JP2016048862A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus which reduces power consumption by stopping using an amplifier that amplifies an imaging signal, in accordance with a reading mode, and a control method for the imaging apparatus.SOLUTION: An imaging device includes: a vertical output line which performs signal reading from a unit pixel including a plurality of photoelectric transducers; the amplifier by which a signal from the vertical output line is amplified and outputted; a filter circuit for limiting a frequency domain of the signal from the vertical output line; and a selection circuit for connecting the vertical output line with any one of the amplifier and the filter circuit. In the imaging device, the imaging signal is read out while reducing power to be consumed at the amplifier by switching between a first reading mode for reading a signal from the unit pixel via the amplifier and a second reading mode for reading a signal from the unit pixel via the filter circuit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an imaging apparatus.

  A CMOS (Complementary Metal-Oxide Semiconductor) image pickup device is known as an image pickup device used for an image pickup apparatus such as a digital still camera or a digital video camera. This CMOS image sensor is provided with a column circuit for each column of pixels two-dimensionally arranged in the row direction and the column direction. Patent Document 1 discloses a CMOS image pickup device that amplifies an image pickup signal using an amplifier circuit connected to a column circuit. With such a circuit configuration, it is possible to obtain an imaging signal with good image quality by reading the imaging signal.

JP 2003-51989

  However, in the configuration disclosed in Patent Document 1, since each column has an amplifier circuit, power is consumed for driving the column. In particular, in recent years, the number of pixels of the image sensor has become enormous, and the number of columns has increased accordingly, so the power consumed by the entire amplifier circuit has increased.

  SUMMARY An advantage of some aspects of the invention is that it provides an imaging apparatus that reduces power consumption in accordance with a mode for reading an imaging signal, and a method for controlling the imaging apparatus.

  In order to achieve the above object, an imaging apparatus of the present invention includes a pixel array unit in which unit pixels each including a plurality of photoelectric conversion elements are arranged in a matrix, a vertical output line for reading signals from the unit pixels, An amplifier that amplifies and outputs a signal from the vertical output line, a filter circuit for limiting a frequency region of a signal from the vertical output line, and either the vertical output line and the amplifier or the filter circuit An image sensor comprising: a selection circuit for connecting to each other; and a connection control means for controlling the selection circuit; and a control circuit for controlling the connection control means to read out an imaging signal from the unit pixel via the amplifier. Control means for switching between one readout mode and a second readout mode for controlling the connection control means to read out an imaging signal from the unit pixel via the filter circuit Characterized in that it has a.

  According to the present invention, it is possible to switch whether an imaging signal from a pixel is read out via a column amplifier or read out via a filter circuit without passing through the column amplifier. Therefore, by reading through the filter circuit, it is possible to obtain imaging signals (image data) with good image quality by reducing the frequency causing noise while reducing the power consumed by the column amplifier.

1 is an equivalent circuit diagram of an image sensor according to an embodiment of the present invention. It is a block diagram which shows the structural example of the imaging device concerning embodiment of this invention. It is a block diagram which shows the structural example of the image pick-up element concerning embodiment of this invention. 3 is a flowchart illustrating an example of driving of the imaging apparatus according to the first embodiment. 6 is a flowchart illustrating an example of driving of an imaging apparatus according to a second embodiment. It is a timing chart which shows the drive timing of the 1st read-out mode concerning the embodiment of the present invention. It is a timing chart which shows the drive timing of the 2nd read-out mode concerning the embodiment of the present invention. It is a block diagram which shows the structural example of the image pick-up element concerning 3rd Embodiment. 10 is a flowchart illustrating an example of driving of an imaging apparatus according to a third embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
A first embodiment of the present invention will be described. FIG. 2 is a block diagram illustrating an example of an imaging apparatus according to the present invention. An imaging apparatus 100 according to the present invention includes a lens 101, an imaging element 102, an analog front end unit (AFE) 103 including an A / D conversion circuit, a digital signal processing unit (DSP) 104, a CPU 105, a display unit 106, a recording medium 107, An image memory 108, an operation unit 109, and a timing generation unit (TG) 110 are included.

