JPH04170173A - Image pickup device - Google Patents

Abstract

PURPOSE:To enable the image pickup device to cope with television systems of different scanning ranges through the use of one solid-state image pickup element by employing a switch means selecting any of plural television systems so as to skip reading of undesired picture elements of the image pickup element when a television system whose scanning range is narrower is selected. CONSTITUTION:This device is provided with an image pickup element 121 covering picture element numbers in horizontal and vertical directions for a television system requiring a maximum scanning range among plural televisions handled by the element and a switch means 112 selecting the plural television systems. The switch means 112 is used to read undesired picture elements of the image pickup element 121 at a high speed or to skip reading them when a television system whose scanning range is narrower is selected. Thus, the image pickup device is realized, in which one image pickup element is enough to cover the television systems whose scanning range differs from each other by employing the image pickup element provided with picture element numbers in horizontal and vertical directions to cover a television system requiring a maximum scanning range among plural televisions handled by the element and devising to read undesired picture elements of the image pickup element 121 at a high speed or to skip reading them when a television system whose scanning range is narrower is selected in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an imaging device that captures images compliant with both PAL and NTSC systems using, for example, a solid-state image sensor having a pixel count compliant with the PAL system. It is related to.

[Prior Art] Currently standard television signal processing systems include two different systems: the NTSC system and the PAL system. The biggest difference between these signal processing systems is the number of scanning lines, with the NTSC system having 525 lines and P
The AL system has 625 lines. Because of this difference in the number of scanning lines, conventional solid-state imaging devices compatible with each method using solid-state imaging devices have been created using dedicated solid-state imaging devices with different numbers of vertical pixels.

[Problems to be Solved by the Invention] However, in the conventional imaging device described above, due to a slight difference in the number of scanning lines, the NTSC system and the PA system cannot be used.
The solid-state image sensor used in the L method has to be developed and manufactured separately, which poses a problem of increasing development and manufacturing costs.

Therefore, the imaging device of the present invention has been made in view of the above-mentioned problems, and its purpose is to provide an imaging device that uses a single solid-state imaging device and is compatible with television systems with different scanning ranges. It is about providing.

[Means for Solving the Problems] and [Operations] In order to solve the above problems and achieve the objectives, the imaging device of the present invention has the following features:
An image sensor used for a plurality of television systems having different scanning ranges and having a number of pixels in a horizontal direction and a vertical direction corresponding to a television system having a maximum scanning range among the plurality of television systems, and switching between the plurality of television systems. switch means, and when a television system with a narrow scanning range is selected by the switch means, unnecessary pixels of the image sensor are skipped, thereby making it possible to correspond to television systems with different scanning ranges. It is.

It is also used for multiple television systems with different scanning ranges,
an image sensor having a number of pixels in the horizontal and vertical directions corresponding to a television system with the largest scanning range among the plurality of television systems, and a switch means for switching between the plurality of television systems, and the switch means: When a television system with a narrow scanning range is selected, unnecessary pixels of the image sensor are read out at high speed, thereby making it possible to support television systems with different scanning ranges.

[Example] Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

FIG. 10 is a diagram showing the structure on one chip of an FGA sensor, which is a type of solid-state imaging device and is capable of randomly selecting vertical scanning lines. A detailed explanation of the FGA sensor can be found in the literature (IEEE TRA
NSACTION OF ELECTRON D
EVICE VOL.

35, NO, 5, MAY 1988 p, 646~
652), so we will only give a brief explanation here.

In FIG. 10, 101 is a light receiving element. Light receiving element 1
01 is constituted by a coupling capacitance CO between the gate of a JFET (junction field effect transistor) and the horizontal address line 103. 102 is J constituting the light receiving element 101
The load capacitance of the FET source and the JF of the light receiving element 101
Together with ET, it forms a source follower. A horizontal address line 103 is commonly capacitively coupled to the gates of the JFETs of the light receiving elements 101 forming one horizontal line by a capacitor CO.

