JP2007295105A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus that can suppress thermal effects on an imaging element. <P>SOLUTION: The imaging apparatus includes a printed circuit board 3; a CCD 1 mounted on one face of the printed circuit board 3; and an imaging element drive circuit 2, mounted on the other side of the printed circuit board 3 at a position that does not overlap the CCD 1, with the printed circuit board 3 in-between and driving the CCD 1. Furthermore, the imaging apparatus is provided with a printing pattern 31c which is formed on the printed circuit board 3, which connects the ground/power source pattern 31a of the CCD and the ground/power source pattern 31b of the imaging element drive circuit, and whose wiring width is smaller than the wiring width of the ground/power source pattern 31a of the CCD and the wiring width of the ground/power source pattern 31b of the imaging element drive circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an imaging device (such as a micro camera module) that is mounted on a mobile phone, a digital camera, or the like and that captures a still image or a moving image.

In a video camera or the like, the temperature in the housing rises due to its use environment or continuous use. As the temperature in the housing rises, the electronic components including the CCD may fail or the performance may deteriorate.
Further, in the CCD, the longer the exposure time, the greater the influence on the image quality due to thermal noise. In particular, when imaging in low light (such as at night), thermal noise may appear bright in the image.
In order to suppress the thermal influence on such electronic components, various heat dissipation methods (heat dissipation structures) have been proposed.

  For example, in the heat dissipation structure for a video camera described in Patent Document 1, a heat conductive rubber is interposed between each electronic component on each printed circuit board and each wall plate of the camera housing. The heat generated from each electronic component is transmitted to each wall plate via the heat conductive rubber, and further radiated to the outside of the camera casing. With this heat dissipation structure, there is no need to provide a vent in the camera casing or increase the outer dimensions of the camera casing.

JP 7-264450 A

Since the conventional image pickup apparatus is configured as described above, various heat dissipation such as providing a vent in the camera casing, increasing the outer dimension of the camera casing, or interposing a heat conductive rubber. It has a structure.
However, with the recent miniaturization of electronic devices such as mobile phones, the space that can be used for heat dissipation has decreased, and a conventional heat dissipation structure (such as vents, increased external dimensions, thermal conductive rubber Spaces for providing interventions and the like have been limited.
Therefore, there has been a problem that heat dissipation efficiency sufficient to ensure sufficient image quality by suppressing the thermal effect on electronic components, particularly the image pickup device (CCD), has not been obtained.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain an imaging apparatus that suppresses the thermal influence on the imaging element.

  The imaging device according to the present invention is mounted on a printed circuit board, an image sensor mounted on one surface of the printed circuit board, and on the other surface of the printed circuit board, at a position that does not overlap the image sensor across the printed circuit board, And an image sensor driving circuit for driving the image sensor.

  According to the present invention, since the image sensor and the image sensor drive circuit with a large amount of heat generation are arranged with the printed circuit board interposed therebetween, heat conduction from the image sensor drive circuit to the image sensor is suppressed, and the image sensor The temperature can be kept low. As a result, the occurrence of thermal noise in the image sensor is suppressed, so that an effect of improving the image quality can be obtained.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below. FIG. 1 is a block diagram showing a configuration example of an imaging apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a diagram showing an arrangement example when each configuration shown in FIG. 1 is mounted on a printed board. .
Next, the configuration of the imaging apparatus according to Embodiment 1 of the present invention will be described using FIGS.

As shown in FIG. 1, the imaging apparatus includes two integrated circuits (IC: Integrated Circuit) including an imaging element (hereinafter, CCD: Charge Coupled Devices) 1 and an imaging element driving circuit 2.
Further, the image sensor driving circuit 2 outputs a driving pulse to the CCD 1 and outputs a predetermined timing value to the driving circuit (hereinafter referred to as a driver) 21 that drives the CCD 1 at a predetermined timing and the driver 21. A timing generation circuit (hereinafter referred to as TG) 22 and an analog front end circuit (hereinafter referred to as AFE) 23 for A / D converting the output signal from the CCD 1.

As shown in FIG. 2, the CCD 1 is mounted on a surface (front surface) of the printed circuit board 3 at a position facing a lens (hereinafter, Lens) 4.
The image sensor drive circuit 2 is mounted on the opposite surface (back surface) of the printed circuit board 3 at a position shifted from a position facing the CCD 1 (a position not facing). In other words, the image sensor driving circuit 2 is mounted at a position that does not overlap the CCD 1 (position that does not face the Lens 4) with the printed circuit board 3 interposed therebetween.
Here, it is desirable that the CCD 1 and the image sensor driving circuit 2 are arranged so as not to overlap at all. However, at least, the IC chips in the package of both the CCD 1 and the image sensor driving circuit 2 are printed. It is necessary to arrange the substrates 3 so as not to overlap each other.