  The lens 101 forms an optical image of the subject on the image sensor 100. The image sensor 102 converts the formed optical image into an image signal by photoelectric conversion and outputs the image signal. An imaging signal output from the imaging element 102 is input to the AFE 103.

  The AFE 103 amplifies the input imaging signal and performs A / D conversion processing to generate a digital signal. The DSP 104 receives the digital signal output from the AFE 103 and performs various image processing and compression processing.

  The image memory 108 records image data processed by the DSP 104. The display unit 106 displays various settings to be performed by the user and image data recorded in the image memory 108. The display unit 106 uses, for example, an LCD as a display element. The TG 110 supplies a control signal generated for performing predetermined imaging driving to the imaging device 100.

  The operation unit 109 issues operation commands for various functions and readout modes of the imaging apparatus based on user operations. The CPU 105 controls the image sensor 100, the AFE 103, the DSP 104, and the TG 110 based on various information set by the operation unit 109.

  FIG. 3 is a block diagram illustrating a configuration example of the image sensor 102 according to the present embodiment. The image sensor 102 includes a vertical scanning circuit 200, a pixel 201, a vertical output line 202, a load current source 203, a column circuit 204, column selection switches 205 and 206, an output amplifier 207, reset switches 208 and 209, a horizontal scanning circuit 210, and a horizontal scanning circuit 210. Output lines 211 and 212 are provided.

  In the imaging element 102, a plurality of pixels 201 including photoelectric conversion elements are two-dimensionally arranged in the row direction and the column direction. A specific configuration of the pixel 201 will be described later. The vertical scanning circuit 200 supplies the signals φTXn, φRESn and the signal φSELn to the pixel 201 and controls reading of the signal charges. The load current source 203 drives a source follower 304 in a selected row, which will be described later, via the vertical output line 202. The vertical output line 202 is a signal line that outputs an imaging signal from the pixel 201 for each column.

  The column circuit 204 is connected in common to the plurality of pixels 201 in the corresponding column via the vertical output line 202, and amplifies and records the imaging signal from the pixel 201. The configuration of the column circuit 204 will be described later. The column selection switches 205 and 206 control connection between the output terminal of the column circuit 204 and the horizontal output lines 211 and 212. The horizontal scanning circuit 210 supplies a signal φH to the column selection switches 205 and 206, and sequentially outputs signals from the column circuit 204 to the horizontal output lines 211 and 212.

  The output amplifier 207 outputs the signals of the horizontal output lines 211 and 212 to the outside of the image sensor 102. The reset switches 208 and 209 are ON / OFF controlled by the signal φCHR, and the horizontal output lines 211 and 212 are reset by the reset power source VCHR for each horizontal scanning signal (one signal φH).

  FIG. 1 is an equivalent circuit diagram of the image sensor 102. The pixel 201 includes a photodiode 300, a transfer gate 301, a reset switch 302, a storage capacitor 303, a source follower 304, and a row selection switch 305. The photodiode 300 as a photoelectric conversion element generates and accumulates signal charges corresponding to the irradiated light.

  The transfer gate 301 is ON / OFF controlled by the signal φTXn, and transfers the signal charge generated and stored in the photodiode 300 to the storage capacitor 303. The storage capacitor 303 stores the signal charge transferred by the transfer gate 301. The reset switch 302 is ON / OFF controlled by a signal φRESn, and resets unnecessary signal charges accumulated in the photodiode 301 or the storage capacitor 303.

  The source follower 304 amplifies the signal charge stored in the storage capacitor 303 and converts it into a voltage. The reset switch 302, the storage capacitor 303, and the source follower 304 constitute a floating diffusion amplifier. The row selection switch 305 is ON / OFF controlled by a signal φSELn, and controls the connection between the output of the source follower 304 and the vertical output line 202.

  The column circuit 204 includes a column amplifier selection switch 400, a filter circuit selection switch 401, a clamp capacitor 402, a feedback capacitor 403, a clamp switch 404, a column amplifier power switch 405, a column amplifier 406, a filter circuit 407, transfer gates 411 and 410, and a transfer. Capacitors 413 and 412 are provided. The clamp capacitor 402 clamps a signal from the vertical output line 202.

