JP2974809B2 - Solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device having a function of obtaining vertical and horizontal projection signals required for tracking a moving object.

[0002]

2. Description of the Related Art Various systems for tracking a moving object and detecting a focal point using a video signal have been proposed. For example, Japanese Patent Application Laid-Open No. 2-104637 discloses a system in which video signals are projected in the vertical and horizontal directions, and focus detection is performed based on a differential value of a tracking signal while tracking a moving object. The outline will be described with reference to FIG. For simplicity, a point light source will be described. In the figure, XSUM indicates a signal projected in the vertical direction, YSUM indicates a signal projected in the horizontal direction, and is configured to easily output XSUM and YSUM using a MOS sensor. 9A and 9B show that the time t is t ₀ and t _0
1 shows a mode in which the movement of an image at the time of focusing in ₁ is detected by XSUM and YSUM. Also, FIG. 9 (c)
It shows a slightly blurred state at t = t ₂ , and XSU
The differential values of M and YSUM are smaller than the differential values of XSUM and YSUM at the time of focusing shown in FIGS. 9A and 9B. Then, focus detection is performed according to the magnitude of the differential value.

There is also a system that uses a video signal to focus on changes in its frequency component and detects a focal point. This system is described in "NH Climbing" published by Mr. Ishida et al. In NHK Technical Report Vol. Servo-based Automatic Focusing of Television Cameras ". In this method, focus detection is performed as follows. That is, FIG.
Indicates the defocus and the voltage value of the frequency component,
At the time of focusing, the degree of freshness is high, that is, the high-frequency component is large. On the contrary, at the time of out-of-focus, the edge portion is blurred, that is, the high-frequency component is small. In this way, focusing on the change in the specific frequency, the projection optical system is driven to the peak position of the frequency component to detect the focal point.

[0004]

However, when moving object tracking and in-focus detection are performed by the same sensor, a transfer-type sensor such as a CCD requires a large-scale memory to obtain a projection signal. There is a problem in that a wasteful time is required for reading out each signal and performing digital arithmetic processing, and in a destructive random access type sensor such as a MOS, the signal is lost when read in one direction, and the signal is lost. In addition, there is a problem in that reading in the horizontal direction is wasteful in terms of time, and a signal is lost by reading once, and it is not possible to detect a focal point for each pixel.

Further, as a means for solving the above-mentioned problems, if a signal projected in two directions for tracking a moving object is used as it is in a focus detection method, a high-frequency component having an influence on the focus accuracy will be lost. It is easily lost, that is, averaged (low-pass filter processing) in the projection direction, so that it is difficult to detect a focused point with high accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems in a conventional solid-state imaging device having a moving object tracking and a focus detection function, and performs a moving object tracking and a focus detection with a simple system configuration. It is an object of the present invention to provide a solid-state imaging device capable of performing the following.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention utilizes a solid-state imaging device using a non-destructively readable imaging device such as a charge modulation device. The function of reading the projection signal in the direction is provided. That is, a transistor in which the source / drain current is modulated by the charge generated and accumulated by light irradiation is included as a component of one pixel, the pixels are arranged in a matrix, and the accumulation of the pixel is located around the pixel group. A read signal for reading the source / drain current of the transistor corresponding to the charge, a reset signal for discharging all the stored charge of the pixel, and a part of the stored charge after resetting the pixel and before the next read. A driving means for selectively applying an overflow signal for discharging the signal to a row line commonly connected to the gate of the transistor for each row, and a source line commonly connected to the source of the transistor for each column. Column selecting means for selecting, and amplifying means for converting the source / drain current of the transistor into a voltage. In the solid-state imaging device configured to output signals in time series, the driving unit and the column selecting unit, further, by applying a read signal simultaneously to all the row lines by the driving unit, to read all the pixels, A function of sequentially selecting a source line by a column selecting means and reading out a signal added in a column unit; and applying a readout signal sequentially to each row line by the driving means to make a reading state, and selecting all source lines by a column selecting means. At the same time to read out the added signal on a row-by-row basis.

