JP3441741B2 - 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 image pickup device ,
In particular, the present invention relates to a solid-state image pickup device provided with a random access means.

[0002]

2. Description of the Related Art Conventionally, when capturing an image signal in a solid-state image pickup device, there are a bright portion and a dark portion in the same screen, and when exposure is performed in accordance with either one, the bright portion is saturated and the white portion or the dark portion is blown. However, the reproduced image was significantly deteriorated.

As a method for improving this phenomenon, the image signal is stored in the image memory after the first exposure, the bright portion or the dark portion is detected, the exposure amount is adjusted, the second exposure is performed, and the image is re-imaged. By rereading the signal,
There is a method of rewriting the image memory only in a portion where the image is deteriorated by the first exposure.

[0004]

However, the solid-state image pickup device using a plurality of pixels arranged in the horizontal direction and the vertical direction, such as the conventional CCD image sensor or MOS type image sensor, is the second one in the above improvement method. Since all pixels have to be read out after the exposure of, the problem that the photographing time becomes longer by the number of times of re-reading, and the memory for storing the image signal is required, so that the device can be downsized and There was a problem that cost reduction was difficult.

[0005]

Solid-state imaging according to the present inventionapparatus
IsEach pixel has multiple pixels in the vertical and horizontal directions.
Of the photoelectric conversion element and the horizontal and vertical addresses
By receiving each designation, the photoelectric conversion element
Reset means to sweep out accumulated charge and horizontal address
And to receive vertical address designation respectively
Therefore, the charge accumulated in the photoelectric conversion element is used as a signal.
Sample hold means for sample hold and horizontal add
Address and vertical address designation respectively.
And to selectively read the signal from the pixel.
An imaging area including access means, Horizontal address,
Specify the desired pixel by specifying the vertical address
Control the access means of a specified pixel,
Specify the desired address by specifying the address and vertical address.
Specify the element to control the resetting means of the specified pixel.
By specifying the horizontal address and vertical address.
The desired pixel is specified, and the sample of the specified pixel is
A solid-state imaging device provided with a decoder for controlling the hold means.
An image element, Read by the decoder of the solid-state image sensor
Signals from multiple pixels included in the projected imaging area
And a comparison means for comparing a predetermined reference level signal, Previous
Exposure control means for controlling the exposure conditions of the solid-state image sensor;
The level of the read signal is within a predetermined signal level range.
The first pixel determined by the comparison means to be outside the area
To operate the reset means and the sample hold means of
The level of the read signal is within a predetermined signal level range.
The second pixel which is judged by the comparing means to be in the area
Do not operate the reset means and sample hold means of
Control signal to the decoder,
The exposure control means for setting the light condition to another condition
Send a control signal and then set the exposure condition
From the photoelectric conversion element included in the first pixel obtained
The signal is sampled and held, and the level of this signal is
The comparison means determines that the signal level is within the range.
When included, the first pixel and the second pixel are included
In order to output the signals of a plurality of pixels to the signal processing circuit,
Control signal to decoder Control signal generating means for sending Equipped with
It is characterized by that.

The solid-state image pickup device of the present invention has a vertical direction and a water
A plurality of pixels are provided in the horizontal direction, and each pixel has a photoelectric conversion element,
Receives horizontal and vertical address designations
To sweep out the charge accumulated in the photoelectric conversion element
Reset means, horizontal address and vertical address.
The photoelectric conversion element
A sampler that holds the charge accumulated in the child as a signal.
Sample hold means and horizontal address and vertical direction
Depending on the designation of the dress, each pixel
Access means for selectively reading the signal from
Image pickup area, horizontal address, vertical address
By specifying the desired pixel by
It controls the access means and controls horizontal address and vertical address.
Specify the desired pixel by specifying the
The resetting means of the selected pixel, a horizontal address,
Specify the desired pixel by specifying the vertical address
Control the sample and hold means for a specified pixel
A decoder for, and the solid-state image sensor provided with the solid shooting
In the imaging area read by the decoder of the image element
Signals from multiple pixels included and a predetermined reference level signal
And a light exposure section of the solid-state image sensor.
Exposure control means for controlling the condition, and the read signal
If the level is outside the predetermined signal level range, the comparison
A memory for storing the address of the first pixel determined by the step.
Memory, a reset means for the first pixel and a sample host.
Level of the signal read by operating the field means.
Is within the range of the predetermined signal level, the comparing means
Second pixel reset means and sample host
Control the decoder so as not to operate the field means
Based on the comparison result of the comparison means while sending a signal
The exposure control means for setting a predetermined exposure condition
Before sending the control signal to the set exposure condition
The signal from the photoelectric conversion element included in the first pixel is sampled.
Pull and hold the first pixel and the second pixel
Output the signal of multiple pixels including to the signal processing circuit
A control signal generating means for sending a control signal to the decoder, the
It is characterized by having.

