JPH04101582A - Cctv camera apparatus with electronic shutter - Google Patents

Abstract

PURPOSE:To control the speed of an electronic shutter of a solid state image pickup body by means of an inexpensive simple circuit without using a microcomputer by driving at variable speed the electronic shutter with the help of a timing signal obtained from a timing generator circuit which outputs a signal for controlling the speed of the electronic shutter. CONSTITUTION:A detector 5 detects the video level of a video signal in a signal processing circuit 4. A signal at the video level is integrated by a Millor integrator 11 and a inversion amplifier circuit 12, and the video level is converted into a DC level and then inverted. In a timer part 14, a pulse signal with a pulse width matching a voltage level is output by using the timing signal from a timing generator part 9 as a trigger pulse. When a detected video level is large, the pulse width of the pulse signal output from the timer part 14 is enlarged, and thus charge accumulated in a solid state image pickup element 2 is reduced. When the detected video level is small, the charge accumulated in the solid state image pickup element 2 is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to CCTV (C1osed C1rcuit).
The present invention relates to a CCTV camera device with an electronic shutter used in a Te1evision system, and more specifically to a CCTV camera device with an electronic shutter that reduces the cost of a shutter control circuit for the electronic shutter.

[Conventional Example] In recent years, electronic shutters have come to be attached to CCRV cameras used in CCTV systems, and the speed of the electronic shutter can now be arbitrarily varied.

A CCTV camera with an electronic shutter has the configuration shown in FIG. 3, for example. An optical lens 1 forms an image of an object on a solid-state image sensor (with an electronic shutter) 2, and the image of the object is converted into an electrical signal. a signal processing circuit 4 that processes the video signal from the imaging section 3 in a predetermined manner and converts it into a signal that can be input to a monitor device, and a shutter that variably controls the shutter speed of the solid-state imaging device 2. A control circuit is provided. As shown in the figure, the shutter control circuit includes a detector 5 that detects the video signal in the signal processing circuit 4 and detects the video level, and an A/D converter that converts the detected video level signal into a digital signal. D conversion section 6;
A control device (for example, a microcomputer) 7 compares this video level digital signal with reference data and outputs timing data for varying the speed of the electronic shutter according to the comparison result, and a control device (for example, a microcomputer) 7 that outputs timing data for varying the speed of the electronic shutter according to the comparison result. A D/A conversion unit 8 that converts into a control pulse, a timing generator unit 9 that outputs an electronic shutter speed control signal based on the timing of this control pulse, and a drive circuit that variably drives the electronic shutter speed based on this speed control signal. 10 are provided. Note that the control device 7 is not a microcomputer but, for example, a reference data output section 7 that outputs reference data.
a, a comparator 7b that compares this reference data with the detected video level, and a timing data output section 7c that outputs timing data for varying the speed of the electronic shutter according to the comparison result. There are some things.

In the solid-state image sensor 2, the charge generated for each horizontal synchronization signal is discharged by the waste pulse, and this charge is discharged during the stop period of the waste pulse. The number of pulses is determined by the speed control signal from the timing generator section 9. Therefore, when the image level is high, the pulse width of the control pulse from the control device 7 becomes large, and the number of charge pulses input to the solid-state image sensor 2 increases. Conversely, when the image level is small, the pulse width of the control pulse becomes small, and the number of charge pulses input to the solid-state image sensor 2 is reduced.

In this way, by controlling the number of charge discard pulses and automatically and continuously varying the speed of the electronic shutter, it is possible to make the image on the monitor uniform.

[Problems to be Solved by the Invention] However, since the above-mentioned CCTV camera device with an electronic shutter uses the A/D converter 6 that converts the video level into digital data, the speed conversion accuracy of the electronic shutter is low. Since it is determined by the number of bits of the A/D converter 6, if you try to increase the accuracy, you will have to use an A/D converter with a large number of processing bits, which is expensive. Even if it is used, there are problems in that the circuit scale is large and the cost is high.

