JPS63114473A - Charge coupled image pickup element and its driving method - Google Patents

Abstract

PURPOSE:To sequentially obtain a scanning signal by sharing the reading of the signal charge of photoelectric conversion elements corresponding to an odd number and an even number rows by separate vertical shift registers disposed at both sides and multiplexing for every row in the transfer by a horizontal shift register. CONSTITUTION:A photodiode 12 corresponding to the odd number row 16 of photodiode groups disposed in a matrix on a semiconductor substrate is electrically coupled to the vertical shift register 10 and the photodiode 13 corresponding to an even number row 17 is electrically coupled to a vertical shift register 11 disposed at an opposite side. During a vertical blanking period, a reading pulse is superimposed on vertical transfer pulsesphiV2, phiV4 and the signal charge accumulated on the photodiodes 12, 13 is read to the vertical shift registers 10, 11. The signal charge is simultaneously transferred to the horizontal shift register 15 in parallel for every one row by the vertical transfer pulses phiV1-phiV4. In such a way, the scanning signal can be sequentially obtained in a circuit of simple constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a charge-coupled image sensor that outputs sequential scanning signals;
and its driving method.

[Conventional technology]

In the interlaced scanning system used in current television standards, sideband components caused by sampling cannot be effectively removed from the visual MTF characteristics, resulting in image quality disturbance called interline flicker. Therefore, in recent years, there has been an increasing demand for a progressive scanning method that does not cause interline flicker due to the demand for higher quality images. However, it is impossible to change the readout order of the current charge-coupled image sensor (hereinafter referred to as a CCD image sensor) that supports interlaced scanning to a sequential scanning method due to the device structure. For this reason, conventionally, a sequential scanning signal has been obtained by scanning-converting an interlaced scanning signal obtained from a CCD image sensor using a field memory or the like.

FIG. 6 shows an example of a device for realizing this scan conversion. In FIG. 6, reference numeral 101 denotes an interline transfer type 〇〇D image sensor, and a photodiode group 102. Vertical shift register 103. Horizontal shift register 104 .electrically coupled to one end of vertical shift register 103 . It is composed of an output circuit 105 that detects signal charges from this horizontal shift register 104. Here, the photodiodes 102 are arranged in odd-numbered rows (01), (02
) photodiode groups and even-numbered rows (El),
It is divided into photodiode groups (E2). C.C.
The video signal from the D image sensor 101 is sent to the A/D converter 106.
The signal is converted into a digital signal and input into the field memo January 07 and the time axis converter 108 at the same time. In the time axis converter, line memories 115 to 118
By operating the switches 110 to 114, the signal is converted into a sequential scanning signal compressed at twice the rate in the time axis direction.

Furthermore, the output signal is converted into an analog video signal by a D/A converter 109.

Next, the operation of this scan converter will be explained using the time chart of FIG. From the CCD image sensor 101, the odd numbered row (01) is in the first field.

After the video signals ■ and ■ corresponding to (o2) are output, the second field displays the even-numbered row (El).

Video signals ■′ and ■′ corresponding to (E2) are output (
0 point signal).

The video signals of these even-numbered rows (El) and (E2)
', ■' are stored in the field memory 107, and at the same time, they are directly converted into the line memo January 15. of the time axis conversion unit 108.
116 alternately. At the same time, the field memory 107 outputs the video signals ■, ■ of the odd-numbered rows (01) and (02) delayed by the period of l field, and inputs them alternately to the line memories 117 and 118 ( 0 point signal).

In the time axis conversion unit 108, by switching the switches 112 to 114, the odd numbered row (Of), (02)
The signals ■, ■ and the signals of the even-numbered row (El), the signals ■', ■' of (E2) in the order of the rows, that is, ■.

They are rearranged in the order of ■', ■, ■', and at the same time compressed at twice the rate in the time axis direction. By continuously repeating the above operations, a progressive scanning signal with a frame frequency of 60H2 is obtained (zero point signal).

[Problem that the invention seeks to solve]

As mentioned above, conventional technology uses field memory,
A line memory, an A/D converter, a D/A converter, etc. are required, which increases the circuit scale. Furthermore, the device itself becomes larger.

Furthermore, the CCD image sensor has a photoelectric conversion time of 1/30 second in the frame accumulation mode, and the photoelectric conversion time of the first field and the second field is different from each other by 1/60 second. For this reason, resolution degradation occurs in moving images.

The present invention has improved these problems, and aims to provide sequential scanning with a relatively simple device configuration, no need for a large-scale signal processing circuit, and an accumulation time of 1/60 seconds. An object of the present invention is to provide a CCD image sensor that can obtain a signal.

Another object of the present invention is to provide a method for driving this CCD image sensor.

