JPH02113680A - Solid state image pickup device - Google Patents

Abstract

PURPOSE:To reduce energy consumption by switching the turned on/off condition of a pulse signal in the vertical blanking period or horizontal blanking period of a solid state image pickup element by means of a pulse width modulating circuit. CONSTITUTION:The detecting signal of a temperature detector 4 is supplied to a temperature regulator 14, the temperature regulator 14 compares the inputted detecting signal with a set temperature, their difference is outputted as a control signal, and the control signal is supplied to a pulse width modulating circuit 15. The output signal of the pulse width modulating circuit 15 is supplied to a pulse driving circuit 16, and the output pulse of the pulse driving circuit 16 is supplied to a Peltier element 2, and the Peltier element 2 is driven. The pulse width modulating circuit 15 variably changes the pulse width according to the inputted control signal, and the turning on/off switching timing of the pulse signal is synchronized with the synchronizing signal from a synchronizing signal generating circuit 11. Thus, the energy consumption in the driving circuit of the temperature control element can be reduced, and the energy consumption can be reduced as a whole.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a solid-state imaging device using a solid-state imaging device such as a CCD, and particularly aims to improve a temperature control means for the solid-state imaging device. The present invention relates to a solid-state imaging device.

(Prior Art) Conventionally, a Vertier element is generally used to cool a solid-state image sensor. To drive this Vertier element, direct current is usually controlled and driven. At this time, an emitter follower is generally used, and when an attempt is made to control the intermediate level, a voltage drop occurs in the output transistor forming the emitter follower, and a power loss occurs in the drive circuit.

FIG. 7 shows an example of such a drive circuit, in which 71 is an emitter follower output transistor, 72 is a DC power supply,
Reference numeral 73 indicates a Vertier element serving as a load resistance, and reference numeral 74 indicates an input terminal. Now, the input voltage Ein is applied to the input terminal 'T-74.
When an input is applied, a voltage of Vot+t, which is equal to the voltage drop between the base and emitter of the transistor 7], is outputted, and a current of 2 flows through the l•rangestaff 1 and the Bertier element. At this time, a voltage drop of E o -V out occurs in the transistor 71, and I
A loss of (Eo-Vout) has occurred.

Furthermore, in the case of a multi-plate type imaging device, the number of cooling drive circuits required is equal to the number of image pickup elements, and for example, in the case of a three-plate type, three times as much power is required. Furthermore, the power loss in the output transistor is also tripled. Such power loss leads to an increase in battery capacity, which poses a big problem for portable video cameras and the like.

(Problems to be Solved by the Invention) As described above, conventionally, in order to drive a temperature control element such as a Beltier element using an emitter follower, there has been a problem in that the power loss in the driving circuit of the element becomes large.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide a solid-state imaging device that can reduce power loss in a drive circuit for a temperature control element and reduce power consumption. It's about doing.

[Structure of the Invention] (Means for Solving the Problems) The cutting method of the present invention is to drive a temperature control element such as a Beltier element that cools or heats a solid-state image sensor with a pulse signal, and to turn on/off the pulse signal. The objective is to synchronize the off-switching timing with the horizontal or vertical blanking period of the solid-state image sensor R chip.

That is, the present invention provides a solid-state imaging device including a temperature control element such as a Bertier element that cools or heats a solid-state imaging device, which includes a temperature detector that detects the temperature of the solid-state imaging device, and a temperature detected by the temperature detector. means for comparing the temperature with a set temperature and outputting the difference as a control signal; and a pulse width modulation circuit that varies the pulse width according to the control signal and outputs a pulse signal for driving the temperature control element. The pulse width modulation circuit is configured to switch the pulse signal on and off during a vertical blanking period or a horizontal blanking period of the solid-state image sensor.

The present invention also provides a multi-chip solid-state imaging device equipped with a temperature control element that cools or heats a plurality of solid-state imaging elements, including a means for selectively driving the temperature control element, and a means for selectively driving the temperature control element; A temperature detector for detecting each temperature, a means for comparing each detected temperature by the temperature detector with a set temperature and outputting the difference as a control signal, and a means for changing the pulse width by 11 J according to the control signal. , a pulse width modulation circuit is provided to output a pulse signal for driving the temperature control element, and the pulse width modulation circuit is configured to output a pulse signal for driving the temperature control element during the vertical blanking period or the horizontal blanking period of the solid-state image sensor. Perform on/off switching and synchronize within the horizontal blanking or vertical blanking period [7 and 11. lj division-C The temperature of the solid-state image sensor is controlled.

