for generating an image or video based on the imaged signal after signal processing, while outputting the focus detection signal to the control device 11 via the main signal processing circuit 10. As a result, the focus of the photographing lens 3 can be adjusted based on the focus detection signal in the control device 11.

(3) The sub-signal processing circuit 9 reduces the amount of information of the image signal by performing resolution conversion processing for reducing the resolution of the image signal in the resolution conversion circuit 93. Further, the gradation conversion circuit 94 performs gradation conversion processing for reducing the gradation of the imaging signal, thereby reducing the information amount of the imaging signal. Therefore, at the time of moving image shooting or live view display, the image pickup unit 7 outputs an image pickup signal having an amount of information necessary for each operation at a high speed while suppressing deterioration in image quality compared to conventional skipping of pixel signals and internal addition. be able to.

  In the embodiment described above, the focus detection signal from the focus detection pixel separation circuit 91, the still image pickup signal from the interpolation circuit 92, the moving image pickup signal from the resolution conversion circuit 93, or the gradation conversion circuit 94. Is selected in response to a signal selection instruction from the control device 11 in the signal selection circuit 95, so that any one of these signals is transmitted from the sub signal processing circuit 9 to the main signal processing circuit. 10 to output. However, the operation of the focus detection pixel separation circuit 91, the interpolation circuit 92, the resolution conversion circuit 93, and the gradation conversion circuit 94 is permitted or prohibited depending on the operation state of the camera body 1 (the circuit does not operate, the signal is The signal output from the sub signal processing circuit 9 to the main signal processing circuit 10 may be switched by passing through the circuit.

  For example, when the focus of the photographic lens 3 is adjusted, the focus detection pixel separation circuit 91 is operated, and the operations of the interpolation circuit 92, the resolution conversion circuit 93, and the gradation conversion circuit 94 are prohibited (the circuit does not operate, the signal Through this circuit). Thereby, in the sub signal processing circuit 9, the operation of the circuit unnecessary for focus adjustment is stopped (the circuit does not operate, the signal passes through this circuit), and only the focus detection signal from the focus detection pixel separation circuit 91 is obtained. Is output. On the other hand, when shooting a still image, the interpolation circuit 92 is operated in addition to the focus detection pixel separation circuit 91 so that the still image pickup signal from the interpolation circuit 92 is output.

  When shooting a moving image, the sub-signal processing circuit 9 operates the resolution conversion circuit 93 in addition to the focus detection pixel separation circuit 91 and the interpolation circuit 92 to output the moving image imaging signal from the resolution conversion circuit 93. To. At this time, the operation of the gradation conversion circuit 94 remains prohibited as described above. That is, when the video obtained by moving image shooting is recorded on the recording medium under the control of the control device 11, the sub-signal processing circuit 9 prohibits the gradation conversion processing by the gradation conversion circuit 94 and is subjected to gradation conversion. A moving image pickup signal that is not present is output to the main signal processing circuit 10.

  When performing live view display, the sub-signal processing circuit 9 further operates the gradation conversion circuit 94 in addition to the focus detection pixel separation circuit 91, the interpolation circuit 92, and the resolution conversion circuit 93. Output live view imaging signals. That is, when the video generated by the main signal processing circuit 10 is displayed in live view on the monitor 12, the sub signal processing circuit 9 performs gradation conversion processing in the gradation conversion circuit 94, and the live view imaging signal after processing is performed. Is output to the main signal processing circuit 10.

  By switching the output signal as described above in the sub signal processing circuit 9, as in the above-described embodiment, an optimum signal is sent from the imaging unit 7 to the main signal processing circuit according to the operation state of the camera body 1. 10 can be output.

1: camera body, 3: photographing lens, 7: imaging unit, 8: imaging device, 9: sub-signal processing circuit, 10: main signal processing circuit, 11: control device, 12: monitor

Claims (3)

An imaging unit mounted on an electronic camera having a main signal processing circuit that performs signal processing for generating an image or video based on an imaging signal obtained by imaging a subject image with a light beam incident through an imaging optical system Because
A plurality of imaging pixels arranged two-dimensionally, and a plurality of focus detection pixels mixed in the imaging pixels and arranged one-dimensionally or two-dimensionally, and the light flux in the imaging pixels An imaging signal for representing the subject image in accordance with the amount of received light, and the focus adjustment state of the photographing optical system in accordance with the amount of received light of the light beam in the focus detection pixel. An image sensor that outputs a focus detection signal for detection by
A sub-signal processing circuit that outputs the signal after the reduction processing to the main signal processing circuit after reducing the amount of information with respect to the imaging signal output from the imaging element;
The sub signal processing circuit is the reduction process,
A focus detection signal is separated from the imaging signal corresponding to the array position of the focus detection pixels in the image sensor, and an interpolation process is performed to interpolate the imaging signal corresponding to the array position of the focus detection pixels. Processing for generating a still image pickup signal later, processing for generating a moving image pickup signal by performing resolution conversion processing of the still image pickup signal, and generating a live view display signal by performing gradation conversion processing from the moving image pickup signal imaging unit for the processing of, wherein selectively be performed. An imaging unit according to claim 1;
A main signal processing circuit for performing signal processing for generating an image or video based on various imaging signals after reducing the amount of information of the imaging signal output from the sub-signal processing circuit of the imaging unit; An electronic camera comprising: An imaging unit according to claim 1;
A main signal processing circuit for performing signal processing for generating an image or video based on various imaging signals after processing to reduce the amount of information of the imaging signal output from the sub-signal processing circuit of the imaging unit;
Recording control means for recording the image or the video generated by the main signal processing circuit on a recording medium;
And a live view display can display means the image generated by the main signal processing circuit,
The sub-signal processing circuit performs the gradation conversion process when the display unit displays the video in live view, and prohibits the gradation conversion process when the recording control unit records the video on the recording medium. An electronic camera characterized by that.

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