[Means for solving problems]

The charge-coupled image sensor of the present invention has a group of photoelectric conversion elements arranged in a matrix on a semiconductor substrate, first and second vertical shift registers arranged on both sides of each column of the group of photoelectric conversion elements,
The first vertical shift register is electrically coupled to the photoelectric conversion element group in the odd-numbered row, the second vertical shift register is electrically coupled to the photoelectric conversion element group in the even-numbered row, and
A horizontal shift register electrically coupled to one end of the first and second vertical shift registers is disposed, and an output circuit electrically coupled to one end of the horizontal shift register is further disposed.

The method for driving a charge-coupled image sensor of the present invention includes arranging a group of photoelectric conversion elements in a matrix on a semiconductor substrate, arranging first and second vertical shift registers on both sides of each column of the group of photoelectric conversion elements, The first vertical shift register is electrically coupled to the photoelectric conversion element group in the odd-numbered row, the second vertical shift register is electrically coupled to the photoelectric conversion element group in the even-numbered row, and the first vertical shift register is electrically coupled to the photoelectric conversion element group in the even-numbered row. In a method for driving a charge-coupled image sensor, a horizontal shift register is arranged electrically coupled to one end of a second vertical shift register, and an output circuit electrically coupled to one end of the horizontal shift register. During the video period, video signals corresponding to the photoelectric conversion element groups in the odd-numbered rows are transferred from the first vertical shift register, and video signals corresponding to the photoelectric conversion element groups in the even-numbered rows are transferred to the second vertical shift register. It is characterized in that each row is alternately read out from the shift register to a horizontal shift register, and further horizontally transferred to an output circuit to obtain sequential scanning signals.

[Effect]

In a group of photoelectric conversion elements arranged in a matrix on a semiconductor substrate, signal charges of the photoelectric conversion elements corresponding to odd-numbered rows and even-numbered rows are read out separately from the photoelectric conversion elements arranged on both sides of the photoelectric conversion elements. By assigning the output signals to the vertical shift registers and multiplexing them row by row when transferring the output signals to the horizontal shift registers, a large-scale external signal processing circuit is not required, and a circuit with a relatively simple configuration can be used. A progressive scanning signal can be obtained.

Further, according to the present invention, since video signals simultaneously accumulated for 1/60 seconds can be obtained, resolution deterioration of moving images can be reduced.

〔Example〕

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

FIG. 1 shows the overall configuration of a CCD image sensor according to the invention. In FIG. 1, among the photodiode groups arranged in a matrix on a semiconductor substrate, the photodiodes 12 corresponding to odd-numbered rows 16 are electrically connected to the vertical shift register 10 arranged on one side of each photodiode column. are connected to each other. Further, the photodiodes 13 corresponding to the even-numbered rows 17 are electrically coupled to the vertical shift register 11 arranged on the opposite side. Further, one end of the vertical shift register 10.11 is electrically coupled to the horizontal shift register 14, and the horizontal shift register 14.
One end of is connected to the output circuit 15.

FIG. 2 shows the element configuration of the cell section. In FIG. 2, between adjacent vertical shift registers 10 and 11 and between a vertical shift register and a photodiode, a channel strike area 27 and a photodiode 12 and a photodiode 12 and a photodiode 12 and a vertical shift register and a TG area 25 and a photodiode are connected by a TG area 25 and 26, respectively. 10.11 is electrically coupled to. Also, 2
1 to 24 indicate transfer electrodes.

The operation in the cell section will be explained using the time charts of FIGS. 2 and 3. The vertical shift registers 10.11 are driven by four-phase pulses.

φ9. ~φv4 indicate transfer pulses of the vertical shift register (hereinafter abbreviated as vertical transfer pulses) applied to the transfer electrodes 21 to 24, respectively, and φ94. φV□ corresponds to the odd-numbered row 16 in FIG. 1, and φV3+φv4 corresponds to the even-numbered row F. In the time chart of FIG. 3, time 1. of the vertical blanking period TVIIL. A read pulse is superimposed on the vertical transfer pulse φVZ+φv4, and the signal charge N multiplied in the photodiode 12.13 is read out to the vertical shift register 10.11.

Thereafter, the signal charges read out to the vertical shift register 10.11 are transferred by vertical transfer pulses φv1 to φv4.
The signals are simultaneously transferred row by row toward the horizontal shift register 15 in parallel. Note that the signal charges in the vertical shift register 10 are transferred one transfer stage later than the signal charges in the vertical shift register 11.

FIG. 4 shows the element configuration of the connection portion between the vertical shift register 10.11 and the horizontal shift register 14. In FIG. 4, 41 is the final transfer electrode of the vertical shift register 10.11, 42.43 is the transfer electrode that delays the vertical transfer by 1/2 transfer step in the vertical shift register 11, 44.45 is the transfer gate electrode, 46-- 49 is horizontal shift register 1
Transfer electrodes covering 4 are shown. Vertical shift registers 10.11 arranged on both sides of each photodiode column are electrically coupled directly under transfer gate electrodes 44.45.
Furthermore, it is also coupled to a horizontal shift register 14 .