[0008] In the solid-state image pickup device constructed as described above, the readout signal is simultaneously applied to all the row lines by the driving means to bring all the pixels into a read state, and the source lines are sequentially selected by the column selection means, so that the column unit is selected. Is read out, and this is a vertical projection signal at the time of moving object tracking. Further, by sequentially applying a readout signal for each row line by the driving means to set a read state and simultaneously selecting all the source lines by the column selection means, a signal added in a row unit is read out, and this is used for moving object tracking. Of the horizontal direction.

When the focus is detected, a read signal is sequentially applied to each row by the driving means to set a read state,
The source line is sequentially selected by the column selection means, and the video signal of each pixel is obtained in time series. The reset operation of each pixel is performed by applying a reset signal line by line or simultaneously by the driving means after a predetermined accumulation time has elapsed.

As a result, it is possible to realize a solid-state imaging device capable of obtaining, in a timely manner, vertical and horizontal projection signals required for moving object tracking and video signals required for focus detection.

[0011]

Next, an embodiment will be described. FIG. 1 is a circuit configuration diagram of a first embodiment of the solid-state imaging device according to the present invention. In this embodiment, the present invention is applied to a charge modulating device (Charge Modul).
(hereinafter, abbreviated as CMD). A solid-state imaging device using the CMD imaging device is disclosed in Japanese Patent Application Laid-Open No. 61-84 / 1986.
No. 059 and International El Conference held in 1986.
353 of the proceedings of the ectron Device Meeting (IEDM)
~ 356 "A NEW MOS IMAGE SENSOR OPERATING IN AN
The contents are disclosed in a paper entitled "ON-DESTRUCTIVE READOUTMODE".

In FIG. 1, 1-11, 1-12,... 1-m
n is a CMD constituting each pixel, these are arranged in a matrix, and a video bias V is commonly applied to each drain.
_{Apply DD} (> 0). The gate terminals of the CMDs arranged in the X direction are connected to the row lines 2-1, 2-2,... 2-m, respectively, and the source terminals of the CMDs arranged in the Y direction are the column lines 3-1. , 3-2, ..., 3-n respectively. The column lines 3-1, 3-2,..., 3-n are column selection transistors 4-1, 4-2,. ,..., Signal line 6 and GN via 5-n
D is commonly connected to a reference line 7 grounded. The signal line 6 is connected to a current-voltage conversion type preamplifier 12 whose input is virtually grounded, and an output terminal 9 of the preamplifier 12 is configured to read out a video signal of negative polarity in time series.

The row lines 2-1, 2-2,..., 2-m are connected to the vertical scanning circuit 10, and the signals φ _G1 , φ _G2 ,.
.Phi. _Gm is applied, and column selecting transistors 4-1 4-2,... 4-n and anti-selecting transistors 5-1 5-2,. The gate terminal of the horizontal scanning circuit 11
, And signals φ _S1 , φ _S2 ,... Φ _Sn and respective inversion signals are applied.

Next, the operation of the solid-state imaging device thus configured will be described. First, an operation of obtaining a video signal in the solid-state imaging device having this configuration in order to perform focus detection will be described. FIG. 2 is a signal waveform diagram for explaining an operation of obtaining a video signal in the solid-state imaging device using the CMD imaging device shown in FIG. Row lines 2-1, 2-2,
... The signals φ _G1 , φ _G2 ,... Φ _Gm applied to 2-m are the read gate voltage V _RD for reading the source / drain current corresponding to the accumulated charges generated by light irradiation, and the accumulated charges. Reset voltage V _RST for discharging all the charges and overflow voltage V for discharging a part of the accumulated charges.
_OF and an accumulated voltage V for accumulating charges generated by light irradiation
_In a non-selected row, the storage voltage V _INT is used during the horizontal effective period of the video signal, and the overflow voltage V _OF is used during the horizontal blanking period (note that the overflow voltage V _{OF is used).}
Is described in detail in JP-A-61-136388). In the selected row, the read gate voltage V _RD is used during the horizontal effective period of the video signal, and the reset voltage V _RST is used during the horizontal blanking period.