  The inverting input terminal of the column amplifier 406 is connected to the output terminal of the column amplifier 406 via the feedback capacitor 403. The column amplifier 406 amplifies the output of the clamp capacitor 402. The amplification factor of the column amplifier 406 is determined by the ratio between the clamp capacitor 402 and the feedback capacitor 403. A clamp switch 404 whose ON / OFF is controlled by a signal φCLAMP is connected between the inverting input terminal and the output terminal of the column amplifier 406. A power supply Vref is input to a non-inverting input terminal of the column amplifier 406. A power supply Vamp is input to the drive voltage of the column amplifier 406. The column amplifier power switch 405 is controlled to be turned on / off by a signal φAMPENB, and controls the driving of the column amplifier 406.

  A filter circuit selection switch 402 and a filter circuit 407 are connected between the vertical output line 202 and the output terminal of the column amplifier 406. The filter circuit selection switch 402 is controlled to be turned on / off by a signal φTFIL. The filter circuit 407 includes a filter resistor 408 and a filter capacitor 409. When the filter circuit 407 does not read the signal from the vertical output line 202 via the column amplifier 406, the filter circuit 407 suppresses the change in the frequency band of the signal. When the filter circuit selection switch 402 is turned on, a signal is read through the filter circuit 407.

  The signal amplified by the column amplifier 406 or the signal passing through the filter circuit is stored in the transfer capacitors 413 and 412 via the transfer gates 411 and 410. The signals stored in the transfer capacitors 413 and 412 are output to the horizontal output lines 211 and 212 by turning on the column selection switches 205 and 206 that are controlled to be turned on / off according to the signal φH from the horizontal scanning circuit 210. Is done.

  The output amplifier 207 outputs a difference signal between an imaging signal input from one of the horizontal output lines 211 and 212 and a noise signal input from the other of the horizontal output lines 212 and 211 to the outside of the imaging element 100. To do.

  In the first embodiment, control for switching between the two readout modes is performed in accordance with the ISO sensitivity. Examples of setting the ISO sensitivity are when the user selects from the operation unit 109 or when the imaging apparatus 100 automatically sets the ISO sensitivity.

  When the high ISO sensitivity is selected, the CPU 105 sets the photographing operation of the imaging apparatus 100 to the first readout mode in which the imaging signal is read out via the column amplifier 406. When the low ISO sensitivity is selected, the CPU 105 sets the shooting operation of the imaging apparatus 100 to the second reading mode in which the imaging signal is read without using the column amplifier 406.

FIG. 4 is a flowchart for explaining the imaging operation of the imaging apparatus 100 of the present invention.
In step S601, it is determined whether or not a preparation for photographing is instructed. When S1 instructing the start of shooting preparation is turned on (Yes in step S601), the process proceeds to step S602. When S1 is OFF (No in step S601), the process proceeds to step S601.

  In step S602, it is determined whether or not an instruction to perform shooting is instructed. When S2 instructing execution of shooting is turned on (Yes in step S602), the process proceeds to step S603. When S2 is OFF (No in step S602), it is determined that shooting execution is not instructed, and the process proceeds to step S601.

  In step S603, the set ISO sensitivity is determined. If it is set higher than the predetermined ISO sensitivity (Yes in step S603), the process proceeds to step S604. If it is set lower than the predetermined ISO sensitivity (No in step S603), the process proceeds to step S605.

  In step S604, the drive setting of the imaging apparatus 100 is set to the first readout mode, and the process proceeds to step S606. In step S605, the drive setting of the imaging apparatus 100 is set to the second readout mode, and the process proceeds to step S606.

  In step S606, a signal for one frame is read from the image sensor 102 in the set readout mode, and the process proceeds to step S607. In step S607, it is determined whether or not an instruction to continue shooting is instructed. When S2 is ON (No in step S607), it is determined that an instruction to continue shooting is instructed, and the process proceeds to step S603. When S2 is OFF (Yes in step S607), it is determined that an instruction to continue shooting is not given, and the series of operations is terminated.