A thin print pattern (transmission line) 31 is provided as a wiring (power supply line, signal line, etc.) between the CCD 1 and the image sensor driving circuit 2. The print pattern 31 has a configuration in which a ground power pattern 31a (a part of the pattern in the figure) of the CCD and a ground power pattern 31b (a part of the pattern in the figure) of the image sensor driving circuit 2 are connected by the print pattern 31c. Have
Here, the gap between the ground power supply pattern 31a of the CCD and the ground power supply pattern 31b of the image sensor driving circuit is 0.5 mm or more. The pattern width of the print pattern 31c is preferably in the range of 0.5 to 1 mm, which is narrower than the pattern width of the ground power supply pattern 31a of the CCD and the ground power supply pattern 31b of the image sensor driving circuit.
Since the CCD 1 and the image sensor driving circuit 2 are mounted on the upper and lower surfaces of the printed circuit board 3, respectively, it is necessary to electrically connect them using through holes (via holes), inner layer patterns, or the like.

Next, the operation will be described.
First, the lens 4 forms an image of light from the subject on the light receiving surface of the CCD 1 through the diaphragm mechanism.
The CCD 1 is formed by alternately arranging several hundreds of thousands of pixels that are sensitive to red (R), green (G), and blue (B) light in a matrix, and charges the received light for each pixel. Is converted and stored, and the stored charge is output as an analog signal. The CCD 1 is driven by a drive pulse output from a driver 21 described later.

The TG 22 receives a clock signal (hereinafter referred to as CLK) and a control signal from the outside, generates a predetermined timing pulse (timing signal), and outputs it to the AFE 23 and the Driver 21.
Here, the CLK and control signal input to the TG 22 are output from an external circuit to which image data output from the imaging apparatus is input. CLK is a reference for a timing pulse generated by the TG 22. The TG 22 generates a plurality of timing pulses by a combination of CLK pulse count, frequency division, or multiplication.

The driver 21 outputs a driving pulse (driving signal) based on the timing pulse output from the TG 22, and drives the CCD 1 at a predetermined timing.
The AFE 23 converts the analog signal output from the CCD 1 into a digital signal (A / D conversion) at a predetermined timing based on the timing pulse output from the TG 22, and outputs the converted signal as image data to the outside.
Here, the AFE 23 performs A / D conversion on the analog signal output from the CCD 1 and outputs it in accordance with a predetermined timing at which the CCD 1 outputs an analog signal for each pixel.

Since the power consumed when the CCD 1 takes an image is generally very small, the heat generated by the power consumption hardly affects the generation of thermal noise.
On the other hand, since the driver 21 outputs a driving pulse to the CCD 1, its power consumption occupies most of the power consumption of all the imaging devices. Therefore, most of the heat generated by the imaging device is generated in the driver 21.

The heat generated in the image sensor driving circuit 2 is transferred to the top thereof via the printed circuit board 3. Here, as shown in FIG. 2, since the CCD 1 and the image sensor driving circuit 2 are arranged so as to be shifted from the opposing positions, most of the heat generated in the image sensor driving circuit 2 is directly transferred to the CCD 1. Without being discharged, it is discharged to the outside air in contact with the printed circuit board 3.
Therefore, the heat conduction to the CCD 1 is reduced, and the temperature rise in the same part is suppressed.

In addition, the thin print pattern 31 provided between the CCD 1 and the image sensor drive circuit 2 also reduces heat conduction through the print pattern formed of copper foil, and the temperature rise of the image sensor 1 is suppressed.
Specifically, as described above, when the print pattern 31 (especially the print pattern 31c) is thinned, the heat conduction resistance in the same portion is increased, so that the amount of heat transferred to the CCD 1 is reduced.

As described above, according to the first embodiment, since the CCD 1 and the image sensor driving circuit 2 are mounted at positions where they do not overlap with the printed circuit board 3 interposed therebetween, the temperature rise of the CCD 1 can be suppressed. As a result, the generation of thermal noise in the CCD 1 is reduced, so that an effect of preventing image quality deterioration can be obtained.
Also, by making the print pattern 31 finer, the temperature rise of the CCD 1 can be suppressed, and the same effect can be obtained.

It is the block diagram which showed the structural example of the imaging device which concerns on Embodiment 1 of this invention. It is the figure which showed the example of arrangement | positioning at the time of mounting each structure shown in FIG. 1 on a printed circuit board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 CCD (solid-state image sensor), 2 image sensor drive circuit, 3 printed circuit board, 4 lens (Lens), 21 drive circuit (Driver), 22 timing generation circuit (TG), 23 analog front end circuit (AFE), 31 print Pattern, 31a Ground power pattern of CCD, 31b Ground power pattern of image sensor driving circuit, 31c Print pattern.

Claims (3)

A printed circuit board,
An image sensor mounted on one surface of the printed circuit board;
An image pickup apparatus, comprising: an image pickup device driving circuit that is mounted on the other surface of the print substrate at a position that does not overlap the image pickup device across the print substrate and that drives the image pickup device.   Formed on the printed circuit board, connects the ground power pattern of the image sensor and the ground power pattern of the image sensor drive circuit, and has a wiring width larger than the ground power pattern of the image sensor and the ground power pattern of the image sensor drive circuit. The imaging apparatus according to claim 1, further comprising a narrow wiring pattern. A printed circuit board,
An image sensor mounted on the printed circuit board;
An image sensor driving circuit mounted on the printed circuit board and driving the image sensor;
Formed on the printed circuit board, connects the ground power pattern of the image sensor and the ground power pattern of the image sensor drive circuit, and has a wiring width larger than the ground power pattern of the image sensor and the ground power pattern of the image sensor drive circuit. An imaging device having a narrow wiring pattern.

Images