JP3208068B2 - Control method of cooling device for television camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for preventing dew condensation on an imaging surface of a television camera having an imaging device and a cooling device for controlling the temperature of the imaging device.

[0002]

[Prior art]

A television camera using a solid-state image pickup device such as a CCD as an image pickup device has a drawback that fixed noise due to dark current increases with an increase in temperature. In order to solve such a disadvantage, a cooling device such as a Peltier device or a radiator is incorporated to cool the imaging device. However, when the cooling device as described above is provided, in a high-temperature, high-humidity environment, dew condensation occurs on the incident surface of the imaging device, that is, the imaging surface, and there is a disadvantage that the screen is blurred or fogged. . Therefore, when dew condensation occurs on the imaging surface in this manner, it is necessary to wait until the dew condensation disappears naturally.
We had to wait more than an hour, which was extremely inconvenient.

[0004] In order to solve the above-mentioned drawback, it is conceivable to hermetically seal the periphery of the imaging surface of the imaging device.
In order to adjust the distance between the imaging surface and the exit surface of the optical system facing it, a wedge-shaped member is interposed between them, and after displacing the position, it is fixed with an adhesive. Therefore, the space between the imaging surface and the emission surface of the optical system cannot be hermetically sealed. Therefore, a Peltier device for dehumidification different from the Peltier device for cooling the imaging device is arranged near the imaging surface, and the temperature of the Peltier device for dehumidification is controlled to a lower temperature than the Peltier device for cooling the imaging device. Japanese Patent Application No. 6-133228 discloses, for example, Japanese Patent Application No. Hei.

[0005]

The above-described conventional dehumidifying method requires a Peltier element for dehumidification in addition to the Peltier element for cooling the imaging device, and has a drawback that the structure is complicated and the cost is high. Further, providing such two types of Peltier elements requires a relatively large space in the television camera, and there is a disadvantage that the television camera becomes large.

The present invention solves the above-mentioned drawbacks of the conventional television camera, and provides a cooling device for a television camera which can effectively prevent dew condensation on an imaging surface without providing a cooling device for dehumidification. It is intended to provide a control method.

[0007]

SUMMARY OF THE INVENTION The present invention comprises an imaging device,
In order to prevent dew condensation on the imaging surface of the television camera including the cooling device for cooling the imaging device, the cooling device is operated after a predetermined time has elapsed since the power of the television camera was turned on. Is what you do.
When performing such a control method according to the present invention, the operation of the cooling device is started when a predetermined time has elapsed since the power-on of the television camera, or after the power-on of the television camera. The operation of the cooling device can be started when the temperature of the imaging device rises to a predetermined temperature.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the configuration of an entire apparatus for implementing a method for controlling a cooling device of a television camera according to the present invention. + V is the positive terminal of the power supply of the television camera, and the negative terminal is grounded. The power supply positive terminal + V is connected via a power switch 11 to a timer time selection switch 13 provided in the timer 12. In the timer 12, the resistors 14 and 15 switched by the selection switch and the capacitor 16 constitute a charging circuit to set the timer time. These resistors 14, 15
A connection point 17 between the capacitor and the capacitor 16 is connected to the timer IC.
The power switch 11 is also connected to the emitter of the switching transistor 19.

The output terminal of the timer IC 18 provided in the timer 12 is connected to the input terminal of the D flip-flop 20.
The clock terminal of the D flip-flop 20 has a terminal 21
Supplies a vertical drive signal VD input through the. Also,
The inverted output terminal of the D flip-flop 20 is connected to the base of the switching transistor 19 described above. Further, the collector of the switching transistor 19 is connected to one end of a series circuit of the Peltier elements 22R, 22G and 22B, and the other end of the series circuit is grounded. In this example, a three-plate solid-state imaging device is used as the imaging device, and the above-described Peltier elements 22R, 22G, and 22B are directly or thermally conductive members to the solid-state imaging devices that capture red, green, and blue images, respectively. Attached through.

Next, the operation of this embodiment will be described. When the power is turned on by turning on the power switch 11, the switching transistor 19 is in the cutoff state and the Peltier element
Since 22R, 22G and 22B are disconnected from the power supply, no cooling action is started. After turning on the power switch 11,
When the time set by the timer 12 elapses, an output signal is generated from the timer and supplied to the D flip-flop 20. Thereafter, the D flip-flop is set at the timing when the vertical drive signal VD is supplied to the terminal 21, the inverted output signal is switched to low level, and the switching transistor 19
Becomes conductive. Therefore, the Peltier element 22R,
The current is supplied to the 22G and 22B from the power supply,
Cooling is started. In this example, the D flip-flop 20 is provided as described above, and power is supplied to the Peltier elements 22R, 22G, and 22B in synchronization with the vertical drive signal VD. The effect of noise mixing can be reduced.