The column selecting transistors 4-1 and 4-2,
... Signals φ _S1 and φ _S2 applied to the 4-n gate terminal
φ _Sn is a signal for selecting the column lines 3-1, 3-2,..., 3-n.
2,..., 4-n turned off, anti-selection transistors 5-1 and 5-2,
... Turn on 5-n, high level for column selection transistor 4-
1, 4-2, ... 4-n is turned on, anti-selection transistor 5-
1, 5-2,... The voltage value is set so as to turn off 5-n. The optical signal of each pixel CMD is sequentially read out by the signal line 6 and amplified by the preamplifier 12 and output.

Next, an operation for obtaining projection signals in the horizontal and vertical directions for performing moving object tracking will be described. FIG. 3 is a signal waveform diagram for explaining an operation of obtaining a vertical projection signal in the solid-state imaging device using the CMD shown in FIG. The difference from the signal waveform shown in FIG. 2 is that the signal φ applied to the row lines 2-1, 2-2,...
_G1, φ _G2, in · · · phi _Gm, read gate voltage V _RD
Are simultaneously applied to all rows, and the reset voltage V
_RST is not applied. When the read gate voltage V _RD is applied to all the rows, the signals φ _S1 ,
φ _S2, transistor for the column selected by the ··· φ _Sn 4-1,4-
By sequentially turning on 2-n 4-n, it is possible to obtain an added signal of all pixel signals sharing a column line, that is, a signal projected in the vertical direction.

FIG. 4 is a signal waveform diagram for explaining an operation for obtaining a horizontal projection signal in the solid-state imaging device using the CMD shown in FIG. The difference from the signal waveform shown in FIG. 2 is that the column selecting transistors 4-1 4-2,...
Signals φ _S1 , φ _S2 , ... φ _Sn applied to the 4-n gate terminal
Are simultaneously at a high level, during which row lines 2-1 and 2
-2,... The signal φ _G1 , φ _{G2 ,.}
The read gate voltage V _RD is sequentially set, and the reset voltage V _RST is not applied. In a state where all the column lines are selected, the readout gate voltage V _RD is applied to the gate of the pixel CMD line by line, so that an addition signal of all the pixel signals sharing the row line, that is, a signal projected in the horizontal direction is obtained. Obtainable.

In the above-described operation for obtaining the signals projected in the vertical and horizontal directions, since the photocharges accumulated in the pixels are not lost, the operations can be performed during the operation for obtaining the video signal described above. is there.

In this embodiment, in the conventional CMD solid-state imaging device, the function of tracking the moving object is added to the horizontal scanning circuit and the vertical scanning circuit only by adding the function of selecting the output of all the column lines and all the row lines. An effect is obtained that an operation for obtaining a projection signal in the horizontal and vertical directions to be performed can be realized.

FIG. 5 shows a second embodiment of the solid-state imaging device according to the present invention.
FIG. 3 is a circuit configuration diagram of the embodiment. The difference between this embodiment and the first embodiment shown in FIG. 1 is that pixels CMD1-11, 1-12
,... 1-mn each have two source terminals, one of which is the same as the first embodiment, the column lines 3-1,.
3-2,... 3-n, and the other is connected to the second row lines 16-1, 16-2,. The second row line is commonly connected to a projection signal readout signal line 16, and the signal line 16 is connected to a virtual grounded current-voltage conversion type preamplifier 22, and an output terminal 19 of the preamplifier 22 is A negative voltage signal is read.

In this embodiment, the operation of reading the video signal and the operation of reading the projection signal in the vertical direction are exactly the same as those of the first embodiment, so that the description will be omitted. At the point where the horizontal projection signal is read, the row lines 2-1, 2-2,.
The signals φ _G1 , φ _G2 ,... Φ _Gm applied to 2-m are the same as those in the first embodiment shown in FIG. 4, and the row lines 2-1, 2-2,. By applying the read gate voltage V _RD one row at a time to 2-m, an addition signal of signals of all pixels having a common row line, that is, a signal projected in the horizontal direction is applied to the second row line 16-1. , 16-2,... Appear on the projection signal readout signal line 16 via 16-m, and are read out to the output terminal 19 via the preamplifier 22.