Next, the operation at this connecting portion will be explained using the time charts of FIGS. 4 and 5. φ, 1゜φDTI are pulses applied to delay transfer electrodes 42.43, φTG are pulses applied to transfer gate electrodes 44.45, and φH++ φ8□ are pulses applied to horizontal transfer electrodes 46 to 49, respectively. shows.

When the signal charges read out to the vertical shift register 10.11 and vertically transferred during the vertical blanking period TVIL reach directly under the final transfer electrode 41, the pulse φTGr φ is turned off at time T2 when the pulse φ9□ turns off. . ,
is turned on, and the signal charges of vertical shift registers 10 and 11 are transferred and accumulated under transfer gate electrodes 44 and 45 and delay transfer electrode 42, respectively. And then φ. OFF, φH, ON, and the signal charges accumulated under the transfer gate electrodes 44 and 45 are
Transferred to horizontal transfer electrodes 46 and 47, and further φ old and φ.

Due to the charge transfer operation, the charge is horizontally transferred to the output circuit during a half of the horizontal effective video period TH.

Next, when φ is turned off and φD2 is turned on, the signal charge under the delay transfer electrode 42 is transferred and accumulated under the transfer electrode 43, and further, at time T3, φTG is turned on.

φ is turned off, and the signal charges under the transfer electrode 43 are transferred and accumulated under the transfer gate electrodes 44 and 45. Then, φA is turned off and φ□ is turned on and transferred to the horizontal transfer electrode 46.47, and due to the charge transfer operation of φ□ and φ6,2, it is transferred to the output circuit in the latter half of the horizontal effective video period T)l. is transferred horizontally.

By repeating the above operations, in vertical transfer,
The signal charges in the vertical shift register 11, which had been transferred one transfer stage ahead, are delayed by 1/2 transfer stage overall, and the signal charges in the vertical shift registers 10 and 11 are transferred row by row to the horizontal shift register 14. The data will be read out alternately and in order.

Through the above operations, sequential scanning signals are obtained.

〔Effect of the invention〕

As described above, according to the CCD image sensor of the present invention,
Reading out signal charges of photoelectric conversion elements corresponding to odd-numbered rows and even-numbered rows is divided into separate vertical shift registers arranged on both sides of the photoelectric conversion element column, and their output signals are By multiplexing each row in horizontal shift register transfer,
Driven by a circuit with a relatively simple configuration, it is possible to directly obtain sequential scanning signals without the need for large-scale external signal processing, and the size of the imaging device itself, including the signal processing system, has been reduced in size. You can floor it.

Further, by using this sequentially scanned video signal, it is possible to obtain a high-quality image with little resolution deterioration and no interline flicker for moving images.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall element configuration in an embodiment of the present invention, FIG. 2 is a diagram showing the element configuration of the cell section of the embodiment in FIG. 1, and FIG. 3 is a diagram showing the operation in the cell section. 4 is a diagram showing the element configuration of the connection part between the vertical shift register and horizontal shift register in the embodiment of FIG. 1, and FIG. 5 is a diagram showing the operation of the connection part of the horizontal shift register. FIG. 6 is a diagram showing the overall configuration of a conventional device, and FIG. 7 is a diagram showing a time chart showing the operation of the conventional example shown in FIG.

Claims (2)

[Claims] (1) A group of photoelectric conversion elements is arranged in a matrix on a semiconductor substrate, and first and second vertical shift registers are arranged on both sides of each column of the group of photoelectric conversion elements, and the first vertical shift register is placed in the odd numbered shift register. electrically coupled to the photoelectric conversion element group in the row of
The second vertical shift register is electrically coupled to the photoelectric conversion element group in the even-numbered row, and an electrically coupled horizontal shift register is disposed at one end of the first and second vertical shift registers, and further A charge-coupled image sensor characterized in that an output circuit electrically coupled to one end of a horizontal shift register is disposed. (2) A group of photoelectric conversion elements is arranged in a matrix on a semiconductor substrate, and first and second vertical shift registers are arranged on both sides of each column of the photoelectric conversion element group, and the first vertical shift register is the odd-numbered shift register. electrically coupled to the photoelectric conversion element group in the row of
The second vertical shift register is electrically coupled to the photoelectric conversion element group in the even-numbered row, and an electrically coupled horizontal shift register is disposed at one end of the first and second vertical shift registers, and further In a method for driving a charge-coupled image sensor in which an output circuit electrically coupled to one end of a horizontal shift register is arranged, a video signal corresponding to a group of photoelectric conversion elements in an odd-numbered row is transmitted to a first The video signals corresponding to the photoelectric conversion element groups in the even-numbered rows are transferred from the second vertical shift register to 1 from the second vertical shift register.
1. A method for driving a charge-coupled image sensor, characterized in that each row is read out alternately to a horizontal shift register, and further horizontally transferred to an output circuit to obtain sequential scanning signals.