JP2006109037A - Solid-state imaging device - Google Patents

Abstract

An object of the present invention is to prevent distortion of an image that occurs when a moving object is imaged in a solid-state imaging device using a solid-state imaging device of a focal plane readout system.
A solid-state image pickup device, a solid-state image pickup device 2, a timing generation device 3 and a storage device 4 are provided to read out the solid-state image pickup device 2 at a high speed in a period shorter than one field or one frame period. An incident optical signal is blocked by the light blocking means 1. The signal output from the solid-state image sensor 2 is output by the storage means 4 over a period of one feed or one frame.
[Selection] Figure 1

Description

  The present invention relates to a solid-state imaging device, and more particularly to a solid-state imaging device using a focal plane readout type solid-state imaging device.

  As solid-state image sensors of the focal plane readout method in which the imaging time varies depending on lines and pixels within the imaging region, for example, an amplification type solid-state image sensor, an XY address type solid-state image sensor, and the like are known.

  For example, an amplification type solid-state imaging device includes a pixel transistor for amplifying an optical signal for each pixel, and reads out a signal using electric charge accumulated in the pixel or the like as current modulation of the pixel transistor. FIG. 3 is a diagram illustrating a circuit configuration of an amplification type solid-state imaging device of a capacitive load operation method. In this amplifying solid-state imaging device 5, light receiving elements constituting a plurality of unit pixels, that is, pixel transistors, for example, pixel MOS transistors 6 are arranged in a matrix, and the gate for each row of the pixel transistors 6 is constituted by a shift register or the like. Connected to a vertical selection line 8 selected by a vertical scanning signal (ie, vertical selection pulse) ΦV [ΦV1,... ΦVi, ΦVi + 1,. Are connected to the vertical signal line 9.

A load capacitance element 11 that holds a signal voltage (charge) is connected to the vertical signal line 9 via an operating MOS switch 10. The load capacitive element 11 is connected between the vertical selection line 8 and the ground potential. An operation pulse Φ _DPS is applied to the gate of the operation MOS switch 10.

Vertical signal between the source and the operation MOS switch 10 of the pixel MOS transistor 6 line 9 is connected to a reset bias voltage supply terminal [Phi _RB via the reset MOS switch 12 which also serves as a reset of the reset and the vertical signal line load capacitance element 11 The A reset pulse Φ _RST is supplied to the gate of the reset MOS switch 12.

  The horizontal scanning circuit 13 is composed of a shift register or the like. The horizontal scanning circuit 13 sequentially applies horizontal scanning pulses ΦH [ΦH1,... ΦHn, ΦHn + 1 to the gate of the horizontal MOS switch 15 connected to the horizontal signal line 14. ,...] Are supplied.

In the amplification type solid-state imaging device 5, as shown in the drive timing chart of FIG. 4, first, during the horizontal blanking period HBK, before the read operation period T2 of the pixel MOS transistor 6, that is, the vertical signal in the reset period T1. The line 9 and the load capacitive element 11 are reset to the reset bias voltage V _RB . In other words, the reset pulse Φ _RST and the operation pulse Φ _DSP are applied to turn on the reset MOS switch 12 and the operation MOS switch 10 simultaneously. As a result, the initial voltage of the vertical signal line 9 and the load capacitive element 11 before the read operation period T2 of the pixel MOS transistor 6 is reset to the reset bias voltage V _RB .

Thereafter, the reset MOS switch 12 is turned off, and the vertical selection pulse ΦVi is applied to the vertical selection line, for example, the i-th vertical selection line 8. At this time, the operation pulse Φ _DSP is continuously applied, and the operation MOS switch 12 is in the ON state. At this time, the signal voltage for one horizontal line of the pixel transistors 6 in the i-th row selected is held in each load capacitance element 11. In the pixel reset period T3 at the end of the horizontal blanking period HBK, for example, the substrate pulse _ΦSUB is applied to the substrate, and the signal charge accumulated in the pixel MOS transistor 6 is discharged to the substrate side.

  Next, the signal voltages held in these load capacitance elements 11 are sequentially leveled by the horizontal scanning signals ΦH [ΦH1,... ΦHn, ΦHn + 1,. When the MOS switch 15 is turned on, it flows as a signal charge to the horizontal signal line 14 and is output as a signal voltage through the output circuit.