[0007]

[0008]

In the solid-state image pickup device of the present invention, the signals from the photoelectric conversion elements of all pixels are sample-held by the sample-hold means provided in each pixel, the sample-held signals are read out, and the exposure amount is too large. It detects whether there is a pixel where the signal is saturated or there is a pixel where the signal level is low due to too little exposure (whether the level of the sampled and held signal is within a predetermined signal level range or not). Based on the detection result, only the pixels that have too much exposure or too little exposure are reset, the exposure is adjusted and the exposure is performed again. The signals from the conversion elements are sampled and held, and when the signal levels of all the sampled and held pixels are within a predetermined signal level range, the signals from all the pixels are sampled and held. It is intended to be read from the de means in a predetermined order.

According to the present invention, even when a new exposure is required, the reset operation and the sample hold operation are performed only for the required pixels, and the signals of the other pixels are the signals obtained by the previous exposure. Since it is possible to keep the above values, the signals of all the pixels read from the sample hold means after the new exposure become the signals in which the already required pixels are rewritten by the signals of the new exposure. An external memory or the like for storing the image signal obtained by exposure is unnecessary.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings.

[First Embodiment] FIGS. 1 and 2 best show the features of the present invention. FIG. 1 shows a schematic configuration of a solid-state image sensor according to the present invention, in which 1 is an imaging region having a plurality of pixels arranged in the H direction and V direction, and 2 is an imaging region.
Is one pixel, 3, 4, and 5 that make up the imaging region 1.
Are H-direction decoders of a random access circuit, a random reset circuit, and a random sample circuit, respectively. 6 is the address line in the H direction, 7, 8 and 9 are respectively
It is a V direction decoder of a random access circuit, a random reset circuit, and a random sample circuit. 10 is a V direction address line, 11 is a data line, 12 is an output circuit,
Reference numeral 13 is an output terminal of the solid-state image sensor, 14 is a control line of the H-direction decoder, and 15 is a control line of the V-direction decoder.

FIG. 2 shows a pixel 2 of the solid-state image pickup device, in which D1 and C1 are photodiodes and storage capacitors which are photoelectric conversion elements, T1 is a reset transistor for resetting the photodiode D1, and T2 and T3 are the first stage. A source follower circuit, T4 is a sample transistor, C2 is a sample capacitor, T5 and T6 are second-stage source follower circuits, T7 is a V direction access pass transistor whose gate is connected to a V direction access address line, and T8 is a gate. An H-direction access pass transistor connected to the H-direction access address line, T9 a V-direction reset pass transistor whose gate is connected to the V-direction reset address line, and T10 a gate connected to the H-direction reset address line. H-direction reset pass transistor, T11 gates in V-direction The V-direction sample pass transistor connected to the pull address line, T12 is the H-direction sample pass transistor whose gate is connected to the H-direction sample address line, and 16 is the output terminal of the pixel connected to the data line 11. .

The signal read operation of the solid-state image pickup device will be described below with reference to FIGS. 1 and 2.

First, the H-direction reset pulse φHr and the V-direction reset pulse φVr shown in FIG. 2 are applied to turn on the H-direction reset pass transistor T10 and the V-direction reset pass transistor T9, thereby turning on the reset transistor T1. , Sweep out the electric charge stored in the storage capacitor C1.