In this embodiment, in addition to the effects of the first embodiment, the horizontal scanning circuit only needs to have a function of reading a video signal. The addition signal of all the pixels can be obtained from the output terminal 19 of 22, thereby obtaining an effect that an average signal of all the pixels used for the AE of the camera can be obtained.

FIG. 6 shows a third embodiment of the solid-state imaging device according to the present invention.
FIG. 3 is a circuit configuration diagram showing an example of the present invention. The difference between this embodiment and the first embodiment shown in FIG. 1 is that pixels CMD1-11, CMD1
-12,..., 1-mn each have two source terminals, one of which is the same as the first embodiment.
1, 3-2,... 3-n, and the other is connected to the second row lines 16-1, 16-2,. The second row line is connected via row selection transistors 14-1, 14-2,..., 14-n and anti-selection transistors 15-1, 15-2,. , Are commonly connected to a projection signal readout signal line 16 and a reference line 17 grounded to GND. The projection signal readout signal line 16 is connected to a current-voltage conversion type preamplifier 22 whose input is virtually grounded.
A voltage signal of negative polarity is read out to an output terminal 19 of 22. Also, the row selection transistors 14-1 and 14-
2, ... 14-n and anti-selection transistors 15-1, 15-2, ...
The gate terminals of 15-n are connected to the vertical scanning circuit 13 for reading out the projection signal, and the signals φ _SS1 , φ _SS2,.
SSn and each inverted signal are applied.

In this embodiment, the operation of reading the video signal and the operation of reading the projection signal in the vertical direction are exactly the same as those of the first embodiment, so that the description will be omitted. Next, an operation of reading out a horizontal projection signal in this embodiment will be described. FIG. 7 is a signal waveform diagram for explaining an operation for obtaining a horizontal projection signal in the third embodiment shown in FIG. In this embodiment, the signal waveform for obtaining the projection signal in the vertical direction is the same as that of the first embodiment shown in FIG. 3, and the signal waveforms of FIG. 7 are φ _S1 and φ _S1 in FIG.
_S2, and _{φ S3, φ SS1, φ SS2} , it is replaced by phi _SS3. Therefore, all the lines 2-1 2-2,... 2-m
, A read gate voltage V _RD is applied simultaneously, and signals φ _SS1 , φ
_SS2 ,..., Row selection transistors 14-1, ₁ according to φ SSm
4-2,... By sequentially turning on 14-n, it is possible to obtain an added signal of all pixel signals sharing a row line, that is, a signal projected in the horizontal direction.

In this embodiment, in addition to the effects of the first embodiment, the horizontal projection signal can be read during the operation of reading the vertical projection signal.
The advantage is that projection signals in both directions can be obtained in a short time.

FIG. 8 is a circuit diagram showing a fourth embodiment of the present invention. The difference between this embodiment and the first embodiment shown in FIG. 1 is as follows. That is, CMD1-11,
1-12, ... 1-mn drain terminals are commonly used for each row
, 26-m, and these row lines are connected to row selecting transistors 24-1, 24-2,.
.. And 25-n, and is connected to the projection signal readout signal line 26 via the antiselection transistors 25-1, 25-2,..., 25-n. The projection signal readout signal line 26 is virtually connected to the video bias V
_A signal which is connected to the preamplifier 32 connected to the _DD and is obtained by converting the voltage of the current flowing into the signal line 26 into a voltage is read from the output terminal 29. Also, the row selection transistor 24
-1, 24-2, ... 24-n and anti-selection transistors 25-1, 25
The gate terminals of -2,..., 25-n are connected to the vertical scanning circuit 13 for reading out the projection signal, and the signals φ _SS1 , φ _SS2,.
... Φ _SSm and respective inversion signals are applied.