A vertical scanning decoder 104 applies a reset pulse φVH to the horizontal address line of the horizontal line selected by the line address data, and applies an off pulse φVL to the horizontal address line of the unselected horizontal line. When the reset pulse ψVH is low, the JFET of the light receiving element 101 is turned on and the gate potential appears at the source. When the reset pulse φVH is high, the coupling capacitance CO of the light receiving section is charged to a predetermined lower charge amount, and the potential of the light receiving element 101 is reset to a predetermined potential. When off-pulse φVL is high, light receiving element 1
JFET 01 is turned on and the gate potential appears at the source. When the off-pulse φVL is low, the J of the light receiving element 101
The FET is turned off and no gate potential appears at the output.

A vertical signal line 105 is commonly connected to the sources of the light receiving elements 101 on the same vertical line, and the gate potential of the light receiving elements on the horizontal line selected by the vertical scanning decoder appears. 1O6 is a clamp circuit composed of the same number of clamp circuits as the vertical signal lines 105, and fixes the potential of each of the vertical signal lines 105 to the reference potential VR when the clamp pulse φC is high.

107 is a sample and hold circuit and line memory;
It is composed of hold capacitors and switches corresponding to the number of vertical signal lines 105. The potential level of each vertical signal line when φsh is high is sampled, and the potential at the moment it becomes low is held. A hold capacitor separated from the vertical signal line becomes a horizontal line memory.

108 is an output amplifier that outputs the potential of the horizontal signal line 109. A switch 110 connects the signal of the sample and hold circuit/line memory 107 to the horizontal signal line 109, and is scanned by the horizontal shift register 111. 11
2 is a switch row composed of switches 110.

FIG. 11 is a diagram showing a timing chart of the operation of the FGA sensor. Line address data is set immediately after the start of the horizontal blanking period. Next, off pulse φ
By making VL low, the JFETs of the light receiving elements 101 of horizontal lines other than the selected horizontal line are turned off, and only the signal of the selected horizontal line appears on the vertical signal line 105. The signal appearing at this time is clamped to the reference potential VR by a clamp pulse φC, and then its level is sampled and held by a sample hold pulse φsh. Next, the clamp pulse φC becomes low, and then the reset pulse φVH becomes high, all charges in the light receiving elements 101 of the selected horizontal line are reset, and the output of the vertical signal line 105 changes.

After the reset pulse φVH becomes low, the potential appearing on the vertical signal line 105 is sampled and held by the sample and hold pulse φsh, so that the light receiving element 10
The change in potential before and after the reset of 1 is stored in the sample and hold circuit/line memory 107. Next, the off-pulse φVL becomes an intermediate potential. Next, the address of the horizontal line to be reset to control the accumulation period is set as line address data, and the reset pulse φVH
By becoming high, the charge of the light receiving element 101 of the designated horizontal line is reset.

When this operation is completed, the clamp pulse φC becomes high again and the potential of the vertical signal line 105 is clamped. Next, scanning by the horizontal shift register 111 of the sample and hold circuit/line memory 107 starts, and the horizontal blanking period ends. Vertical scanning can be performed randomly by providing line address data.

The accumulation period can be set by giving the address of the horizontal line to be reset several H before reading, resulting in an electronic shutter operation of the focal brain.

FIG. 12 is a diagram showing changes in the output of the light receiving element 101, and the output is reset by a reset pulse φVH at time t1. Thereafter, if light is being irradiated, the output potential increases as time passes. The sample and hold circuit/line memory 1 is set to the potential just before being reset again at t2.
The potential of 07 is clamped. A read signal value is obtained by sampling and holding the potential immediately after being reset at t3.

FIG. 1 is a diagram explaining the scanning range in each NTSC%PAL mode of the solid-state image sensor (FGA sensor) 121 in this embodiment, and the number of pixels in the horizontal and vertical directions is equal to the number of pixels required in the PAL system. ing. Address numbers in the vertical direction of the horizontal line are indicated by symbols Y1 to Y5.

The area from Y1 to Y2-1 is a vertical optical black pixel and is a region that serves as a black level reference signal. The area from Y2 to Y5 corresponds to the number of scanning lines during the effective period in the PAL system, and is usually about 580 lines. Y3 to Y
The area up to 4 corresponds to the number of scanning lines during the valid period in the NTSC system, which is usually about 480 lines.