Next, the reset transistor T1 is turned off, the photodiode D1 is exposed as much as necessary, and the charge is stored in the storage capacitor C1. At this time, since the charge amount is converted into the voltage value by the source follower circuit in the first stage, the H direction sample pulse φHs and the V direction sample pulse φVs are added to the H direction sample pass transistor T12 and the V direction sample pass transistor T11. By turning on, the sample transistor T4 is turned on and the voltage value thereof is held in the sample capacitor C2.

Next, the sample transistor T4 is turned off. The voltage value held in the sample capacitor C2 can be held until the sample transistor T4 is turned on again by the sample pulse. The voltage value of the H-direction access pass transistor T8 and the V-direction access pass transistor T8 is obtained by adding the H-direction access pulse φHa and the V-direction access pulse φVa.
By turning on 7, the output is made from the output terminal 16 of the pixel. The output voltage value is the data line 11 shown in FIG.
An image signal is output from the solid-state image sensor through the output circuit 12 and the output terminal 13 of the solid-state image sensor.

FIG. 3 is a block diagram showing a peripheral circuit of the solid-state image pickup device in the solid-state image pickup device using the solid-state image pickup device shown in FIG. 1, in which 17 is a solid-state image pickup device, 18 is a comparator, and 19 is a comparator. A control signal generator, 20 is a shutter and diaphragm as means for adjusting the exposure amount, and 21 is an image signal line.

Now, the signal read operation according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3.

First, the random reset circuit of the solid-state image pickup device 17 is operated to reset the charges of the photodiode D1 and the storage capacitor C1 of all pixels in a predetermined order, and after the first exposure is performed under a certain exposure condition. The random sampling circuit is operated to convert the charges accumulated in the photodiode D1 and the storage capacitor C1 of all pixels into a voltage and sample and hold the charges in a predetermined order.

Next, the random access circuit is operated to read out the image signals sampled and held by all pixels in a predetermined order and output from the solid-state image pickup device 17. The comparator 18 receives a predetermined reference signal from the control signal generator 19, compares it with the image signal, and returns the result to the control signal generator 19. Here, a case where a predetermined reference signal is set low so that a dark portion can be detected will be described. In the control signal generator 19, if the signal currently being compared is lower than a predetermined reference signal, the solid-state image sensor 17
The pixel of the same address is reset and the second exposure is started. In the second exposure, the exposure amount is increased by lengthening the exposure time or adjusting the shutter and diaphragm 20. After the second exposure, after the signal of the pixel corresponding to the detected dark portion is sampled and held, the solid-state imaging device 17
If the result is judged to be good, the signals of all pixels are read out in a predetermined order and output from the solid-state image sensor 17, and the image signal line 2 is read.
It is output to a signal processing circuit or the like through 1. By repeating this operation a necessary number of times, it is possible to increase the sensitivity of the dark part, and thus it is possible to expand the dynamic range. Then, even if this operation is repeated, it is not necessary to read all pixels every time, so that the problem that the photographing time becomes long is solved. It is also possible to set a predetermined reference signal high so that a bright portion can be detected. In this case, 2
At the time of the second exposure, it is possible to prevent the bright portion from being saturated and flying white by reducing the exposure amount by shortening the exposure time or adjusting the shutter and diaphragm 20. Can be expanded. Further, since the same pixel does not become a bright portion and a dark portion at the same time, by sending a reference signal with a lower setting and a reference signal with a higher setting to the comparator 18,
Since it is possible to determine the bright part and the dark part and determine the second exposure condition for each, it is possible to expand the dynamic range of both the bright part and the dark part. Further, according to the present invention, the image memory for storing the image signal is not required, so that the device can be downsized and the cost can be reduced.