As described above, according to the present invention, the Peltier elements 22R, 22G, and 22B are not operated immediately after the power switch 11 is turned on. Is turned on to start the operation of the Peltier element. During the elapse of the time set by the timer 12,
Since the temperature of the solid-state image sensor increases due to self-heating,
If the cooling capacity of the Peltier element is appropriately selected, the temperature of the solid-state imaging device does not drop below room temperature even when the operation of the Peltier element is started, so that dew condensation does not occur. In this example, the timer 12 is provided with two set times of 5 minutes and 10 minutes, and one of the set times can be selected by the selection switch 13. Therefore, the user can arbitrarily select a time during which dew condensation hardly occurs in accordance with the outside air temperature and humidity.

FIG. 2 shows changes in the temperature of the solid-state imaging device, the temperature of the television camera body, and the room temperature when the control method of the cooling device according to the present invention described above is carried out. Temperature of the solid-state imaging device and a camera body when the power switch 11 is turned on at time t ₀ is equal to the room temperature. Thereafter, the temperatures of the solid-state imaging device and the camera body gradually increase. Time t ₁ (10 minutes after power-on)
In the above, the temperature of the solid-state imaging device decreases by turning on the switching transistor 19 to start the operation of the Peltier devices 22R, 22G, and 22B, but by this time, the temperature of the solid-state imaging device has become higher than room temperature. Therefore, even when the Peltier element operates, the temperature of the solid-state imaging device does not become lower than room temperature. After that, Peltier device 22
By the action of R, 22G, and 22B, the temperatures of the solid-state imaging device and the camera body are controlled without excessively increasing.

FIG. 3 shows changes in the temperature and room temperature of the solid-state imaging device and the camera body when the conventional cooling device control method in which the operation of the Peltier element is started at the same time when the power is turned on. is there. When the Peltier element is operated at the same time when the power is turned on as described above, the temperature of the solid-state imaging device becomes lower than room temperature, so that dew condensation occurs. Since this condensation does not disappear unless the temperature of the solid-state imaging device becomes considerably higher than room temperature, it is necessary to wait for a considerably long time.

The present invention is not limited to the embodiment described above, but can be modified and modified in many ways. In the above-described embodiment, an analog timer is used as the timer, but a digital timer using the vertical drive signal VD as a clock signal can also be used. Further, in the above-described embodiment, the timer is provided, and the cooling device is operated when a preset time elapses after the power is turned on, but the temperature of the imaging device and the room temperature are detected by the temperature sensors, respectively.
After the power is turned on, the operation of the cooling device may be disclosed when the temperature of the imaging device becomes higher than the room temperature by a predetermined amount. In the above-described embodiment, a three-chip solid-state imaging device is used as an imaging device. However, other types of solid-state imaging devices such as a single-chip type or a four-chip type may be used. Further, the imaging device is not limited to a solid-state imaging device, but may be an imaging device using an imaging tube. Further, the cooling device is not limited to the Peltier element, and a cooling device using a heat pipe, a water-cooled cooling device, or the like can be used.

[0015]

As described above, according to the present invention, the cooling device for improving the characteristics of the imaging device of the television camera is not operated simultaneously with turning on the power to the television camera. Since the operation of the cooling device is started after the temperature of the device has risen, dew condensation on the imaging surface when the power is turned on can be effectively prevented. In this case, since there is no need to use a cooling device for dehumidification as in the related art, the configuration is simplified and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an example of an apparatus for implementing a method for controlling a cooling device of a television camera according to the present invention.

FIG. 2 is a graph showing a change in temperature of an imaging device in the method according to the present invention.

FIG. 3 is a graph showing a change in temperature of an imaging device according to a conventional method.

[Explanation of symbols]

 11 Power switch 12 Timer 13 Timer time selection switch 14, 15 Resistance 16 Capacitor 18 Timer IC 19 Switching transistor 20 D flip-flop 22R, 22G, 22B Peltier element

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-15636 (JP, A) JP-A-8-37612 (JP, A) JP-A-4-25288 (JP, A) JP-A-9-99 162379 (JP, A) JP-A-8-130668 (JP, A) JP-A-4-20183 (JP, A) JP-A-6-86129 (JP, A) JP-A-6-133228 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04N 5/222-5/257 G03B 17/55

Claims (1)

(57) [Claims] When preventing dew condensation on an imaging surface of a television camera including an imaging device and a cooling device for cooling the imaging device, one of two set times is set according to outside air temperature and humidity. A method for controlling a cooling device of a television camera, comprising: activating the cooling device after the selected set time has elapsed since the selected and turned on power of the television camera.