  In the first readout mode, control is performed to read out the imaging signal via the column amplifier 406. FIG. 6 is a timing chart showing an example of drive timing of the image sensor 102 in the first readout mode.

  FIG. 6 shows the drive timing in one horizontal period when the imaging signal is read from the pixel 201 included in the imaging element 102. Each signal in the figure is assumed to be in a high (hereinafter referred to as “H”) or low (hereinafter referred to as “L”) state. This is common to the following similar timing charts.

  Hereinafter, a reading operation for the pixel 201 arranged in the n-th row in the plurality of imaging elements 102 arranged two-dimensionally will be described. For convenience of explanation, the “signal φSEL in the nth row” is referred to as “signal φSELn”. The same applies to other signals. Further, “the pixel 201 in the nth row” is appropriately referred to as a pixel 201.

  In the first read mode, the signal φAMPENB becomes “H”, the column amplifier power switch 405 is turned on, and the column amplifier 406 is driven. Further, the signal φTAMP becomes “H”, the column amplifier selection switch 400 is turned ON, and the imaging signal is read out via the column amplifier.

  At time t 1, the signal φSELn becomes “H”, the row selection switch 305 is turned ON, and the circuit of the pixel 201 in the n-th row is connected to the vertical output line 202. At the same time, the signal φRESn becomes “H”, the reset switch 302 is turned ON, and unnecessary charges stored in the storage capacitor 303 are reset.

  At time t2, the signal φRESn becomes “L”, the reset switch 302 is turned off, and the resetting of unnecessary charges is completed. At the same time, the signal φCLAMP is set to “H” and the clamp switch 404 is turned ON.

  At time t3, the signal φCLAMP becomes “L” and the clamp switch 404 is turned OFF. As a result, the noise component generated in the pixel 201 is clamped by the clamp capacitor 402 connected by the vertical output line 202. At the same time, the signal φTN becomes “H”, the transfer gate 411 is turned on, and the noise signal amplified by the column amplifier 406 is transferred to the transfer capacitor 413.

  At time t4, the signal φTN becomes “L”, the transfer gate 411 is turned off, and the transfer of the noise signal in the transfer capacitor 413 is completed. At time t5, the signal φTXn becomes “H”, and the transfer gate 301 is turned ON. As a result, the signal charge accumulated in the photodiode 300 is transferred to the storage capacitor 303. The signal charge of the storage capacitor 303 in the pixel 201 is amplified by the source follower 304, and the signal charge is converted into a voltage and output to the vertical output line 202.

  At time t6, the signal φTXn becomes “L”, the transfer gate 301 is turned off, and the transfer of the signal charge to the storage capacitor 303 is completed. At the same time, the signal φTS becomes “H” and the transfer gate 411 is turned ON. The signal output to the vertical output line 202 is transferred to the transfer capacitor 413 via the clamp capacitor 402 and the column amplifier.

  At time t7, the signal φTS becomes “L”, the transfer gate 411 is turned off, and the transfer of the imaging signal in the transfer capacitor 413 is completed. At time t8, the signal φSELn becomes “L”, the row selection switch 305 is turned OFF, and the readout of the imaging signal from the pixel 201 in the n-th row is completed.

  At time t9, a horizontal scanning period starts for the signal of the pixel 201 in the nth row. Input of the signal φH to the horizontal scanning circuit 210 is started. The horizontal scanning circuit 210 sequentially turns on the column selection switches 205 and 206 in response to the signal φH. When the column selection switches 205 and 206 are turned ON, signals stored in the transfer capacitors 413 and 412 are output to the horizontal output lines 211 and 212, respectively. Then, the output amplifier 207 subtracts the noise signal input to the horizontal output line 211 from the imaging signal input via the horizontal output line 212 and outputs it as an image signal for one row.

  In the second readout mode, control is performed to read out the imaging signal without using the column amplifier 406. FIG. 7 is a timing chart showing an example of drive timing of the image sensor 102 in the second readout mode.