  After the i-th row of pixel transistors 6 are read to the load capacitance element 11, the pixel MOS transistors of each row such as the next i + 1 rows are read to the load capacitance element 11. The pixel MOS transistor 6 enters an exposure period after being read by the load capacitor element 11 in the horizontal blanking period HBK.

  FIG. 5 is a diagram showing exposure and readout states for each horizontal line in the normal operation of the amplification type solid-state imaging device. In this example, the interlaced readout method is used. In the first field, signals of two pixels adjacent in one vertical direction are mixed and read out, and in the second field, signals of two pixels adjacent in the other vertical direction are mixed. Read out. Pixels corresponding to one field are read out over one field period (for example, 1/60 seconds). The nth line from the first line corresponds to the first field, the 2nth line from the (n + 1) th line corresponds to the second field, and one frame is formed by the first field and the second field. The exposure time Ta1 of each horizontal line corresponds to one field period and is sequentially shifted by one horizontal period consisting of one horizontal blanking period HBK and effective scanning period TA in the readout period.

  FIG. 6 is a diagram showing exposure and readout states of each horizontal line when the electronic shutter operation is performed. The accumulated charge is discharged in the hatched period Tb, and the remaining period is the exposure time Ta2. In other words, the normal electronic shutter is an operation in which the exposure time is shortened without changing the reading speed in the normal operation.

  In such a system, the readout time differs between the upper line and the lower line. In particular, when an electronic shutter operation is performed, as shown in FIG. 6, the difference in readout timing with respect to the exposure period becomes large.

  For this reason, when a moving object or the imaging apparatus itself moves, a time difference occurs between the top and bottom of the captured image, and as a result, the captured image is distorted with respect to an actual subject as shown in FIG. In particular, distortion is noticeable when an electronic shutter operation is performed.

  In order to reduce such distortion, one described in JP-A-9-181986 is known. A block diagram showing the configuration is shown in FIG. In FIG. 8, the solid-state imaging device 16 is the amplification type solid-state imaging device shown in FIG. 3, and the timing generator 17 generates a timing signal that defines the operation timing of the amplification type solid-state imaging device and inputs the timing signal to the solid-state imaging device 16. The memory 18 receives the output of the solid-state imaging device 16 and accumulates it, and then outputs it at a speed different from the input.

  Next, this operation will be described with reference to FIG. FIG. 9 is a diagram showing exposure and readout states when an electronic shutter operation is performed in an amplification type solid-state imaging device of an interlace readout type. As shown in FIG. 9, pixel readout per field is read at high speed in a period shorter than one field period. The output is input to the memory 18. The memory 18 reads this signal over a period corresponding to one field.

According to the above, since the reading speed is high-speed in a period shorter than one field period, the difference in exposure timing between the upper line and the lower line can be reduced as compared with the normal operation. For this reason, it is possible to reduce the distortion of the captured image that occurs when the moving object or the imaging apparatus itself is moved.
JP 9-181986 (paragraphs [0002] to [0013], paragraphs [0021] to [0035])

  However, in the above-described conventional configuration, the difference between the exposure times of the upper and lower lines does not become zero, so the distortion that occurs when a moving subject is imaged is not completely eliminated. In particular, the shorter the exposure time using the electronic shutter function, the more noticeable distortion occurs.

  The present invention solves the above-mentioned conventional problems, and an object thereof is to provide a solid-state imaging device that does not cause any distortion even when a moving subject is imaged.

The invention described in claim 1 of the present invention
A solid-state imaging device that converts an optical signal into an electrical signal and outputs the electrical signal in a period shorter than one field or one frame period; a light-shielding unit that shields an optical signal incident on the solid-state imaging device for a predetermined time; A timing generation means for defining a read timing and a light shielding timing of the light shielding means; and an accumulation means for accumulating the output of the solid-state imaging device and outputting it in one field or one frame period. In the solid-state imaging device, incident light is shielded by the light shielding means during a reading period.

  The invention according to claim 2 of the present invention is the solid-state imaging device according to claim 1, which has an electronic shutter function capable of varying the exposure time.

