JPH066671A - Light control circuit - Google Patents

Abstract

PURPOSE:To decrease consumption of a battery by lighting up a light only during video recording. CONSTITUTION:A low illuminance at the time of a signal level smaller than an electric signal subject to photoelectric conversion by a CCD image pickup element 3 is detected. A light control signal is outputted synchronously with video recording start through the operation of a video recording start stop switch 13 at the time of a low illuminance and the signal is stopped synchronously with the stop of video recording, then the signal is outputted for video recording only and the light control circuit is worked only for the video recording to apply a stable voltage to the light 19, which is lighted up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light control circuit, and more particularly, to a light control circuit which turns on a light in synchronization with the start of recording and turns off the light at the stop of recording.

[0002]

2. Description of the Related Art A conventional write control circuit will be described with reference to FIG. In the figure, 21 is a lens, 22 is an iris diaphragm, 23 is a CCD (Charge Coupled Device) image sensor, 24 is a CDS (Correlated Double Sampling), and 26 is an AGC (Automatic Gain).
Control) circuit, 27 is a signal processing circuit (encoder circuit), 28 is a detection circuit, 29 is a low illuminance detection circuit, 30 is a gate circuit, 31 is a switch, 32 is a power switch, 3
3 is a constant voltage control unit, 34 is a comparison error detection circuit, 35 is a reference voltage unit, 36 is a switch circuit, 37 is a feedback voltage unit, 3
8 is a light.

Light passes through a lens 21 and an iris diaphragm 22.
The amount of light is adjusted by the CCD image sensor 23, and is photoelectrically converted into an electric signal by the CCD image pickup device 23.
The C circuit 26 keeps the signal level constant, and the signal processing and encoder circuit 27 uses the VT as a camera Y (luminance) signal and a camera C (color) signal or a combined video signal.
Output to R section. The output signal of the CDS circuit 24 is detected by the iris circuit 25 to control the iris meter. When the amount of light incident on the lens decreases, the iris diaphragm 22 opens, and when it further decreases and exceeds full opening, the signal level decreases as the amount of light decreases. The electric signal at this time is detected by the detection circuit 28, and the low illuminance detection circuit 29 determines that the illuminance is low when it becomes a certain level or less, and outputs the determination signal a.

When the illuminance becomes low, the signal a in FIG.
Is "H". This output may be turned on / off via the gate circuit 30. Further, there is a case where the gate circuit 30 is not provided and the gate circuit 30 is directly connected to the switch 31. This is done with the switch 31 shown in FIG.
When the signal b-1 in (b) is connected, the previous low illuminance detected signal is connected and the signal b is output as a write control signal (hereinafter referred to as a write CTL signal). In this switch, the signal b-2 in FIG. 4 (c) has no connection, or is connected to GND, etc., and is in the OFF mode. The signal b-3 in FIG. 4 (d) may be connected to the Vcc line or the like to be in an ON mode in which it is constantly lit.

On the other hand, the light 38 is a battery (hereinafter, referred to as B
A constant voltage obtained by the constant voltage control unit 33 is applied from a power source such as ATT) via the power switch 32 to turn on the light. On the other hand, a stabilized power supply Vcc (eg, stabilized like the 5V line used in the camera circuit) is added to the comparison error detection circuit 34,
Further, the reference voltage section 35 of the comparison error detection circuit 34 is created based on the Vcc voltage. The output of the constant voltage control unit 33 is applied to the comparison error detection circuit 34 by the feedback voltage unit 37, and the constant voltage control unit 33 is driven by this output voltage. The write control circuit having such a configuration is a voltage stabilizing circuit, but a current control circuit may be added.

A switch circuit 36 is connected to the comparison error detection circuit 34 so that the constant voltage controller 33 can be stopped. The light CTL signal b is input to the switch circuit 36, and the switch circuit 36 operates according to the light CTL signal b to turn on / off the light. The low illuminance detection circuit 29
Although the output signal of the CDS circuit 24 is used for the above, the output signal of the AGC circuit 26 may be used.

As another conventional example, for example, Japanese Unexamined Patent Publication No.
There is a gate circuit as described in Japanese Patent No. 312454 which lights a light in synchronization with a low illumination condition and recording start. However, with this gate alone, when the light is turned on at the start of recording, the light becomes brighter and the low illumination condition disappears, and the light may go out or hunting may occur in which the light is turned on and off repeatedly. . Also, the subject condition may change due to panning during shooting while the light is on, and the low illuminance condition may temporarily change, and the light may not be turned on. 5A to 5D are timing charts of the light lighting at this time, the signal a shown in FIG. 5A is an output of low illuminance detection and is "H" when the illuminance is low. The signal b shown in FIG. 6B is a recording start / stop switch operation, and accordingly, the recording is being performed when the signal c shown in FIG. Then, the gate causes the signal d shown in FIG.
At that time, the light will be turned on. At this time, when all the low light conditions are being recorded, the light is turned on during the recording, but if the low light condition is changed during the recording as shown by the arrow mark, the light is also turned off. It will be.