  FIG. 7 shows the drive timing in one horizontal period when the imaging signal is read from the pixel 201 included in the imaging element 102.

  In the second read mode, the signal φAMPENB becomes “L”, the column amplifier power switch 405 is turned off, and the driving of the column amplifier 406 is stopped.

  At time t1, the signal φSELn becomes “H”, the row selection switch 305 is turned ON, and the circuit of the pixel 201 in the n-th row is connected to the vertical output line 202. At the same time, the signal φRESn becomes “H”, the reset switch 302 is turned ON, and unnecessary charges stored in the storage capacitor 303 are reset.

  At time t2, the signal φRESn becomes “L”, the reset switch 302 is turned off, and the resetting of unnecessary charges is completed. At the same time, the signal φCLAMP is set to “H” and the clamp switch 404 is turned ON. At the same time, the signal φTAMP is set to “H” and the column amplifier selection switch 400 is turned ON.

  At time t3, the signal φCLAMP becomes “L” and the clamp switch 404 is turned OFF. The noise component generated in the pixel 201 is clamped by the clamp capacitor 402 connected by the vertical output line 202. At the same time, the signal φTAMP becomes “L”, and the column amplifier selection switch 400 is turned OFF. At the same time, the signal φTFIL becomes “H” and the filter circuit selection switch 402 is turned ON. At the same time, the signal φTS becomes “H”, the transfer gate 411 is turned on, and the noise signal output from the filter circuit 407 is transferred to the transfer capacitor 413.

  At time t4, the signal φTS becomes “L”, the transfer gate 411 is turned off, and the transfer of the noise signal in the transfer capacitor 413 is completed. At time t5, the signal φTXn becomes “H”, and the transfer gate 301 is turned ON. As a result, the signal charge accumulated in the photodiode 300 is transferred to the storage capacitor 303. The signal charge of the storage capacitor 303 in the pixel 201 is amplified by the source follower 304, and the signal charge is converted into a voltage and output to the vertical output line 202.

  At time t6, the signal φTXn becomes “L”, the transfer gate 301 is turned off, and the transfer of the signal charge in the storage capacitor 303 is completed. At the same time, the signal φTN becomes “H” and the transfer gate 411 is turned ON. The signal output to the vertical output line 202 is transferred to the transfer capacitor 413 via the filter circuit selection switch 402 and the filter circuit 407.

  At time t7, the signal φTN becomes “L”, the transfer gate 411 is turned off, and the transfer of the imaging signal in the transfer capacitor 413 is completed. At the same time, the signal φTFIL becomes “L”, and the filter circuit selection switch 402 is turned OFF.

  Since the drive timing after time t8 is the same as the drive timing in the first readout mode described above, description thereof is omitted.

  In the present embodiment, use / non-use of the column amplifier 406 is switched according to the ISO sensitivity setting. With high ISO sensitivity, the readout mode is set to the first readout mode and the column amplifier 406 is not used. For low ISO sensitivity, the readout mode is set to the second readout mode and the column amplifier 406 is used.

  In the second readout mode, control is performed to read out the imaging signal without using the column amplifier 406. Since the column amplifier 406 is not used at low ISO sensitivity, the power consumed by the column amplifier 406 can be reduced. In the second reading mode, since the column amplifier 406 is not used for reading, the necessary gain is applied by a subsequent processing circuit such as the output amplifier 207, the AFE 103, or the DSP 104.

  In the low ISO sensitivity, noise generated in the column amplifier 406 itself through the column amplifier 406 is affected, and the S / N of the imaging signal is deteriorated. Therefore, at low ISO sensitivity, the direction that does not pass through the column amplifier 406 is less affected by noise than the direction that passes through.

  However, since the frequency that causes noise that has been reduced by the column amplifier 406 itself is included in the image pickup signal without passing through the column amplifier 406, the image quality may be deteriorated depending on the frequency characteristics of the output amplifier 207. There is. Therefore, the filter circuit 407 is used to make the frequency band of the imaging signal equal to the frequency band of the imaging signal obtained by using the column amplifier 406. Therefore, in the second readout mode, the frequency that causes noise is reduced by reducing the frequency that causes noise while reducing the power consumed by the column amplifier 406 by passing through the filter circuit 407 provided in the column circuit 204. An imaging signal (image data) can be obtained.

