JPH1057307A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To steadily protect an imaging unit including a solid imaging element even an imperfect contact has accidentally occurred in a Vout signal line of the solid imaging element. SOLUTION: On a circuit board 22 are applied an amplifying circuit composed of a diode D1 or D4, transistors Q1, Q2 and resistors R1, R2 and so on as well as a circuit part 31 of a protection circuit. Output terminal of the circuit board 22 is AC connected by means of a condenser C and a resistor RM, further connected through a pattern 27d to a coaxial cable 23f, which is to transfer amplified picture signal of the solid imaging element 20 to CCU.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly, to an image pickup apparatus having a characteristic in an image signal transmission portion.

[0002]

2. Description of the Related Art Conventionally, endoscopes capable of observing a site to be examined and performing various treatments by inserting an elongated insertion portion into a body cavity or the like have been widely used. In particular, in recent years, various electronic endoscopes having an image unit including a solid-state image sensor including an objective lens, a CCD, and the like, a circuit board connected to the solid-state image sensor, and the like have been proposed.

For example, in a video unit disclosed in Japanese Patent Application Laid-Open No. H5-269081, as shown in FIG. 6, a solid-state imaging device 100 has a φS (serial transfer) terminal, φAB ( An anti-blooming terminal, a φP (vertical transfer) terminal, a VDD (power supply) terminal, a SUB (ground) terminal, and a Vout (output) terminal. The circuit board 102 connected to the solid-state imaging device 100 is a circuit board in which an electronic component described later and an IC chip are arranged and connected on the board.

The above-mentioned φS, φAB,
The coaxial cables 103a, 103b,
103c are electrically connected to each other. A capacitor 104 is connected in parallel to each of a VDD terminal and a SUB terminal of the solid-state imaging device 100.
A coaxial cable 103d is electrically connected to the terminal, and a shield (not shown) formed at an end of the coaxial cable 103e is electrically connected to the SUB terminal. Further, the VDD terminal and the SUB terminal of the solid-state imaging device 100 are
They are connected to a power input terminal and a ground terminal of an IC chip 106 provided on the circuit board 102, respectively.

On the other hand, the Vout terminal of the solid-state imaging device 100 is connected to the input terminal of the IC chip 106.

The IC chip 106 has diodes D1 to D4, transistors Q1 and Q2, and a resistor R
An amplification circuit and a protection circuit composed of 1, R2 and RM are formed. The output terminal of the IC chip 106 is connected to a coaxial cable 103f, and the coaxial cable 103f is connected to the amplified solid-state imaging device 100.
Are transmitted to a camera control unit (CCU) not shown.

[0007]

However, in the prior art, as described above, the V
Since the out output signal is impedance-transformed by the transistors Q1 and Q2 and transmitted to the CCU via the coaxial cable 103f, if a contact failure such as a short-circuit occurs in the Vout signal line to GND, an overcurrent There is a problem that the power consumption of the transistors Q1 and Q2 and the cable matching resistor R3 exceeds the rated power consumption and may be destroyed.

That is, the endoscope and the CCU are usually connected via a connector. This connector is configured at a lower cost than the video unit including the solid-state imaging device.
For example, in the case of an inexpensive card edge type connector, the connection pin is deteriorated by the number of times of insertion and removal, and even when a relatively expensive connector is used, the endoscope is heat-sterilized due to its nature as a medical instrument. Since it is necessary, even if the connector is protected by the cap, water droplets and the like adhere to the pins of the connector before and after the heat sterilization treatment and deteriorate, thereby causing poor contact and causing the above-described problems. There is a fear.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple structure and ensures that an image unit including a solid-state image sensor can be reliably formed even when a contact failure occurs in a Vout signal line of the solid-state image sensor. It is an object to provide an imaging device that can be protected.

[0010]

According to the present invention, there is provided an image pickup apparatus including a solid-state image pickup device which is driven and controlled by drive control means and picks up an image of a subject, wherein the output signal of the solid-state image pickup device is AC-coupled. It has a part.