[Second Embodiment] FIG. 4 is a block diagram showing a second embodiment of the present invention. The control signal generator 19 shown in FIG.
In addition, 22 address memories are connected. In the present embodiment, as in the first embodiment, after the first exposure, the image signals of all pixels are read out in a predetermined order, the comparator 18 compares them with a predetermined reference signal, and then 2 The address of the pixel determined to require the second exposure is stored in the address memory 22. At this time, the control signal generator 19 stores the address of the pixel determined to require the second exposure in the address memory 22, and
The second exposure condition is calculated from the information sent from the comparator 18. After the comparison of the image signals of all pixels is completed, the pixels stored in the address memory 22 are reset, exposure is performed under the exposure condition calculated by the control signal generator 19, and then,
The pixel signals stored in the address memory 22 are sampled and held. In the first embodiment, the signal of the pixel after the second exposure is compared again by the comparator 18, but in the second embodiment, it is calculated from the signal of the pixel determined to require the second exposure. Since the exposure is performed under the above exposure conditions, it is not necessary to perform the comparison again. Then, the signals of all pixels are read out in a predetermined order, output from the solid-state image sensor 17, and output to the signal processing circuit or the like through the image signal line 21. As a result, it is possible to increase the sensitivity of the dark portion and prevent the bright portion from being saturated and flying white, so that the dynamic range can be expanded. Since the dynamic range can be expanded by only two exposures, the shooting time can be further shortened. Further, in order to expand the dynamic range of both the bright part and the dark part, the reference signal of the lower setting and the reference signal of the higher setting are sent to the comparator 18 from the control signal generator 19, so that the bright part and the dark part are transmitted. And the second exposure condition is calculated for each, and the inside of the address memory 22 is divided into two to store the addresses of the bright portion and the dark portion, or the address memories may be provided separately. . Since the address memory 22 in the second embodiment has a smaller capacity than the image memory for storing the image signal, the device can be downsized and the cost can be reduced.

[Third Embodiment] FIG. 5 is a diagram showing another configuration of the pixel 2 of the solid-state image pickup device 17 used in FIG. 2, in which the H-direction reset pass transistor T10 is omitted and the H-direction reset pulse is used. φHr is connected instead of the power supply, the H-direction sample pass transistor T12 is omitted, and the H-direction sample pulse φHs is connected instead of the power supply. This simplifies the configuration of the pixel 2.

[Fourth Embodiment] FIG. 6 is a diagram showing another configuration of the pixel 2 of the solid-state image pickup device 17 used in FIG. 2, in which the V-direction reset pass transistor T9 is omitted and the V-direction reset pulse is omitted. φVr is connected instead of the power supply, the V direction sample pass transistor T11 is omitted, and the V direction sample pulse φVs is connected instead of the power supply Vdd. This simplifies the configuration of the pixel 2.

In the embodiment of the present invention, the H-direction reset pulse φHr and the V-direction reset pulse φVr are used.
May be replaced with each other, H-direction sample pulse φHs and V-direction sample pulse φVs may be replaced with each other, and H-direction access pulse φH
The a-direction access pulse and the V-direction access pulse φVa may be replaced with each other.

[0026]

As described above, according to the present invention, it is possible to re-expose and re-read only the pixels corresponding to the portion unsuitable as the image signal, so that the sensitivity of the dark portion can be increased or the bright portion can be brightened. Since it is possible to prevent the part from being saturated and flying white, it is possible to expand the dynamic range and shorten the shooting time. Further, since each pixel is provided with the sample hold means, the image memory for storing the image signal is not required, and the device can be downsized and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a solid-state image sensor according to the present invention.

FIG. 2 is a circuit configuration diagram showing pixels of a solid-state image sensor.

