JPS60250787A - Solid-state image pickup device and method of driving - Google Patents

Abstract

PURPOSE:To double the dynamic range in vertical direction by dividing signal charge in a photodiode into lines of odd number and even number during vertical flyback time of TV signals, and shifting them to upper and lower sections and reading the charge in video period in order from the smaller number of line having signal charge. CONSTITUTION:Signal charge of odd number lines is accumulated in an acumulting section 700' in order of 1, 3, 5...th lines at a position near CCD300' in the horizontal direction, and signal charge of even number lines is accumulated in an accumulating section 700 in order of 2, 4, 6...th lines at a position near CCD300 in the horizontal direction, and read out successively from singnals in low-numbered lines. In this vertical video period, the signal charge in accumulating sections in every upper and lower line is shifted to CCD300, 300' in the horizontal direction, and at the same time, read out in a horizontal video period. In such a way, signal charge in two lines can be read out independently. As every one line is accumulated in separate area and transferred, substantial CCD dynamic range in the vertical direction can be increased twice as much as before.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a solid-state imaging device having a signal charge storage section consisting of a capacitance column for storing signal charges generated by a photodiode, etc., and a charge transfer element connected to the signal charge storage section. It concerns the structure of the device and its driving method.

[Background of the invention]

A frame transfer interline solid-state imaging device (F, 1.T.) using a charge-coupled device (COD) and having a photoelectric conversion section consisting of a photodiode.

An example of this is shown in Figure 1 (Television Society of Japan 1983 Annual Conference Proceedings 3-10).

Reference numeral 400 denotes a light receiving section, which includes a photoelectric conversion element group 600 that converts incident light into signal charges and accumulates them, and a charge coupled device (COD) that transfers the charges accumulated in each photoelectric conversion element section in the direction of the vertical arrow. 101, 102, . . . Consists of an ION and a switching MO8-FET (hereinafter abbreviated as switch MO8T) 206 that transfers signal charges from the photoelectric conversion element to the charge coupled device.

In the following, a driving method will be outlined for the case where two rows of signal charges are simultaneously read out using a general two-row simultaneous readout method in COD (Television Society Technical Report gD691). The signal charge accumulated in the photoelectric conversion element group 600 (hereinafter the signal charge in the diode in the next row is written as St) is applied to the terminal 200, and is transferred to the charge coupled device 101, 102 through the switch MO8T206 which is turned on by the pulse φVQ. ,...Move to ION. Then, the signal charges (S+
, S2+83, 84+, . The above operation is performed during the vertical retrace period of the television signal, and during the video period, the signal charges in the storage section 700 are sequentially converted into charges in the horizontal direction in each horizontal retrace period by pulses φM4 to φM4 applied to the terminals 301 to 304. The signal is transferred to the coupling element 300 and output as a video signal from the output terminal 205 through the output circuit 500 in response to the pulse φH applied to the terminal 207 during the horizontal video period.

By the way, in the device shown in Fig. 1, the vertical COD is composed of a four-phase type COD consisting of four electrodes (two electrodes per row of photoelectric conversion element groups), so there is only one signal charge per four electrodes. Unable to transfer. Therefore, since the signal charges of two adjacent rows cannot be transferred independently, they are transferred together.

This effect appears as resolution deterioration and moiré when a single-chip color imaging device is constructed using the device shown in FIG. Therefore, it is necessary to read out the signal charges of all photoelectric conversion element groups independently for each field.

[Purpose of the invention]

The purpose of the present invention is to improve such conventional drawbacks,
The signal charges of all pixels (photoelectric conversion elements) can be read out independently without increasing the number of vertical COD stages or lines in the light receiving section.
An object of the present invention is to provide a frame transfer interline type solid-state imaging device that can increase the dynamic range of D, and a method for driving the same.

[Summary of the invention]

To achieve the above object, the present invention provides a switch MO8T that transfers signal charges from a photoelectric conversion element to a vertical COD.
206 is provided with a structure in which each row can be operated independently by a shift register, and there are storage sections that can store signal charges of half or more of the number of photoelectric conversion elements on the upper and lower sides of the light-receiving surface 400, respectively, and their signals. A horizontal CCD is provided to read out the charge, and the number is changed so that the signal charge transferred to the lower storage section can be read from the row with the lowest number (the row at the top of the light receiving section) in the same way as the signal charge in the upper storage section. The driving method is characterized in that the young rows are accumulated at 11 A, which is close to the COD in the horizontal direction.

[Embodiments of the invention]

The present invention will be explained in detail below with reference to Examples.