In the image pickup apparatus according to the present invention, by transmitting an output signal of the solid-state image pickup device to the drive control means via the AC coupling section, when a contact failure occurs in a signal line of Vout of the solid-state image pickup device. However, it is possible to reliably protect the video unit including the solid-state imaging device.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 relate to an embodiment of the present invention. FIG. 1 is a configuration diagram showing a configuration of an electronic endoscope as an image pickup apparatus. FIG. FIG. 3 is a configuration diagram showing a configuration of a video unit provided in FIG.
4 is a circuit diagram showing an equivalent circuit of the circuit unit of FIG. 1, FIG. 4 is a diagram showing a configuration of a modified example of a video unit in which the circuit unit of FIG. 2 is a hybrid IC, and FIG. FIG.

As shown in FIG. 1, an electronic endoscope 1 as an imaging apparatus according to the present embodiment has an elongated insertion portion 2 that can be inserted into a body cavity or the like. Part 3,
A bending portion 4 that can be bent and a flexible tube portion 5 having flexibility are provided. An operating portion 6 also serving as a grip portion is continuously provided on the rear end side of the insertion portion, and a universal cord 7 internally provided with a signal cable, a light guide fiber, and the like extends from the side of the operating portion 6. . The universal cord 7 is connected to a camera control via a connector 8 provided at the end.
The unit is connected to a unit (hereinafter, referred to as a CCU) 9.

Although not shown, the CCU 9 has a built-in light source device for supplying illumination light to the electronic endoscope 1, and the illumination light is supplied to the universal cord 7 and the insertion section 2.
The light is transmitted to the distal end portion 3 by a light guide fiber bundle (not shown) penetrating the inside, and is irradiated onto the subject.

The CCU 9 is a signal cable 1
The image signal of a subject imaged by a solid-state imaging device, for example, a CCD, which is provided in the distal end portion 3, is connected to the monitor 11 via the signal line 0, and the subject image is displayed on the monitor 11. It has become.

As shown in FIG. 2, in an image unit 15 provided in the distal end portion 3 of the electronic endoscope 1, a solid-state image pickup device 20 uses a not-shown image forming optical system to form a subject image on an image pickup surface. An image is formed, converted into an electric signal under the control of the CCU 9, and its output is output to the CCU 9 as an imaging signal. Terminal 2 as an example
1 is a φS (serial transfer) terminal, φAB (anti-blooming) terminal, φP (vertical transfer) terminal, VDD (power supply)
It has a terminal, a SUB (earth) terminal, and a Vout (output) terminal. The circuit board 22 connected to the terminal 21 of the solid-state imaging device 20 is a circuit board on which electronic components described later are arranged and connected.

The above φS, φAB, φ of the solid-state imaging device 20
Coaxial cables 23a, 23b, 23c
Are electrically connected to each other. A capacitor 24 is connected in parallel to each of the VDD terminal and the SUB terminal of the solid-state imaging device 20, a coaxial cable 23d is connected to the VDD terminal, and a coaxial cable 2 is connected to the SUB terminal.
Shield portions (not shown) formed at the ends of 3e are electrically connected to each other. Further, the solid-state imaging device 2
The 0 VDD terminal and the SUB terminal are connected to a power input terminal and a ground terminal provided on the circuit board 22, respectively.

The specifics around the wiring are as follows. That is, each electrode of the capacitor 24 is formed by two patterns 27a and 27b formed on the circuit board 22.
Are connected and fixed by soldering to the respective terminals of the VDD terminal and SUB terminal of the solid-state imaging device 20 as described above. The coaxial cable 23d is connected to the VDD terminal of the solid-state imaging device 20 by soldering and fixed, and the SUB terminal is connected to the coaxial cable 23e via a jumper wire 28.
Are connected to a shield part (not shown) formed at the end of the first part.

On the other hand, the Vout terminal of the solid-state
It is connected to an input terminal provided on the circuit board 22.

A specific wiring is connected to an input terminal via a jumper wire 29 having one end soldered to a Vout terminal of the solid-state imaging device 20 and a pattern 27c formed on the circuit board 22. The jumper wire 29 is soldered to the pattern 27c along the surface of the circuit board 22 where the capacitor 24 is not disposed, further passes through the cutout portion of the circuit board 22, and the other end.