FIG. 3 is a block diagram showing a first embodiment of the present invention.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

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

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

[Explanation of symbols]

1 Imaging area 2 pixels 3 R-axis decoder H-direction decoder 4 H direction decoder of random reset circuit 5 H direction decoder of random sampling circuit 6 H direction address line 7 V direction decoder of random access circuit 8 V direction decoder of random reset circuit 9 Random sampling circuit V direction decoder 10 V direction address line 11 data lines 12 Output circuit 13 Output terminal of solid-state image sensor 14 H direction decoder control line 15 V direction decoder control line 16 pixel output terminal 17 Solid-state image sensor 18 Comparator 19 Control signal generator 20 shutter, diaphragm 21 Image signal line 22 address memory

Claims (2)

(57) [Claims] 1. A plurality of pixels are provided in a vertical direction and a horizontal direction, and each pixel includes a photoelectric conversion element, and reset means for sweeping out charges accumulated in the photoelectric conversion element by receiving designation of a horizontal address and a vertical address, respectively. the pixel by receiving the sample and hold means for sampling and holding the charge accumulated in the photoelectric conversion element by receiving the horizontal address and the specification of vertical address respectively as the signal, a horizontal address and a specification of vertical addresses respectively An image pickup area including access means for selectively reading out the signal from the image pickup area, and a desired pixel is designated by designating a horizontal address and a vertical address, and the access means of the designated pixel is controlled to Designate desired pixel by designating address and vertical address Te, a decoder controlling said reset means of the designated pixel, horizontal address, by specifying the desired pixel by specifying the vertical address, and controls the sample-and-hold means of the designated pixel,
Read by the solid-state image sensor provided with, and the decoder of the solid-state image sensor.
Signals from multiple pixels included in the imaging area
Comparing means for comparing with a quasi-level signal, and exposure controlling means for controlling the exposure conditions of the solid-state imaging device
And the level of the read signal is within a predetermined signal level range.
The first pixel determined by the comparison means to be outside the area
To operate the reset means and the sample hold means of
The level of the read signal is within a predetermined signal level range.
The second pixel which is judged by the comparing means to be in the area
Do not operate the reset means and sample hold means of
Control signal to the decoder,
The exposure control means for setting the light condition to another condition
Send a control signal and then set the exposure condition
From the photoelectric conversion element included in the first pixel obtained
The signal is sampled and held, and the level of this signal is
The comparison means determines that the signal level is within the range.
When included, the first pixel and the second pixel are included
In order to output the signals of a plurality of pixels to the signal processing circuit,
A solid-state imaging device , comprising: a control signal generating unit that sends a control signal to a decoder . 2. A plurality of pixels are provided in the vertical and horizontal directions.
Well, each pixel has a photoelectric conversion element, horizontal address and vertical
By receiving each address designation,
Reset means for sweeping out the charge accumulated in the conversion element and water
Accepts both flat address and vertical address
The charge accumulated in the photoelectric conversion element
Sample and hold means for sample and hold
And specify the horizontal and vertical addresses.
The signals are selectively received from the pixels by receiving the signals.
By specifying the horizontal and vertical addresses and the imaging area that includes access means for reading
Of the specified pixel, and the access means of the specified pixel
Control and specify the horizontal and vertical addresses
Specify the desired pixel with the
Controls the setting means to specify the horizontal and vertical addresses.
The desired pixel by specifying the
A decoder for controlling the sample-and-hold means of the element,
Read by the solid-state image sensor provided with, and the decoder of the solid-state image sensor.
Signals from multiple pixels included in the imaging area
Comparing means for comparing with a quasi-level signal, and exposure controlling means for controlling the exposure conditions of the solid-state imaging device
And the level of the read signal is within a predetermined signal level range.
The first pixel determined by the comparison means to be outside the area
Memory for storing the address of the first pixel, reset means for the first pixel, and sample and hold
The stage to operate so that the level of the read signal is at a predetermined level.
The comparison means determines that the signal level is within the signal level range.
Second pixel resetting means and sample hold hand
Send a control signal to the decoder to prevent the stage from operating.
And is determined based on the comparison result of the comparison means.
Control signal to the exposure control means in order to set different exposure conditions.
No. 1 to obtain the first exposure obtained under the set exposure conditions.
The signal from the photoelectric conversion element included in the pixel is sampled
A plurality of units including the first pixel and the second pixel
To output the signal of the pixel of the
A solid-state image pickup device , comprising: a control signal generating means for sending a control signal to a reader.