  In the first readout mode, control is performed to read out the imaging signal via the column amplifier 406. This is because if the image signal is amplified by the output amplifier 207 after being influenced by noise generated in the column circuit 204 or later when not passing through the column amplifier 406 at high ISO sensitivity, the S / N is reduced and the image quality deteriorates. Occurs. Thus, although the power consumption cannot be reduced, the influence of noise generated after the column circuit 204 can be reduced by passing through the column amplifier 406, and an imaging signal (image data) with good image quality can be obtained.

<Second Embodiment>
In the present embodiment, control for switching between the two reading modes is performed depending on whether or not image data is recorded on the recording medium 107. A case where the image data is not recorded on the recording medium 107 is, for example, shooting (live view shooting) in which shooting is performed while displaying the image data on the display unit 106. An example of recording image data on the recording medium 107 is moving image shooting.

  A second embodiment of the present invention will be described. In the second embodiment, control is performed to switch between the two reading modes depending on whether image data is recorded on the recording medium 107 or not. That is, the CPU 105 selects the first read mode via the column amplifier 406 when recording image data on the recording medium 107, and does not pass through the column amplifier 406 when not recording image data on the recording medium 107. A second readout mode via the filter circuit 407 is selected. Whether or not to record an image on the recording medium 107 is set from the operation unit 109.

  The drive timing of the image sensor 102 in the first and second readout modes in the present embodiment is the same as the drive timing in the first and second readout modes in the first embodiment described with reference to FIGS. 6 and 7. Therefore, the description is omitted.

  FIG. 5 is a flowchart for explaining the imaging operation of the imaging apparatus 100 of the present invention. The operation from step S701 to step S702 is the same as that from step S601 to S602 in the flowchart of FIG.

  In step S703, it is determined whether or not image data is to be recorded on the recording medium 107. When image data is recorded on the recording medium 107 (Yes in step S703), the process proceeds to step S704. When no image data is recorded on the recording medium 107 (No in step S703), the process proceeds to step S704.

  The imaging operation after step S704 is the same as the imaging operation after step S604 in the flowchart of FIG.

  In the present embodiment, the use / non-use of the column amplifier 406 is switched depending on whether image data is recorded on the recording medium 107. When recording image data on the recording medium 107, the reading mode is set to the first reading mode and the column amplifier 406 is used. When image data is not recorded on the recording medium 107, the reading mode is set to the second reading mode, and the column amplifier 406 is not used.

  In the second readout mode, control is performed to read out the imaging signal without using the column amplifier 406. At this time, since the column amplifier 406 is not used, the power consumed by the column amplifier 406 can be reduced. Here, if the image signal does not pass through the column amplifier 406, a frequency that causes noise that has been reduced by the column amplifier 406 itself is included in the imaging signal. Therefore, depending on the frequency characteristics of the output amplifier 207, the image quality may deteriorate. There is a fear.

  Therefore, in order to make the frequency band of the imaging signal equal to the frequency band of the imaging signal obtained by using the column amplifier 406, the filter circuit 407 is used. Therefore, in the second readout mode, the frequency that causes noise is reduced by reducing the frequency that causes noise while reducing the power consumed by the column amplifier 406 by passing through the filter circuit 407 provided in the column circuit 204. An imaging signal (image data) can be obtained.

  In the first readout mode, control is performed to read out the imaging signal via the column amplifier 406. This is because, when not passing through the column amplifier 406, the S / N is lowered and the image quality is deteriorated when the image pickup signal is amplified by the output amplifier 207 after being influenced by noise generated after the column circuit 204. Thus, although the power consumption cannot be reduced, the influence of noise generated after the column circuit 204 can be reduced by passing through the column amplifier 406, and an imaging signal (image data) with good image quality can be obtained.