(Function) According to the present invention, power loss in the drive circuit can be reduced by pulse-driving a temperature control element such as a Bertier element, thereby reducing power consumption. In addition, since the pulse on/off switching timing is synchronized with the horizontal or vertical blanking of the solid-state image sensor, even if some voltage fluctuation occurs when the pulse signal is switched on/off, the solid-state image sensor will still be able to capture the image. It will not have an equally negative effect on the signal. In addition, in the case of multiple types, by driving each temperature control element in time division, cooling or heating of the solid-state image sensor can be performed efficiently, and the maximum power consumption can be reduced with the riJ function. Become.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a schematic configuration diagram showing a solid-state imaging device according to an embodiment of the invention. In the figure, reference numeral 1 denotes a solid-state image sensor, and a cooling surface of a Vertier element 2 for cooling the element 1 is provided on the back surface of the solid-state image sensor 1. Several rows of heat radiators 3 are arranged on the heat radiating surface of the Bertier element 2. Further, the solid-state imaging device 1 is provided with a temperature detector 4 for detecting the temperature of the device 1. Note that a CCD image sensor) is used as the solid-state image sensor. Further, the temperature detector 4 uses a platinum 411 hot body, a thermistor, a thermocouple, or the like.

A drive signal is input to the solid-state image sensor 1 from a CCD drive circuit]-2 which generates a CCD drive signal based on a synchronization signal from a synchronization signal generation circuit 11, and the solid-state image sensor 1 is driven by this drive signal.

The image signal of the solid-state image sensor 1 is then processed by a signal processing circuit 13.
and is output to an external circuit (not shown).

The detection signal of the temperature detector 4 is supplied to a temperature controller]4. The temperature regulator 14 compares the input detection signal with the set temperature and outputs the difference between them as a control signal, and the control signal is supplied to the pulse width modulation circuit 15. The output signal of the pulse width modulation circuit 15 is supplied to a pulse drive circuit 16, and the output pulse of this pulse drive circuit 6 is supplied to the Vertier element 2 to drive the Peltier cord 2.

The pulse width modulation circuit 15 is configured to vary the pulse width according to the input control signal, or the on/off switching timing of the pulse signal is synchronized with the synchronization signal from the synchronization signal generation circuit 11. .

Specifically, the pulse signal is switched on and off during the horizontal or vertical blanking period of the solid-state image sensor 1.

FIG. .beta. shows an example of the configuration of a pulse width modulation circuit 15, and this circuit 15 is connected to two input terminals 22 and 22 of a comparison type A-D converter.
23, an output terminal 24, etc. The input terminal 22 receives the control signal (No. 6) from the temperature controller 4, and the input terminal 2B receives the synchronization signal from the synchronization signal generation circuit 11, more specifically, the horizontal or vertical blanking signal. The A, -D converter 2 of the occasional comparison type is
The input control signal is A- using the synchronization signal as a clock pulse.
D-convert. This allows A to be adjusted according to the magnitude of the control signal.
The time required for D conversion changes and the output pulse width is modulated.

FIG. 3 shows input and output waveforms in the pulse width modulation circuit 5, where 31 is a synchronization signal, 32 is a control signal, and 33 is an output signal. The control signal is sampled every certain period, for example, every four clock periods, and the output is synchronized with the synchronization signal and set to a high level for a period corresponding to the magnitude of the input.

FIG. 4 is a diagram showing the principle of the pulse drive circuit 16.
1 is a DC power supply, 42 is a resistance of a Beltier element, 4': l,
44 indicates a switch element.

Generally, a switching transistor is used as the switch element. Here, switching transistors 4B, 4
4 is driven at AC-h, and is used without voltage drop, the power consumption in the drive circuit 6 is almost eliminated.

The Vertier element 2 can be used for both cooling and heating by changing the direction of the current. For example, if cooling is achieved by turning on the + side transistor 43, and heating is achieved by turning on the - side transistor 44, then by controlling the period during which each transistor 4344 is turned on, You can adjust the temperature. At this time, transistor 4 of drive circuit 16
3.44 is completely turned on or off, so all input power is applied to the Bertier element 2 and becomes energy for cooling or heating.

Thus, according to this embodiment, it is possible to drive the Bertier element 2 with a pulse voltage and cool the solid-state imaging probe.

Therefore, the output transistors 43 and 44 of the drive circuit 16
can be completely turned on or off, and all of the manually powered power can be consumed by the Beltier element 2, thereby eliminating unnecessary power consumption. In addition, since the pulse is turned on and off during the vertical blanking period of the solid-state image sensor, the driving voltage of the solid-state image sensor 1 changes due to the steep rise and fall of the pulse. Also, it is possible to prevent the adverse effects of noise on the imaging signal.

FIG. 5 is a block diagram showing a schematic configuration of a solid-state imaging device according to an embodiment of the invention as claimed in claim 2, and this embodiment cools an imaging element in a multi-plate solid-state imaging device.
It shows and has four characteristics. The solid-state imaging probe has three chips of different colors to be imaged: 5, a1, 51b, 51. c, each imaging floor T-
51a, -, 51-c have Bertier elements 52a, 52b, 5
2c and temperature detectors 54a, 54b and 54c are connected. In addition, figure) J<1. A heat radiator is attached to the heat radiating surface of the Bertier elements 52a to 52C.

The cooling control circuit 55 includes the temperature regulator 14. described in the previous embodiment. It consists of a pulse width modulation circuit 15, a pulse drive circuit 16, etc., and the cooling control circuit 55 is selectively supplied with a detection signal from one of the temperature detectors 54a, 54C through a changeover switch 57. Further, the drive pulse signal from the l9 control circuit 55 is selectively supplied to any of the Bertier elements 52a, 52c, 52a to 52c via the changeover switch 58. 58 is switched and driven by a switching timing circuit 56. The switching timing circuit 56 creates switching timing from the synchronization signal.