  As described above, according to the present invention, since the exposure time of the upper line and the lower line of the image are exactly the same, no matter how much the exposure time is shortened using the electronic shutter, the moving subject is imaged. The excellent effect of not producing any is obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

(Embodiment 1)
FIG. 1 is a block diagram showing an example of the configuration of the solid-state imaging device of the present invention.

  In FIG. 1, reference numeral 2 denotes an amplification type solid-state image pickup device as described in the prior art, for example, which is a solid-state image pickup device having a different exposure time for each line. Reference numeral 1 denotes a light shielding means for shielding a light signal incident on the solid-state imaging device 2 for a predetermined time. For example, it can be easily realized by using a mechanical shutter or an electronic device that can control transmitted light such as liquid crystal. . Reference numeral 3 denotes a timing generator that defines the readout timing of the solid-state image sensor 2 and the light-shielding timing of the light-shielding means 1. For example, by outputting the readout start timing of the solid-state image sensor 2 and the light-shielding timing pulse of the light-shielding means 1 Control each timing. Reference numeral 4 denotes storage means for inputting the output of the solid-state imaging device 2 and storing it for a certain period of time, and then outputting it at a speed different from that of the input.

  The operation of the solid-state imaging device configured as described above will be described with reference to FIG. FIG. 2 is a diagram showing exposure and readout states when an electronic shutter operation is performed in an amplification type solid-state imaging device of an interlace readout type. As shown in FIG. 2, pixel readout per field is read out at a high speed in a period shorter than one field period, and the output is input to the storage means 4, and the storage means 4 applies this signal to the period corresponding to one field. Read out. The operation so far is the same as the conventional operation. In the operation of the first embodiment of the present invention, during the period when the solid-state imaging device 2 is being read at high speed, the light signal incident by the light shielding means 2 is shielded, and the discharge operation of the accumulated charges is performed for all lines. This is performed at the same timing for the other pixels. For this reason, the exposure time is the same for all lines, and there is no time difference due to the lines as in the prior art.

  As described above, according to the present embodiment, readout of the solid-state imaging device is performed at a high speed in a period shorter than one field period, and light is shielded during the readout period. Be the same. Therefore, no matter how much the exposure time is shortened by imaging a moving subject, a good image without distortion can be imaged.

  The solid-state imaging device according to the present invention has an excellent effect of imaging a moving subject and causing no distortion no matter how much the exposure time is shortened using an electronic shutter, and is used for imaging a moving image. It is useful as a solid-state imaging device.

The block diagram which shows the structure in Embodiment 1 of this invention. Explanatory drawing which shows the exposure and reading state in operation | movement of Embodiment 1 of this invention. Circuit diagram of amplification type solid-state image sensor Drive timing chart of amplification type solid-state image sensor Explanatory drawing which shows the exposure and reading state in operation | movement of the conventional imaging method Explanatory drawing which shows the exposure and reading state at the time of the conventional electronic shutter operation | movement Explanatory drawing which shows a mode that the image at the time of imaging with the conventional system is distorted 1 is a block diagram illustrating a configuration of an example of an imaging apparatus that reduces conventional distortion Explanatory drawing which shows the exposure and read-out state in the operation of an example of a conventional imaging apparatus that reduces distortion

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light-shielding means 2 Solid-state image sensor 3 Timing generation means 4 Storage means 5 Amplification type solid-state image sensor 6 Pixel MOS transistor 7 Vertical scanning circuit 8 Vertical selection line 9 Vertical signal line 10 Operation | movement MOS switch 11 Load capacitance element 12 Reset MOS switch 13 Horizontal Scanning circuit 14 Horizontal signal line 15 Horizontal MOS switch 16 Solid-state imaging device 17 Timing generating means 18 Memory

Claims (2)

A solid-state imaging device that converts an optical signal into an electrical signal and outputs it in a period shorter than one field or one frame period;
Light shielding means for shielding a light signal incident on the solid-state imaging device for a predetermined time;
Timing generation means for defining the readout timing of the solid-state imaging device and the light shielding timing of the light shielding means;
Storage means for storing the output of the solid-state imaging device and outputting it in one field or one frame period;
A solid-state imaging device, wherein incident light is shielded by the light shielding means during a readout period of the solid-state imaging device. 2. The solid-state imaging device according to claim 1, further comprising an electronic shutter function capable of varying an exposure time.

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