<Third Embodiment>
In the present embodiment, a pixel (hereinafter referred to as an imaging pixel) for obtaining an imaging signal (image data) disposed in the imaging element 102 and a pixel for performing focus detection (hereinafter referred to as a focus detection pixel) are used. The control which switches the drive of is performed.

  A third embodiment of the present invention will be described. In the third embodiment, when driving the imaging pixels, the first readout mode via the column amplifier 406 is set. When driving the focus detection pixels, the second readout mode via the filter circuit 407 is set without using the column amplifier 406. As will be described later, the mode is determined in step S903 in the flowchart of FIG.

  FIG. 8 is a block diagram showing the arrangement of imaging pixels and focus detection pixels on the imaging surface. The imaging pixels and focus detection pixels are arranged in rows. An imaging row 500 is a row in which imaging pixels are arranged, and a focus detection row 501 indicates a row in which focus detection pixels are arranged. In the present embodiment, control for switching between driving of the imaging row 500 and the focus detection row 501 is performed. The CPU 105 switches between a first readout mode that passes through the column amplifier 406 and a second readout mode that passes through the filter circuit 407 without using the column amplifier 406 according to the role of the pixels arranged on the imaging surface. .

  The drive timing of the image sensor 102 in the first and second readout modes in the present embodiment is the same as the drive timing in the first and second readout modes in the first embodiment described with reference to FIGS. 6 and 7. Therefore, the description is omitted.

  FIG. 9 is a flowchart for explaining the imaging operation of the present embodiment. The operation from step S901 to step S902 is the same as that from step S601 to S602 in the flowchart of FIG.

  In step S903, shooting is started, and the process proceeds to step S904. In step S904, it is determined whether or not the row selected by the row selection switch 305 is the imaging row 500. If the selected row is the imaging row 500 (Yes in step S904), the process proceeds to step S905. If the selected row is the focus detection row 501 (No in step S904), the process proceeds to step S906.

  In step S905, the drive setting of the imaging row 500 is set to the first readout mode, and the process proceeds to step S907. In step S906, the drive setting of the focus detection row 501 is set to the second readout mode, and the process proceeds to step S907. In step S907, the signal of the selected row is read, and the process proceeds to step S908.

  In step S908, it is determined whether or not the row selected by the row selection switch 305 is the last row. When it is the last line (Yes in step S908), the process proceeds to step S909. When it is not the last line (No in step S908), the process proceeds to step S903.

  In step S909, shooting is ended, and the process proceeds to step S910. In step S910, it is determined whether or not an instruction to continue shooting is instructed. When S2 is ON (No in step S910), it is determined that an instruction to continue shooting is instructed, and the process proceeds to step S903. When S2 is OFF (Yes in step S910), it is determined that an instruction to continue shooting is not given, and the series of operations is terminated.

  In the present embodiment, use / non-use of the column amplifier 406 is switched by driving the imaging pixels and focus detection pixels. When driving the imaging pixels, the readout mode is set to the first readout mode and the column amplifier 406 is used. When driving the focus detection pixels, the readout mode is set to the second readout mode, and the column amplifier 406 is not used.

  In the second readout mode, control is performed to read out signals from the focus detection pixels without using the column amplifier 406. At this time, since the column amplifier 406 is not used, the power consumed by the column amplifier 406 can be reduced.

  Here, since a signal read from the focus detection pixel (hereinafter referred to as a focus detection signal) does not pass through the column amplifier 406, it is affected by noise generated after the column circuit 204. However, the focus detection signal need not have an S / N equivalent to that of the imaging signal, considering that there is sufficient S / N that can perform focus detection. Therefore, in the second reading mode, priority is given to power consumption, and the focus detection signal is read by driving that does not use the column amplifier 406.

  At this time, there is a possibility that the frequency band of the focus detection signal is changed only by not passing through the column amplifier 406. If the frequency band of the focus detection signal changes, the image quality may deteriorate depending on the frequency characteristics of the output amplifier 207. Accordingly, the filter circuit 407 is used to make the frequency band of the focus detection signal equal to the frequency band of the imaging signal obtained by using the column amplifier 406. Therefore, in the second readout mode, the image quality can be improved without changing the frequency band of the imaging signal while reducing the power consumed by the column amplifier 406 by passing through the filter circuit 407 provided in the imaging element 102. An imaging signal (image data) can be obtained.