FIG. 2 is a diagram showing the structure of a solid-state imaging device according to the present invention. 100 is a vertical shift register for sequentially and independently opening and closing the gates of switches MO8T in every other row (for example, in odd-numbered rows), and selects the pulse φVT to be applied to the second row 212 and applies it to the gate of the switch 0IaST in each row. On the other hand, a pulse φVQ is applied to the terminal 200 of the gates of the switches MO8T in the remaining rows (for example, several rows of ducks) so that they can be opened and closed simultaneously.

700 and 700' are both storage sections having a structure similar to the CCD in the vertical direction of the light receiving section, 300.degree. 300' is the COD in the horizontal direction, and 500 and 500' are output circuits.

In FIG. 2, the signal charge in the photodiode is transferred to the upper and lower storage sections during the vertical blanking period of the television signal. That is, φ
The photodiode signal charges of even-numbered rows connected to the switch 'MO8T controlled by the v6 pulse are stored in the upper storage section 700.
The photodiode signal charges in the odd rows connected to the switch MO8 controlled by the φVT pulse are transferred to the lower storage section 700'. Thereafter, during the video period of the television signal, the signal charges in the upper and lower storage sections are read out in order from the row with the lowest number and taken out as a video signal.

FIG. 3 shows an example of a driving method for carrying out the above operation. First, when entering the vertical retrace period, terminals 201 and 202
φv3 pulse 401. to one terminal 203.204 to keep it in the OFF state. A φv4 pulse 402 is applied to turn it on, so that charges can be stored only under the COD electrode in the vertical direction connected to the terminals 203 and 204. and terminal 20
0, a φVQ pulse 403 is applied to transfer the signal charges of the photodiodes in the even rows to the COD in the vertical direction.

After that, 40 pulses of φVl to φv4 are applied to terminals 201 to 204.
4 is added to terminals 301 to 304 at the same time as φvI to φv.
The same φold to φM4 pulse 405 as in 4 is added and transferred to the upper storage section 700. However, the storage section is for signal charges in even-numbered rows (therefore, the number is half or more than the number of photodiodes)
Make sure that you can accumulate all of them. and terminal 301,
302 is kept in the ON state and signal charges of even-numbered rows are accumulated under the electrodes connected thereto.

Next, the shift register 100 is used to transfer the signal charges of the odd-numbered photodiodes. In other words, first the terminal 20
At the same time, the shift register clock φvs pulse 417 is applied to the terminal 211, and the switch MO8T221, which determines the row from which the signal charge is read out, is turned OFF.
Set to N state. And the terminals 201 and 202 are φVI+
When the φv2 pulses 411 and 412 are in the ON state, the φVT pulse 413 is applied to the terminal 212, and only the signal charge S1 in the first row photodiode is turned on by the vertical CCD.
Take it out. The state at this time is schematically shown in FIG. 4(b).

Figure 4 shows only one vertical CCD1OH, and each stage is a terminal 201 to 201 in the vertical CCD.
The area under each electrode connected to 204 is shown. Also in the figure (×
The region indicated by ) indicates a state in which the electrode in the region above is in an ON state and is in a state where charge can be accumulated, but there is no charge therein yet. After applying pulse 413 φv1~φ
A v4 pulse 414 is applied to transfer the signal charge S1 downward by eight stages. At this time, a φ■ pulse 427 is applied to the terminal 211 to advance the shift register 100 by one stage, and then a φVT pulse 42 is applied to the terminal 211.
3 is added, and the signal charge S3 of the photodiode in the third row is taken out to the region above the charge S1 (FIG. 40). Then, the pulse 424 again transfers the data downward by 8 steps. Similarly, the signal 'charge' of the photodiode in the odd row is S+ + 83
+ Ss +... Take out. At the same time, φM1' to φM4' pulses 415, which are the same as those for φvl to φv4, are applied to the terminals 301' to 304' and transferred to the lower storage section 700'. and terminals 303', 304
' is kept in the ON state and the signal charges of the odd numbered rows are placed under the electrodes connected to this from the side closer to C0D300' in the horizontal direction.
+83 +85... are accumulated in this order.

In other words, by the above operation, the signal charges in the odd rows are transferred to the 1st, 3rd, 5th rows, etc. in the storage section 700'.
The signal charges of even lines are placed in the second row and the fourth row in the storage section 700 in the horizontal direction near the CCD 300' in the order of .
CCD 30 in the horizontal direction in the order of row, 6th row, etc.
Since the signal charges are accumulated at a position close to 0, the signal charges can be read out sequentially starting from the row with the smallest number. Thereafter, during each horizontal retrace period during the vertical video period, the signal charges in the storage section are transferred to the CCDs 300 and 300' in the horizontal direction, one row each on the top and bottom, and read out during the horizontal video period, so that the signal charges in the two rows are independent of each other. can be read out.

