JPH0244872A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To obtain a stable and good quality video by providing a cooling means to control the temperature of a solid-state image pickup element according to the output signal of a temperature detecting means provided on the chip of the solid-state image pickup element. CONSTITUTION:Voltage corresponding to the temperature capable of making a CCD type solid-state image pickup element (CCD) 2 operate by securing satisfactory image quality is set as reference voltage. Then, obtained difference voltage and the reference voltage are compared by a comparator 9, and when the difference voltage is larger than the reference voltage, the cooling device 3 is controlled so as to strengthen its cooling, and when the difference voltage is below the reference voltage, the cooling device 3 is controlled so as to keep constant voltage. Thus, the CCD 2 can be always maintained at constant temperature, and the stable and good quality video can be obtained.

Description

Detailed Description of the Invention (Object of the Invention) (Industrial Application Field) The present invention relates to a solid-state imaging device that converts an image into an electrical signal.

(Prior Art) The configuration of a conventional solid-state @image device (hereinafter referred to as a silver image device) is shown in FIG. The image input through the optical system is converted into an electrical signal by a solid-state image sensor (hereinafter referred to as an image sensor).
The output from the image sensor then undergoes predetermined signal processing to become an image signal.

At this time, the temperature of the image sensor itself increases due to long-time operation and ambient temperature. This temperature rise significantly increases noise due to dark current and fixed pattern noise generated in the image sensor, degrading image quality. For this reason, conventionally,
A temperature sensor is installed around the image sensor, and when the humidity detected by the sensor exceeds a reference temperature at which the noise generated by the image sensor does not pose a problem to the image quality, the image sensor is cooled down. The image quality achieved was as follows.

In this case, since the temperature sensor is not placed on the actual image sensor chip, the operating state of the image sensor itself cannot be affected.
The temperature is not detected.

The temperature detected by this temperature sensor 1) detects the average temperature of the entire silver image device. On the other hand, the temperature of the image sensor itself differs from the temperature detected by the temperature sensor because it is affected by heat generated by the image sensor itself as well as heat generated by the nearby drive circuit and other circuits. For this reason, the temperature detected by the temperature sensor and the actual temperature of the image sensor itself may differ significantly depending on the location of the temperature sensor and the external environment in which it is operated, resulting in the problem that constant image quality cannot always be obtained. .

(Problems to be Solved by the Invention) Conventional technology does not detect the temperature of the image sensor itself, so the temperature detected by the temperature sensor and the actual temperature may vary depending on the location of the temperature sensor within the image sensor and the external environment during operation. The temperature of the image sensor itself may vary significantly, and cooling controlled using this detected temperature has the problem that a constant image quality cannot always be obtained.

In the present invention, a temperature detection section is provided on the image sensor chip, and the detected temperature is used to control and cool the image sensor. Therefore, the temperature of the image sensor is kept constant under any operating conditions, and noise is kept below a certain level. It is possible. This enables a solid-state imaging device that always obtains a video signal of constant good image quality. The purpose is to provide

[Structure of the invention]

(Means for Solving the Problem) The present invention includes a temperature detection means provided on a chip of a pupil image element,
A solid-state imaging device is provided that includes a cooling means for controlling the temperature of an imaging element according to an output signal of the temperature detection means.

(Function) The temperature detection means provided on the depth of the image sensor constituting the present invention detects the temperature of the image sensor itself under any circumstances.

The cooling means, which is another component, cools the image sensor according to the output of the temperature detection means, and keeps the temperature of the image sensor below a certain temperature.

(Embodiments) First Embodiment An embodiment of the present invention is shown in FIG. Here, a CCD type solid-state image sensor (hereinafter referred to as CCD) will be explained.

The image input to C0D2 through optical system 1 is C0D2
It is converted into an electrical signal and output.

The signal output here is sent to the signal processing circuit 4 and simultaneously input to the LPF 5. l After removing the horizontal transfer frequency component included in the COD output, the signal input to the PF5 is transferred to the OB (optical black) section sample and hold circuit 6 and the empty section that samples and holds the empty feed portion where the light receiving photodiode signal of the CCD2 is not output. The sample and hold circuit 7 of the sending section is separately inputted, the oB section sample old output is delayed, and the phase is matched with the sample old output of the empty feeding section, and then subtracted from the output of the empty feeding section OB section. The output difference voltage obtained here is mostly a dark current component generated in the light-receiving photodiode, and is temperature dependent.

Utilizing this property, a voltage corresponding to a temperature at which the CCD 2 can be operated with sufficient image quality is set as the reference voltage.

Then, the obtained differential voltage and the reference voltage are compared with the comparator 9, and if the differential voltage is larger than the reference voltage, the cooling of the cooling device 3 is controlled to be strengthened, and if the differential voltage is below the reference voltage, the cooling device is controlled to be strengthened. The cooling device 3 is controlled to maintain a constant voltage.

By doing this, by keeping the CCD 2 at a constant temperature, it is possible to produce 1 q of stable, high-quality images.

In this embodiment, a CCD type solid-state image pickup device has been described, but the present invention can also be applied to an MO3 type solid-state image pickup device or a CPD type solid-state image pickup device.

Second Embodiment Another embodiment of the present invention is shown in FIG. Here, CCD
A type solid-state image sensor (hereinafter referred to as CCD-0) will be explained.

An image input from the optical system is converted into an electric signal by the CCD 12, and then passed through the signal processing circuit 14 to become a video signal.

A Pm junction is formed on a certain CCD 12 chip separately from the image sensor CCD 12. A constant current is passed through this Pm junction, and the voltage of the Pm junction is detected. This voltage is temperature dependent. Therefore, a temperature change is detected by this detection voltage change. Utilizing this property, the reference voltage is set to correspond to a temperature at which sufficient image quality can be ensured by the CCD 12. Thereafter, as in Example 1, the voltage detected at the Pm junction is compared with the reference voltage by the comparator 16, and if the detected voltage is greater than the reference voltage, control is performed to strengthen the cooling of the cooling device, and the detected voltage is If the voltage is below the reference voltage, the cooling device is controlled to maintain a constant temperature.

In this embodiment, a CCD type solid-state image sensor has been described, but the present invention can also be applied to an MO3 type solid-state image sensor or a CPD type solid-state image sensor.

(Effects of the Invention) As described above, according to the present invention, it is possible to keep the CCD at a constant temperature and obtain stable, high-quality images.

[Brief explanation of the drawing]

FIG. 1 does not show an embodiment of the cylinder 1 of the present invention, FIG. 2 shows a second embodiment 2, and FIG. 3 does not show a conventional example. 1, 11.21...Optical system, 2.12...CCD. 22...Image sensor, 3, 13.23...Cooling device, 9, 16.26...Comparator, 15...Pm
Junction, 10, 17...Reference voltage setting circuit, Agent: Patent attorney Noriyuki Chika, Yudo, Mitsuyuki Matsuyama

Claims (3)

[Claims] (1) A solid-state imaging device comprising a temperature detection means provided on a chip of a solid-state imaging device, and a cooling means for controlling the temperature of the solid-state imaging device according to an output signal of the temperature detection means. (2) The solid-state imaging device according to claim 1, wherein the temperature detection means uses an optical portion that shields the light-receiving photodiode from light. (3) The solid-state imaging device according to claim 1, wherein the temperature detection means uses a Pm junction formed on the same chip as the solid-state imaging device.