  In the first readout mode, control is performed to read out the imaging signal via the column amplifier 406. This is because, when not passing through the column amplifier 406, the S / N is lowered and the image quality is deteriorated when the image pickup signal is amplified by the output amplifier 207 after being influenced by noise generated after the column circuit 204. Thus, although the power consumption cannot be reduced, the influence of noise generated after the column circuit 204 can be reduced by passing through the column amplifier 406, and an imaging signal (image data) with good image quality can be obtained.

  In the above embodiment, the focus detection pixels are arranged in units of rows. However, the imaging pixels and the focus detection pixels may be arranged in the same row. At this time, when the column amplifier 406 is not used in the column having the focus detection pixels, the S / N of the imaging signals arranged in the same row may be deteriorated. In this case, the DSP 104 may be configured to correct the signal from the imaging pixel in which the column amplifier 406 is not used.

  As described above, in each of the above embodiments, the power consumption can be reduced by stopping the driving of the column amplifier 406 in accordance with the read mode. Therefore, it is possible to provide an imaging apparatus with reduced power consumption, which is an object of the present invention.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

  For example, in each of the embodiments described above, the filter circuit 407 is a low-pass filter circuit, but may be a filter circuit that matches the frequency band of the imaging signal output from the vertical output line 202. In this case, the filter circuit must not have a circuit configuration that exceeds the power consumption of the column amplifier 406.

201 pixels, 202 vertical output lines, 203 load current sources, 204 column circuits,
205 column selection switch, 206 column selection switch, 207 output amplifier,
211 horizontal output lines, 212 horizontal output lines, 300 photodiodes,
301 transfer gate, 302 reset switch, 303 storage capacity,
304 source follower, 305 row selection switch, 400 column amplifier selection switch,
401 Filter circuit selection switch, 402 Clamp capacitance, 403 Feedback capacitance,
404 Clamp switch, 405 column amplifier power switch, 406 column amplifier,
407 filter circuit, 408 filter resistance, 409 filter capacitance,
410 transfer gate, 411 transfer gate, 412 transfer capacity, 413 transfer capacity

Claims (8)

A pixel array unit in which unit pixels each having a plurality of photoelectric conversion elements are arranged in a matrix; a vertical output line for reading a signal from the unit pixel; and an amplifier for amplifying and outputting a signal from the vertical output line; A filter circuit for limiting a frequency region of a signal from the vertical output line; a selection circuit for connecting the vertical output line to either the amplifier or the filter circuit; and controlling the selection circuit An image pickup device comprising connection control means for
A first readout mode for controlling the connection control means to read out an imaging signal from the unit pixel via the amplifier; and controlling the connection control means from the unit pixel via the filter circuit. An imaging apparatus comprising: control means for switching between a second reading mode for reading an imaging signal. The imaging apparatus according to claim 1, wherein in the second readout mode, driving of the amplifier is stopped.   The imaging apparatus according to claim 1, wherein the control unit switches between the first readout mode and the second readout mode according to imaging sensitivity. The imaging apparatus according to claim 3, wherein the control unit selects a first readout mode when setting high sensitivity. A signal processing unit that generates image data from an output signal from the image sensor; and a recording medium for recording the image data from the signal processing unit; The imaging apparatus according to claim 3, wherein the first readout mode and the second readout mode are switched in response to the change. The imaging apparatus according to claim 5, wherein the control unit selects a first reading mode when recording on the recording medium. In the pixel array unit, a first pixel group and a second pixel group are arranged, and the control unit reads out the signal from the first pixel group in the first readout mode, The image pickup apparatus according to claim 1, wherein when the signal is read from the second pixel group, reading in the second reading mode is controlled. The imaging apparatus according to claim 7, wherein the first pixel group is configured by imaging pixels, and the second pixel group is configured by focus detection pixels.