Further, although not shown in the drawings, as in the previous embodiment, drive circuits, signal processing circuits, etc. for the solid-state imaging cables 51a1 to 51c are provided in each solid-state imaging device.

As mentioned above, ccDv is used as the solid-state imaging probe. FIG. 6 shows the timing for controlling the cooling of each imaging floor r51a to 51c, and 61 is a vertical synchronization signal (VD).
, 62, 63. 64 are solid-state imaging probes 5] a1 to 51
This is the period (marked with X in the figure) during which the cooling of c is controlled. In this way, each v1j body image sensor 5]a, to 5]c is cooled for a period of approximately ]/3 from one vertical synchronizing signal to the next vertical synchronizing signal (1 field = 16.6 m5). It turns out. Furthermore, the pulse signal is switched on and off during the horizontal or vertical blanking period, as in the previous embodiment. In this case, each of the solid-state image sensors 51a to 5
]c is cooled only intermittently or repeatedly (7 cycles or the temperature is averaged quickly due to the heat capacity of the image sensor, so
No particular issues arise.

Here, one period is defined as one field, but it may be longer or shorter as long as the unit is a synchronizing signal.

Thus, according to this embodiment, as in the previous embodiment, the Bertier elements 52a1 to 52c can be driven with a pulse voltage, and the solid-state image sensors 51a to 51c can be cooled. Therefore, unnecessary power consumption in the cooling control circuit 55 can be eliminated, and power consumption can be reduced. In addition, the solid-state imaging probe 5 ]-a, ~
, 5]c during the horizontal or vertical blanking period, so as in the previous embodiment, noise mixing into the imaging signal due to pulse on/off is prevented.11. There are benefits to be gained.

Note that the present invention is not limited to each series of embodiments. For example, the temperature control element is not limited to a Beltier element, but may be any element that can be cooled or heated by energization. Furthermore, the pulse width modulation circuit is not limited to the configuration shown in FIG. Any configuration may be used as long as it is performed during the horizontal or vertical blanking period. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, when driving a temperature control element such as a Bertier element, the element is driven by a pulse signal and the on/off switching of the pulse signal is performed by the solid-state image sensor. Since this is carried out during the water 1' or vertical blanking period, the power consumption in the drive circuit of the temperature control element can be reduced, and the overall power consumption can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a solid-state imaging device according to an embodiment of the invention as claimed in claim 1, FIG. 2 is a diagram showing an example of the configuration of a pulse width modulation circuit in the device shown in FIG. 1, and FIG. FIG. 4 is a diagram showing the principle of the pulse drive circuit in the apparatus of FIG. 1, and FIG. 5 is a diagram showing an embodiment of the invention as claimed in claim 2. A schematic configuration diagram showing a solid-state imaging device; FIG. 6 is a diagram showing timing for controlling cooling of each imaging element in the device shown in FIG. 5; FIG. 7 is a diagram showing an example of a conventional Vertier element drive circuit. It is. 1.5], a, ~, 5]-c...Solid-state image sensor, 252
a, ~, 52c...Bertier element (temperature control element)
3... Heat sink, 4.54a to 54c - Temperature detector, 11... Synchronization signal generation circuit, 12... CCD drive circuit, 13... Signal processing circuit, 14... Temperature controller, 15 . . . Pulse width modulation circuit, 16 . . . Pulse drive circuit, 55 . . Cooling control circuit, 56 . . . Switching timing circuit, 57. 58 . . . Switch element. Applicant's agent Patent attorney Takehiko Suzue'Cp5 2 Figure 6134Figure 51a 2a t, Figure 35

Claims (3)

[Claims] (1) a solid-state image sensor, a temperature control element provided in contact with the solid-state image sensor to control the temperature of the solid-state image sensor, and a temperature detector that detects the temperature of the solid-state image sensor;
Comparing the temperature detected by the temperature detector and the set temperature,
comprising means for outputting these differences as a control signal, and a pulse width modulation circuit that varies the pulse width according to the control signal and outputs a pulse signal for driving the temperature control element, A solid-state imaging device, wherein the modulation circuit switches the pulse signal on and off during a vertical blanking period or a horizontal blanking period of the solid-state imaging device. (2) A plurality of solid-state image sensors, a temperature control element that is provided in contact with each of these solid-state image sensors and controls the temperature of each of the solid-state image sensors, and selectively drives these temperature control elements. means, a temperature detector for respectively detecting the temperature of the solid-state image sensor, means for comparing each detected temperature by the temperature detector with a set temperature and outputting the difference as a control signal; a pulse width modulation circuit that outputs a pulse signal for driving the temperature control element by varying the pulse width accordingly; The solid-state imaging device is characterized in that the pulse signal is switched on and off during the ranking period, and the temperature of the solid-state imaging device is controlled in a time-sharing manner synchronized with the horizontal blanking period or the vertical blanking period. Device. (3) The solid-state imaging device according to claim 1 or 2, wherein the temperature control element is a Peltier element.