The horizontal address numbers of the vertical lines are indicated by symbols X1 to X5. The pixels X1 to X2-1 are optical black pixels in the horizontal direction, and by clamping the level of these pixels every horizontal scanning period, they become a reference signal of a black reference level. The area from X2 to X5 is the area that is output during the valid period in the PAL system,
The ratio is such that when Y2 to Y5 are set to 3, the ratio becomes 4. X3 to X4 are 8 areas in the valid period in the NTSC system, and are set at a ratio such that when Y3 to Y4 are 3, it becomes 4.

FIG. 2 is a timing diagram illustrating the reading method when the solid-state image sensor 121 is used in the PA, L system and in the NTSC system. During PAL, line address data from Yl to Y is sent during the vertical blanking period.
By giving the address data of 2-1, the optical black part of Y2-1 is read from Yl,
During the vertical valid period, the area from Y2 to Y5 is read by giving address data from Y2 to Y5 as line address data. In NTSC, the optical black area is read out during the vertical blanking period in the same way as in PAL, and the area from Y3 to Y4 is read out by giving the address data from Y3 to Y4 as line address data during the vertical blanking period. conduct.

Regarding the vertical direction, in the FGA sensor having the structure shown in FIG.
A solid-state image sensor having the number of pixels for the PAL system can be used for the NTSC system by skipping portions unnecessary for the NTSC system during vertical scanning.

Next, horizontal reading will be explained. Figures 3 and 4
The figure shows an example of the structure and driving method of the horizontal shift register of the solid-state image sensor 121 for skipping unnecessary parts during NTSC.

A shift register is generally configured with a plurality of flip-flops connected in series to which a clock φS is applied in parallel, and operates so that a start pulse φin is transferred one after another by φS. The shift register shown in FIG. 3 differs from a normal shift register in that there are switches 113, 114, 115, .
116.

Switch 113 enters the shift register between the stage corresponding to address number X2-1 in FIG. 1 and the stage corresponding to address number X2, and turns on/off transmission of pulses between the stages. Switch 114 turns on and off the transmission of pulses from the stage corresponding to X3-1. Switch 115 is a switch that turns on and off the transmission of pulses from the stage corresponding to X2-1, switch 1
16 is a switch that turns on and off transmission of pulses to the stage corresponding to X4 and the stage corresponding to X4+1, and grounds the input of the stage X4+1 when off.

Figure 3 shows the switch settings for PAL, switch 11
3 is connected to the previous stage, switches 114 and 116 are also connected to the previous stage, and switch 115 is turned off. By setting the switches in this manner, all horizontal pixels are scanned, so that a signal compatible with the PAL system can be obtained.

Figure 4 shows the switch settings for NTSC, with switches 113 and 116 being grounded, switch 114 being off,
Switch 115 is in the on state. In this state, after scanning from Xl to x2-1, x2
to X3-1 are skipped, and the horizontal scanning is completed by scanning from X3 to X4. In this way, only the area compatible with the NTSC system can be scanned.

FIG. 5 is a block diagram in which an NTSC1PAL dual-purpose camera is constructed by applying the above-described solid-state image sensor and driving method to an electronic still camera.

201 is a lens, 202 is an aperture, and 203 is a shutter. A shutter aperture drive circuit 204 drives the shutter 203 and the aperture 202 in accordance with a control signal from the system control circuit 214. Reference numeral 121 denotes a solid-state image sensor, which is assumed to be the above-mentioned FGA sensor here. 2
05 is a solid-state image sensor driving circuit, which generates line address data corresponding to the preset NTSC system and PAL system, performs readout drive in the vertical direction, and also performs driving such as high-speed readout of pixels, which will be described later. The solid-state image sensor 121 is controlled.

206 is a clock generation circuit. A signal processing circuit 207 processes the output obtained from the solid-state image sensor to obtain a luminance signal and a color difference line sequential signal. Each pixel of a solid-state image sensor is provided with a color filter array, and there are various methods for obtaining a luminance signal and a color difference signal from one solid-state image sensor, but these will not be discussed here.