In this embodiment, the operation of reading the video signal and the operation of reading the projection signal in the vertical direction are exactly the same as those of the first embodiment, so that the description will be omitted. Next, an operation of reading out a horizontal projection signal in this embodiment will be described. In the present embodiment, the signal waveform for explaining the operation of obtaining the horizontal projection signal is the same as that of the third embodiment shown in FIG. That is, all lines 2-1,
2-2,... A read gate voltage V _RD is simultaneously applied to 2-m, and the row scanning transistors 24-1, 24-2,. By sequentially turning on n, the second row lines 26-1, 26-2,.
The pre-amplifier 32 sequentially converts the drain current flowing through -m into a voltage. By this operation, an added signal of all pixel signals sharing a row line, that is, a signal projected in the horizontal direction is obtained. In this embodiment, the third operation is performed by such an operation.
The same effect as that of the embodiment can be obtained.

[0028]

As described above with reference to the embodiments,
According to the present invention, since a projection signal necessary for moving object tracking can be directly obtained from the solid-state imaging device, a memory is not required unlike the related art, so that the system can be reduced in scale and cost and mounting space can be reduced. Further, since it does not require digital signal processing time for producing a projection signal or exposure time of the sensor only for obtaining the projection signal, the response of the focusing operation can be sped up. In addition, by operating the solid-state imaging device in non-destructive readout, the in-focus information and the information for tracking the moving object can be made the same, so that the effect of improving the in-focus detection accuracy and the like can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a solid-state imaging device according to the present invention.

FIG. 2 is a signal waveform diagram for explaining an operation of obtaining a video signal in the first embodiment shown in FIG.

FIG. 3 is a signal waveform diagram for explaining an operation of obtaining a vertical projection signal in the first embodiment shown in FIG.

FIG. 4 is a signal waveform diagram for explaining an operation for obtaining a horizontal projection signal in the first embodiment shown in FIG. 1;

FIG. 5 is a circuit configuration diagram showing a second embodiment of the present invention.

FIG. 6 is a circuit diagram showing a third embodiment of the present invention.

FIG. 7 is a signal waveform diagram for explaining an operation for obtaining a horizontal projection signal in the third embodiment shown in FIG. 6;

FIG. 8 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 9 is an explanatory diagram showing an outline of a conventional system for tracking a moving object and detecting a focal point.

FIG. 10 is a diagram illustrating a relationship between defocus and frequency components for describing a conventional system that performs focus detection using a video signal.

[Explanation of symbols]

 1-11, 1-12, ... 1-mn: Pixel CMD 2-1, 2-2, ... 2-m: Row line 3-1, 3-2, ... 3-n: Column ... 4-n: column selection transistors 5-1, 5-2,... 5-n: anti-selection transistors 6: signal lines 10: vertical scanning circuit 11: Horizontal scanning circuit 12: Preamplifier

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04N 5/30-5/335

Claims (4)