[0008]

As described above, in the conventional light control circuit, the light is turned on or off by operating the light switch. Further, there is a device that detects low illuminance and turns on a light when the illuminance is low. In addition, there was a light which was turned on under low illumination condition and during recording. They turn off the lights when they are not needed to reduce battery consumption. However, during recording, the lighting conditions change temporarily due to panning during shooting, the low illumination conditions change, the low illumination conditions change due to the lighting of the light, and the delay due to the time constant in the iris circuit. However, there is a drawback in that the light may be turned on or off, and in some cases, blinking hunting may occur. Further, in the light control circuit, the Vcc line having a stabilized voltage is required to operate the circuit, and since the circuit is always active, waste current is consumed even when the light is not turned on. In addition, circuit connection patterns and connector wiring may increase. There is a problem in that current may also flow to the constant voltage control unit, and power is supplied through the power switch.

The present invention has been made in view of the above situation, and turns on a light in synchronization with the start of recording.
A light control circuit that turns off the light when recording is stopped to light the battery only during recording to reduce battery consumption and prevent malfunction due to changes in illuminance due to lighting of the light during recording. Is intended to provide.

[0010]

In order to achieve the above object, the present invention provides (1) a low illuminance detection circuit for determining that the illuminance is low when the amount of incident light is below a certain level, and a recording An operation unit for performing start / stop operation, a gate circuit for ANDing a signal from the low illuminance detection circuit and a signal for the recording start operation by the operation unit, and a light is turned on in synchronization with the recording start operation, It consists of a latch circuit that outputs a light control signal that turns off the light in synchronization with the recording stop operation.
(2) A switch circuit that is turned on by the write control signal, a reference voltage unit that uses the voltage of the write control signal as a reference voltage, a voltage from the reference voltage unit and a voltage supplied to the light are compared, It is characterized by comprising a constant voltage controller for controlling the voltage applied to the light to a constant voltage.

[0011]

In the low illuminance condition, the recording start operation causes both conditions to be satisfied in the gate circuit, and the light CTL signal is output. Further, the latch circuit provided after the gate circuit works in synchronization with the recording start / stop, so that the light is turned on at the recording start and turned off at the recording stop.
That is, even if the low illuminance condition changes during recording, the light is not turned off or turned on. Further, the Vcc line is not required, and the wiring of the connector and the like can be reduced. In addition, light C
Since there is no circuit current when there is no TL signal, power consumption can be reduced.

[0012]

Embodiments will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining an embodiment of a write control circuit according to the present invention, in which 1 is a lens,
2 is an iris diaphragm, 3 is a CCD image sensor, 4 is a CDS circuit, 5 is an iris circuit, 6 is an AGC circuit, 7 is a signal processing circuit (encoder circuit), 8 is a detection circuit, 9 is a low illuminance detection circuit, and 10 is Gate circuit, 11 is a toggle latch circuit,
Reference numeral 12 is a latch circuit, 13 is a recording start / stop switch, 14 is a switch circuit, 15 is a reference voltage section, 16 is a comparison error detection circuit, 17 is a feedback voltage section, 18 is a constant voltage control section, and 19 is a light. The CDS circuit is CC
This circuit uses the correlated double sampling method as a method of reducing the random noise of D (excluding the shot noise of the signal and the dark current). The main sources of random noise in CCD image sensors are
These are shot noise of signal current and dark current, reset noise at the time of signal detection, 1 / f noise of source follower and thermal noise. Further, the iris diaphragm is a diaphragm capable of adjusting the amount of light by continuously changing the diameter of the concentric opening by moving the movable adjusting unit.

The light passes through the lens 1, the amount of light is adjusted by the iris diaphragm 2, is photoelectrically converted into an electric signal by the CCD image pickup device 3, passes through the CDS circuit 4, and passes through the AGC circuit 6.
Then, the signal level is made constant by the signal processing and encoder circuit 7, and the signal is output to the VTR section as a camera Y (luminance) signal and a camera C (color) signal or a combined video signal. The output signal of the CDS circuit 4 is detected by the iris circuit 5 to control the iris meter. When the amount of light incident on the lens decreases, the iris diaphragm 2 opens and further decreases. After the full opening, the signal level decreases as the amount of light decreases. The electric signal at this time is detected by the detection circuit 8, and the low illuminance detection circuit 9 determines that the illuminance is low when the level is below a certain level, and outputs the determination signal a.