208 is an FM that modulates the luminance signal and color difference line sequential signal.
It is a modulation circuit. 209 is an RFC amplifier that amplifies the FM modulated signal so that it can be magnetically recorded. 210 is a magnetic head, and 211 is a magnetic sheet which is a recording medium. 212 is a motor that rotates the magnetic sheet, 213 is a motor servo circuit, and 214 is a system control circuit that controls the operation of the entire system. 215 is a shutter release switch, and in synchronization with the operation of turning on this switch, a series of still image capturing sequences controlled by the system control circuit 214 are performed.

The switch 217 is a changeover switch between NTSC mode and PAL mode, and when it is on, it is NTSC, and when it is off, it is PAL mode. The original oscillation frequency and output clock timing of the clock generation circuit, the rotation speed of the motor 212, and the synchronization signal given to the imaging signal processing circuit 207 are switched by the on/off selection signal of this switch. Further, the selection signal of the switch 217 is transmitted to the solid-state image sensor driving circuit 20.
5, and the solid-state image sensor drive circuit 205 is supplied with the NT
It drives the solid-state image sensor 121 that is compatible with the S'C system and the PAL system, respectively, and operates as an NTSC1PAL dual-purpose camera.

FIG. 6 is a diagram showing a driving sea fence of an electronic still camera. When the shutter release switch 215 is turned on at time T1, unnecessary charges in the A field are cleared, and at T2, unnecessary charges in the B field are cleared. Next, at time T3, the shutter 203 is opened and the exposure operation is started. Reading of the light receiving element information of the A field is started from time T4, and at the same time, the signal is processed and recorded on the magnetic sheet 209 as a still image. Next, at time T5, reading of the light receiving element information of the A field is started, and at the same time, the signal is processed and recorded on the magnetic sheet 209 as a still image.

(Other Embodiments) FIG. 7 is a diagram showing a method of driving a horizontal shift register for skipping unnecessary horizontal portions without having a switch as shown in FIG. 3 during NTSC. During the horizontal blanking period, first, prior to scanning the effective part, the signal of the optical black part is read out at a normal driving frequency, and then the section corresponding to the part from X2 to x3-1 is scanned with high-speed pulses. Next, the scan from X3 to X4 is performed using normal pulses, and then the operation from X4+1 to X5 is performed using high-speed pulses. The solid-state image sensor 121 is controlled by the solid-state image sensor drive circuit 205 so that unnecessary portions are read out in a short time using such a method. By driving in this manner, unnecessary portions can be skipped without using a switch as shown in FIG.

FIG. 8 shows a driving method for quickly clearing the light-receiving portion of the portion that is not read out at N780 in vertical scanning.

As shown in FIG. 8, by sequentially applying reset addresses as line address data and setting the reset pulse φVH high, it is possible to quickly clear the light receiving elements of unnecessary horizontal lines. FIG. 9 shows a driving method for suppressing blooming at N780 using such a fast reset driving method. What is different from FIG. 2 in FIG. 9 is that during the vertical blanking period, Y2 to Y3-
1% Y4+1 to Y5 in the NTSC system performs a set scan of the light receiving element in an area that is not read out. By performing such an operation, it is possible to prevent excessive charges from accumulating in the unread portions and causing blooming.

As explained above, when you want to extract a signal compliant with the NTSC system, you can increase the number of pixels compatible with the PAL system by skipping unnecessary parts in the vertical and horizontal directions, or by reading out at high speed. The equipped solid-state image sensor can also be used for the NTSC system, and the NTSC
, an imaging device compatible with both PAL and PAL systems can be realized.

Note that the present invention can be applied to modifications or variations of the above embodiments without departing from the spirit thereof.

For example, in this embodiment, the NTSC system and the PAL system have been described, but it is also widely applicable to other television systems with different scanning ranges.

Further, although this embodiment has been explained using an example of an electronic still camera, by continuously performing the above-described operations, it is possible to easily configure a moving image camera that is compatible with television systems having different scanning ranges.