Furthermore, according to the present invention, unlike the driving method of the conventional device shown in FIG.
The CD dynamic range is increased by approximately twice that of the conventional method.

Although only the case where the vertical direction COD is of the four-phase type has been described above, the vertical direction COD may be a three-phase type or any other charge-coupled device capable of upward transfer. Also, the signal transfer order is even-numbered lines.

Any of the odd rows may be read first.

By the way, in the area indicated by the (X) mark in FIG. 4, smear charges are accumulated, which are generated when a part of the charges generated in the photodiode portion leaks directly into the CCD in the vertical direction without passing through the switch MO8T206.

This charge mixes with the signal charge and is read out, appearing as a white band in the vertical direction of the screen and deteriorating the image quality (this also occurs in conventional devices).

In the above embodiment, the signal charges of the odd rows are started to be extracted (
Figure 3: Just before adding pulse 413), vertical CO
The case where the two electrodes D are kept in the ON state and the smear charge is held is shown. However, before applying pulse 413, the four electrodes of the vertical COD are turned off at the same time so that they cannot hold charge, or the vertical COD is driven downward once at high speed to remove the smear charge. smear can be further reduced by keeping it in place.

〔Effect of the invention〕

As explained above, according to the present invention, the signal charges of all pixels (photoelectric conversion elements) can be read out field by field without increasing the number of COD stages or CODs in the vertical direction in the light receiving section. The dynamic range of COD can be increased approximately twice as much as that of conventional frame transfer interline solid-state imaging devices.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional frame transfer interline type solid-state imaging device, FIG. 2 is a configuration diagram of a frame transfer interline type solid-state imaging device according to the present invention, and FIG. 3 is a diagram showing its driving direction. FIG. 4 is a diagram for explaining the state of charge transfer in this driving method. 100... Vertical shift register, 101, 102. . ION... CCD in vertical direction, 206... MO8-FET for switch, 300, 300'... Horizontal direction Fig. 1 Fig. 2 Fig. 2θ3' Fig. 3 i4 (α) (b) (Re and d)

Claims (1)

[Claims] 1. A plurality of photoelectric conversion element groups arranged two-dimensionally;
A plurality of charge transfer elements for vertically transferring signal charges accumulated in the photoelectric conversion element group, and a switch for transferring a signal '1' from the photoelectric conversion element group to the vertical charge coupled element. A solid state consisting of a gate group, an accumulation section for temporarily accumulating the signal charges taken out from the photoelectric conversion element group, and a charge transfer element that reads out the signal charges of the accumulation section one row at a time in each horizontal period. In an imaging device, a horizontal wiring that can independently switch gates for every other row by m%, a vertical shift register for applying a pulse voltage to the wiring in a predetermined order, and a group of photoelectric conversion elements. A solid-state imaging device characterized in that a charge transfer element for horizontally transferring a charge to an accumulation part is provided above and below a light receiving part made up of the vertical charge transfer element. 2. In the solid-state imaging device according to claim 1, the storage capacity of the storage sections provided above and below the light receiving section is
A solid-state imaging device in which the number of each photoelectric conversion element is half or more of the number of the photoelectric conversion elements. 3. A plurality of photoelectric conversion element groups arranged two-dimensionally,
a plurality of charge transfer elements that vertically transfer signal charges accumulated in the nuclear photoelectric conversion element group; a switch gate group that transfers the signal charges from the photoelectric conversion element group to the vertical charge-coupled element; A solid-state imaging device comprising an accumulation section for temporarily accumulating signal charges taken out from the group of photoelectric conversion elements, and a charge transfer element for reading out signal charges in the accumulation section one row at a time in each horizontal period, A horizontal wiring capable of independently driving switch gates in every other row, a vertical shift register for applying pulse voltages to the wiring in a predetermined order, and a photoelectric conversion element group and a vertical wiring. In a method for driving a solid-state imaging device, the charge transfer element is provided above and below a light-receiving part made of a charge transfer element for horizontally transferring the charge to the storage part, respectively,
The signal charges sequentially taken out by the vertical shift register are accumulated in an accumulation section provided below the light receiving section, and the remaining signal charges are accumulated in an accumulation section provided above the light receiving section, and the remaining signal charges are accumulated in an accumulation section provided above the light receiving section. 1. A method for driving a solid-state imaging device, comprising accumulating signal charges extracted from the photoelectric conversion element array located in the horizontal direction at a position close to the four charge transfer gates.