(57) [Claims] 1. A transistor in which a source / drain current is modulated by electric charge generated and accumulated by light irradiation as a component of one pixel, and the pixels are arranged in a matrix.
A read signal for reading the source / drain current of the transistor corresponding to the accumulated charge of the pixel at a peripheral portion of the pixel group, a reset signal for discharging all the accumulated charge of the pixel, and a reset signal for the pixel. Driving means for selectively applying an overflow signal for discharging a part of the accumulated charge to a row line commonly connected to the gate of the transistor for each row before the next readout; and Column selecting means for selecting a source line commonly connected to the source, and amplifying means for converting the source / drain current of the transistor into a voltage. The amplifying means outputs a video signal of each pixel in time series. In the solid-state imaging device as described above, the driving unit and the column selecting unit further include a readout signal for all row lines simultaneously by the driving unit. Pressure and in the state read out all the pixels,
A function of sequentially selecting a source line by the column selecting means and reading out a signal added in a column unit, and applying a readout signal sequentially to each row line by the driving means to make a reading state, and selecting all the sources by the column selecting means. A function of simultaneously selecting lines and reading out a signal added in units of rows. 2. A transistor having two source terminals whose source / drain current is modulated by electric charge generated and accumulated by light irradiation as a component of one pixel,
A read signal for arranging the pixels in a matrix and reading a source / drain current of the transistor corresponding to the accumulated charge of the pixel at a peripheral portion of the pixel group, and a signal for discharging all accumulated charges of the pixel. A reset signal and an overflow signal for discharging a part of the accumulated charge after resetting the pixel and before the next readout are selectively applied to a row line commonly connected to the gate of the transistor for each row. Driving means; column selecting means for selecting, for each column, a first source line commonly connected to a first source terminal of the transistor; and the first source for converting a source / drain current of the transistor into a voltage. A first amplifying means connected via a line, and a second
And a second amplifying means connected to a second source line commonly connected to the source terminals of the first and second source lines. A function of sequentially selecting one source line and outputting a video signal of each pixel in time series from the first amplifying means, and simultaneously applying a readout signal to all row lines by the driving means to read out all pixels A function of sequentially selecting a first source line by the column selecting means and reading out a signal added in a column unit; and applying a readout signal sequentially to each row line by the driving means to set a read state. A solid-state imaging device having a function of reading out a signal added in units of rows from a second source line. 3. A transistor having two source terminals whose source / drain current is modulated by electric charge generated and accumulated by light irradiation as a component of one pixel,
A read signal for arranging the pixels in a matrix and reading a source / drain current of the transistor corresponding to the accumulated charge of the pixel at a peripheral portion of the pixel group, and a signal for discharging all accumulated charges of the pixel. A reset signal and an overflow signal for discharging a part of the accumulated charge after resetting the pixel and before the next readout are selectively applied to a row line commonly connected to the gate of the transistor for each row. Driving means; column selecting means for selecting, for each column, a first source line commonly connected to a first source terminal of the transistor; and the first source for converting a source / drain current of the transistor into a voltage. A first amplifying means connected via a line, and a row for selecting a second source line commonly connected to a second source terminal of the transistor for each row Selecting means, and second amplifying means connected through the second source line for converting the source / drain current of the transistor into a voltage. The driving means sequentially applies a read signal for each row line by the driving means. Readout state, a function of sequentially selecting a first source line by a column selecting means, and outputting a video signal of each pixel in a time-series manner by the first amplifying means, and a function of reading out to all the line lines by the driving means. A signal is simultaneously applied to bring all the pixels into a read state, the first source line is sequentially selected by the column selection means, a signal added in column units is read out, and the second source line is sequentially switched by the row selection means. A solid-state imaging device having a function of reading out a signal selected and added in units of rows. 4. A transistor in which a source / drain current is modulated by electric charge generated and accumulated by light irradiation as a component of one pixel, and the pixels are arranged in a matrix.
A read signal for reading the source / drain current of the transistor corresponding to the accumulated charge of the pixel at a peripheral portion of the pixel group, a reset signal for discharging all the accumulated charge of the pixel, and a reset signal for the pixel. Driving means for selectively applying an overflow signal for discharging a part of the accumulated charge to a row line commonly connected to the gate of the transistor for each row before the next readout; and Column selecting means for selecting a source line commonly connected to the source of the transistor, first amplifying means for voltage-converting the source / drain current of the transistor, and a drain commonly connected to the drain of the transistor for each row A line selecting means for selecting a line; and a drain connecting means for converting a source / drain current of the transistor into a voltage. And a driving unit sequentially applies a readout signal for each row line to set a readout state, and a column selection unit sequentially selects a source line to output each pixel from the first amplification unit. And a function of outputting a video signal in a time-series manner, and simultaneously applying a readout signal to all row lines by the driving means to put all pixels in a read state, sequentially selecting a source line by the column selection means, and by a column unit. A solid-state imaging device having a function of reading out the added signal, sequentially selecting a drain line by the row selecting means, and reading out the added signal in row units.