Furthermore, by replacing the switches 113, 114, 115, and 116 with AND gates or the like, it is possible to automatically switch the operation of the horizontal shift register between the NTSC system and the PAL system.

[Effects of the Invention] As described above, in the imaging device of the present invention, an image sensor having a number of pixels in the horizontal and vertical directions compatible with a television system with a wide scanning range is used to In the case of this method, by skipping unnecessary pixels or reading them out at high speed, it is possible to realize an imaging device that is compatible with television systems with different scanning ranges using a single image sensor.

[Brief explanation of drawings]

FIG. 1 shows an NT of a solid-state image sensor in one embodiment of the present invention.
A diagram explaining the scanning range in SC and PAL modes. Figure 2 shows the scanning range when using a solid-state image sensor in PAL and NTS.
Figure 3 shows the switch settings for PAL, Figure 4 shows the switch settings for N780, Figure 5 shows the NTSC setting for electronic still cameras. . A block diagram configuring a PAL dual-purpose camera, Figure 6 is a diagram showing the driving sea fence of an electronic still camera, and Figure 7 is a diagram showing an unnecessary part in the horizontal direction at N780 without having a switch like Figure 3. Figure 8 is a diagram showing the driving method of the horizontal shift register for skipping, Figure 8 is a diagram showing the driving method to quickly clear the light receiving part of the part that is not read at N780 in vertical scanning, Figure 9 is driving for high-speed reset. Figure 10 is a diagram showing the structure of the FGA sensor, Figure 11 is a timing chart of the operation of the FGA sensor, and Figure 12 is the light receiving element. FIG. 3 is a diagram showing changes in output. In the figure, 101...Light receiving element, 103...Horizontal address line, 105...Vertical signal line, 110...Switch, 112...Switch row, 113-116...Switch, 121... - Solid-state image sensor, 201... Lens, 202... Aperture, 203... Shutter, 210
...Magnetic head, 211...Magnetic sheet, 212.
... Motor, 215 ... Shutter release switch, 217 ... Switch. Opening: 4-1 (UL15 (15)

Claims (7)

[Claims] (1) Used in multiple television systems with different scanning ranges,
an image sensor having a number of pixels in the horizontal and vertical directions corresponding to a television system with the largest scanning range among the plurality of television systems, and a switch means for switching between the plurality of television systems, and the switch means: An imaging device capable of supporting television systems with different scanning ranges by skipping unnecessary pixels of the image sensor when a television system with a narrow scanning range is selected. (2) The imaging device according to claim 1, wherein unnecessary pixels in the vertical direction are skipped by controlling how addresses are given to horizontal lines. (3) The imaging device according to claim 1 or 2, wherein unnecessary pixels in the horizontal direction are skipped by controlling a shift operation of a horizontal shift register. (4) Used in multiple television systems with different scanning ranges,
an image sensor having a number of pixels in the horizontal and vertical directions corresponding to a television system with the largest scanning range among the plurality of television systems, and a switch means for switching between the plurality of television systems, and the switch means: An imaging device capable of supporting television systems with different scanning ranges by reading out unnecessary pixels of the image sensor at high speed when a television system with a narrow scanning range is selected. (5) The imaging device according to claim 4, wherein unnecessary pixels in the horizontal direction are read out at high speed by controlling a shift operation of a horizontal shift register. (6) Used in multiple television systems with different scanning ranges,
an image sensor having a number of pixels in the horizontal and vertical directions corresponding to a television system with the largest scanning range among the plurality of television systems, and a switch means for switching between the plurality of television systems, and the switch means: When a television system with a narrow scanning range is selected, unnecessary pixels in the vertical direction of the image sensor are skipped by controlling how addresses are given to the horizontal lines, and unnecessary pixels in the horizontal direction are read out by controlling the way addresses are given to the horizontal lines. An imaging device characterized by being compatible with television systems with different scanning ranges by controlling a shift operation and reading out at high speed. (7) In a television system with a narrow scanning range, charges of pixels in horizontal lines that are not read out are cleared by performing a reset operation during a vertical blanking period. The imaging device according to any one of Item 6.