This invention was made in view of the above problems, and its purpose is to provide an electronic shutter that can control the speed of the electronic shutter of a solid-state image pickup body using an inexpensive and simple circuit without using a microcomputer. CCTV with
The purpose of the present invention is to provide a camera device.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides an electronic shutter that processes a video signal captured by a CCTV camera with an electronic shutter and outputs a signal that can be input to a monitor device. The CCTV camera device includes a detector that detects the video signal and its video level, and a mirror that integrates the signal obtained by the detector to convert the video level into a DC level and inverts the video level. It operates with an integrating circuit and an inverting circuit, a limiter circuit that limits the DC level signal obtained by the mirror integrating circuit and inverting circuit within a predetermined level, and a trigger pulse synchronized with the vertical synchronization signal of the video signal. A timer circuit for outputting a pulse signal with a pulse width (1) corresponding to the voltage of the signal limited by the limiter circuit, and a timer circuit for varying the speed of the electronic shutter by changing the pulse width of the pulse signal obtained by the timer circuit. A switching circuit that determines the position of the control pulse, a timing generator circuit that outputs a signal to control the speed of the electronic shutter according to the control pulse, and a timing signal obtained from this timing generator circuit to control the speed of the electronic shutter. The gist of the present invention is to include a drive circuit that performs variable driving.

[Operation] With the above configuration, the video level of the video signal is converted to a DC level by the mirror integration circuit, and the timer circuit outputs a pulse signal with a pulse width (1) corresponding to the DC level. In this case, a low-cost IC circuit; The pulse width (1) is determined depending on the level. Then, the switching circuit outputs a control pulse having the pulse width as the pulse position to the timing generator section.

As a result, the timing generator section outputs a stop timing signal (shutter speed control signal) of the pulse, which dissipates the charge of the solid-state image sensor.

Therefore, when the video level is large, the pulse width (t) output from the timer circuit becomes large, so that the charge is discarded, the stop timing of the pulse is delayed, and the amount of charge accumulated in the solid-state image sensor is is reduced.

Furthermore, when the video level is small, the pulse width D) output from the timer circuit becomes small, so the charge is discarded and the stop timing of the pulse is accelerated, and the amount of charge accumulated in the solid-state image sensor is reduced. It happens a lot.

In this way, the shutter speed of the solid-state image sensor is automatically and continuously variably controlled in accordance with the detected image level.

[Embodiment] Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 and 2. In addition, in the figure, the same parts as in FIG. 3 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 1, this CCTV camera device with an electronic shutter includes a mirror integration circuit 11 that mirror-integrates the video level signal detected by the detector 5 and converts the video level into a DC level, and its level setting. A voltage generator 11a, an inverting amplifier circuit 12 that inverts and amplifies this mirror-integrated DC level signal, and a limiter circuit (transistor buffer circuit) that limits the inverted signal so that it does not swing to the O■ level. ) 13, a timer unit 14 that outputs a pulse signal with a predetermined pulse width (1) according to the voltage level of this limited signal, and a timing generator that uses the pulse width of this pulse signal as the position of a control pulse. A switching circuit 15 that outputs output to the section 9 is provided. Note that the Miller integration circuit 11 and the inverting amplifier circuit 12 are composed of operational amplifiers, and the limiter circuit 1
3 is composed of a pnp type transistor whose collector is grounded. Further, the timer section 14 is an IC circuit; 555, which operates with a trigger pulse synchronized with the vertical synchronization signal of the video signal, and outputs a pulse signal with a pulse width corresponding to the voltage level of the input signal. .

Next, the operation of the CCTV camera device with an electronic shutter having the above configuration will be explained with reference to the time chart shown in FIG.

First, it is assumed that an image is taken by the imaging unit 3, this video signal is processed in a predetermined manner by the signal processing circuit 4, and is input to a monitor device, etc., and the detector 5 detects the video signal from the signal processing circuit 4. It is assumed that the video level has been detected. Then, this video level signal is sent to the Miller integration circuit 1.
1 and an inverting amplifier circuit 12, the video level is converted to a DC level, and this DC level signal is inverted. This inverted signal is the limiter circuit 13
It is limited within a predetermined range so that the voltage does not become negative.

In addition, the timer section 14 uses the timing signal from the timing generator section 9 (a signal synchronized with the vertical synchronization signal shown in FIG. The pulse signal D) is output. Further, as shown in FIG. 2(C), the switching circuit 15 sets the pulse @(1) as a control pulse, and this control pulse is output to the timing generator section 9.

At this time, when the detected video level in the detector 5 is high, the voltage of the signal passed through the limiter circuit 13 becomes high, so the pulse @(t) of the pulse signal output from the timer section 14 becomes large. Therefore, the control pulse output from the switching circuit 15 is as shown in the figure (
It will be in the direction of the right arrow in C).