When the low illuminance detection circuit 9 detects that the illuminance is low, a low illuminance signal having the voltage of the signal a in FIG. 2A is output. When the recording start / stop switch 13 is operated, the voltage signal of the signal b in FIG. 2B is output. This is set to "H" during recording by the toggle latch circuit 11 in FIG.
The signal c of (c) is used as the signal c, and the gate circuit 10 AND-gates the low illuminance signal described above to obtain the signal d of FIG.
Signal. If it is left as it is, the light CTL signal may become "L" if the low illumination condition temporarily disappears due to light lighting or panning during recording, and hunting of the light lighting may occur. Circuit C is provided, and light C once turned to "H" during recording
The TL signal is maintained until the recording is stopped (paused), and is output as the write CTL signal of the signal e in FIG. 2 (e).

That is, when the illuminance is low, the recording is started.
It becomes "H" in synchronism with the start of recording by operating the stop switch, and the light CTL signal is always "L" when recording is stopped even if the low illuminance condition changes. Then, the write circuit is driven by this write CTL signal, and the write 1
9 is lit. The switch 31 described in the conventional example may be provided in the circuit shown in FIG. Gate circuit 10, toggle latch circuit 11, latch circuit 12,
The location of the code of the switch 31 may be processed by software of the microcomputer.

The write CTL signal is applied to the switch circuit 14 connected to the power supply voltage from the BATT or the like, and this switch circuit 14 is composed of a transistor circuit or the like. The switch circuit 14 is turned on when the write CTL signal is "H", and the comparison error detection circuit. 16 power sources are added. Further, since the write CTL signal is also connected to the reference voltage unit 15 and the power supply line Vcc in which the original circuit is stabilized is used,
Can be used as a reference voltage. Then, the voltage applied to the write is compared through the feedback voltage unit 17, the error is amplified, and the constant voltage control unit 18 controls the voltage to a constant voltage. The constant voltage controller 18 uses the switch circuit 14 to
If the comparison error detection circuit 16 does not operate, the circuit configuration is such that no current flows, and it is not necessary to provide a switch in the power supply line for the write control circuit. As described above, the power of the write control circuit is turned on by the write CTL signal, and it is also used as the reference voltage of the circuit. It is possible to apply a constant voltage to the light to turn on the light.
Further, a current limit may be added to the control circuit or a constant current control circuit may be operated.

[0017]

Since the present invention is constructed as described above, it has the following effects. (1) Effect corresponding to claim 1: The light is turned on in synchronization with the start of recording and turned off when the recording is stopped. It lights up only during recording, reducing battery consumption. Further, there is no malfunction due to a change in the low illuminance condition due to a change in illuminance due to lighting of a light during recording or a change in illuminance due to panning or the like. (2) Effect corresponding to claim 2: It is not necessary to connect a stabilized power supply line to operate the write control circuit. In addition, since the light control circuit is not always powered, unnecessary power consumption is eliminated.
There is no need for a power switch on the power line from ATT.

[Brief description of drawings]

FIG. 1 is a configuration diagram for explaining an embodiment of a write control circuit according to the present invention.

FIG. 2 is a diagram showing a timing chart of lighting of a light control circuit according to the present invention.

FIG. 3 is a configuration diagram of a conventional write control circuit.

FIG. 4 is a diagram showing a timing chart of a conventional write control circuit.

FIG. 5 is a diagram showing another timing chart of the conventional write control circuit.

[Explanation of symbols]

1 ... Lens, 2 ... Iris diaphragm, 3 ... CCD image sensor,
4 ... CDS circuit, 5 ... iris circuit, 6 ... AGC circuit,
7 ... Signal processing circuit (encoder circuit), 8 ... Detection circuit,
9 ... Low illuminance detection circuit, 10 ... Gate circuit, 11 ... Toggle latch circuit, 12 ... Latch circuit, 13 ... Recording start
Stop switch, 14 ... Switch circuit, 15 ... Reference voltage section, 16 ... Comparison error detection circuit, 17 ... Feedback voltage section, 1
8 ... Constant voltage control unit, 19 ... Light.

Claims (2)

[Claims] 1. A low illuminance detection circuit for determining that the illuminance is low when the amount of incident light falls below a certain level, an operation section for performing a recording start / stop operation, and a signal from the low illuminance detection circuit. A gate circuit for ANDing the signal by the recording start operation by the operation section, and a latch for outputting a light control signal for turning on the light in synchronization with the recording start operation and for turning off the light in synchronization with the recording stop operation A light control circuit comprising a circuit. 2. A switch circuit that is turned on by the write control signal, a reference voltage unit that uses the voltage of the write control signal as a reference voltage, and a voltage from the reference voltage unit and a voltage supplied to the light are compared. 2. The write control circuit according to claim 1, further comprising: a constant voltage control unit that controls a voltage applied to the light to a constant voltage.