If the detected video level is small, limiter circuit 1
3, the voltage of the signal becomes low, so the pulse width (1) of the pulse signal output from the timer section 14 becomes small. Therefore, the control pulse output from the switching circuit 15 is in the direction of the left arrow in FIG.

As a result, as shown in FIG. 3(b), the timing generator section 9 outputs a speed control signal according to the control pulse, and this speed control signal controls the number of charge release pulses of the electronic shutter. be done. That is, when the detected video level is high, the pulse @(
Since t) is increased, the number of pulses for discharging the charge increases, and the charge accumulated in the solid-state image sensor 2 is reduced. Conversely, if the detected video level is small,
Since the pulse width (1) of the pulse signal outputted from the timer unit 14 is reduced, the number of pulses for ejecting the charge is reduced, and the amount of charge accumulated in the solid-state image sensor 2 is increased.

As described above, the electronic shutter device of the CCTV camera device with electronic shutter includes the above-mentioned detector 5, integrating circuit 11° inverting amplifier circuit 12, limiter circuit 15, timer section 14, switching circuit 15, timing generator section 9, and drive circuit 10. Since the circuit is constructed using a simple circuit, the electronic shutter speed can be automatically and continuously controlled with high accuracy without the need for the A/D converter shown in the conventional example, and without using a microcomputer. Moreover, cost reduction and size reduction can be achieved.

[Effects of the Invention] As explained above, the CCT with an electronic shutter of the present invention
According to the V camera device, there is a detector that detects the video level using an internally processed signal, a mirror integral of the video level signal, converting the video level to a DC level, and a detector that converts the video level signal into a DC level. an inverting integrating circuit and an inverting circuit; a limiter circuit that limits the inverted signal so that it does not swing to Ov; and a timer unit that outputs a pulse signal with a pulse width corresponding to the voltage of the limited signal.
A switching transistor circuit outputs a control pulse at a position corresponding to the pulse width of this pulse signal, a timing generator unit outputs a signal to control the speed of the electronic shutter using this control pulse, and a solid-state image sensor is driven by this speed control signal. Since the charge of the solid-state image sensor is discarded and the number of pulses is varied according to the image level, the speed of the electronic shutter can be automatically and continuously adjusted with high precision without using an A/D converter or a microcomputer. Since it can be varied and can be completed with a simple circuit, it has the effect of reducing costs and downsizing.

[Brief explanation of the drawing]

FIG. 1 shows a CC equipped with an electronic shutter showing an embodiment of the present invention.
A schematic partial block diagram of an RV camera device, FIG. 2 is a time chart diagram for explaining the operation of the CCTV camera device with an electronic shutter, and FIG. 3 is a schematic partial block diagram of a conventional CCTV camera device with an electronic shutter. It is. In the figure, 2 is a solid-state image sensor (with an electronic shutter), 4 is a signal processing circuit, 5 is a detector, 9 is a timing generator section, 10 is a drive circuit, 11 is a mirror integration circuit, 12 is an inverting amplifier circuit, and 13 is a limiter circuit, 14 is a timer section (IC
;555), 15 is a switching circuit. Patent applicant: Fujitsu General Co., Ltd. Agent: Patent attorney: Takuya Ohara

Claims (1)

[Claims] (1) In a CCTV camera device with an electronic shutter that processes a video signal captured by a CCTV camera with an electronic shutter and outputs a signal that can be input to a monitor device, the video signal is detected to detect the video level. a mirror integral circuit and an inverting circuit that perform mirror integration on the signal obtained by the detector, convert the image level to a direct current level, and invert the signal; A limiter circuit that limits a DC level signal within a predetermined level; and a limiter circuit that operates with a trigger pulse synchronized with the vertical synchronization signal of the video signal, and has a pulse width (t) according to the voltage of the signal limited by the limiter circuit. a timer circuit that outputs a pulse signal; a switching circuit that uses the pulse width of the pulse signal obtained by the timer circuit as a control pulse position for varying the speed of the electronic shutter; A CCTV with an electronic shutter, comprising: a timing generator circuit that outputs a signal for controlling the speed of the electronic shutter; and a drive circuit that variably drives the speed of the electronic shutter using the timing signal obtained by the timing generator circuit.
camera equipment.