On the circuit board 22, diodes D1 to D4, transistors Q1 and Q2 and a resistor R
A circuit section 31 of an amplifier circuit and a protection circuit composed of R1, R2 and the like is formed. And the circuit board 22
Is connected to a coaxial cable 23f via a pattern 27d, and the coaxial cable 23f transmits the amplified imaging signal of the solid-state imaging device 20 to the CCU 9. It has become.

Next, the operation of the embodiment constructed as described above will be described.

First, an equivalent circuit of an amplifier circuit and a protection circuit of a conventional imaging device (see FIG. 6) is as shown in FIG. Now, if it is assumed that Vcc = 15V R = 2.0KΩ RM = 47Ω DC bias from the solid-state imaging device (CCD) 9 = 8V, as shown in FIG.
In the connector receiver 9a, the Vout output from the solid-state imaging device 20 and the shield of the coaxial cable 23f are completely separated and insulated (circle A in the figure). When the shield of 23f is short-circuited and the Vout output is short-circuited to GND (circle B in the figure), the bias resistance R 'of the transistor Q2 becomes a parallel combined resistance of R and RM, and R' = R‖RM ≒ 46Ω. At this time, the input bias of the transistor Q2 is 7.4 VDC (= 8V-0.6V), and further, 0.6V between the base and the emitter of the transistor Q2.
If shifted, the DC bias of the emitter would be 6.
8VDC (= 7.4V-0.6V).

Therefore, the bias current I when the Vout output is short-circuited to GND is I = 6.8 V / 46Ω ≒ 150 mA, the power consumption of the transistor Q 2 ≒ 1.1 w, and the power consumption of the resistor RM ≒ 1 W. There is a risk of destruction.

However, in the imaging apparatus according to the present embodiment,
FIG. 3 shows an equivalent circuit of the circuit section 31 of the amplifier circuit and the protection circuit.
As shown in (a), the capacitor C is inserted into the Vout output, and the Vout output is transmitted to the CCU 9 by C coupling and AC coupling. Therefore, even when the Vout output is short-circuited to GND, a DC-like output is obtained. An overcurrent does not flow, and the destruction of the transistor Q2 and the resistor RM can be reliably prevented.

In the above-described embodiment, the circuit section 31 of the amplifier circuit and the protection circuit includes the diode D on the circuit board 22.
1 to D4, transistors Q1, Q2 and resistors R1, R2
Are arranged, but the present invention is not limited to this, and as shown in FIG.
A hybrid IC 41 in which 1, Q2 and resistors R1 and R2 are hybridized is provided on the circuit board 22, and an output terminal of the hybrid IC 41 is AC-coupled by a capacitor C and a resistor RM. You may make it transmit to CCU9.

Also, in the above embodiment, the image pickup apparatus is described as an electronic endoscope, but the present invention is not limited to this, and an endoscope apparatus having an external TV camera connected to the eyepiece may be used.

That is, as shown in FIG. 5, an endoscope device 51 as a modified example has an eyepiece 52a of a rigid endoscope 52.
, A TV camera-mounted endoscope 54 having an external TV camera 53 mounted thereon, a light source device 55 for supplying illumination light to the rigid endoscope 52, and a solid-state image pickup device (not shown) built in the external TV camera 53. CCU9 that performs signal processing on
A monitor 11 for displaying a video signal processed by the CCU 9.

In the external TV camera 53 of the endoscope device 51 as well, the Vout output of the built-in solid-state image pickup device is AC-coupled by the capacitor C and the resistor RM, so that the same effect as in the above embodiment can be obtained. Obtainable.

It is needless to say that the endoscope device 51 is not limited to a rigid endoscope, but may be a flexible endoscope having an eyepiece.

[Supplementary note] (Supplementary note 1) An image pickup apparatus provided with a solid-state image pickup device which is driven and controlled by drive control means and picks up an image of a subject, has an AC coupling section for AC-coupling the output signal of the solid-state image pickup device An imaging apparatus, wherein an output signal of the solid-state imaging device is transmitted to the drive control unit via the AC coupling unit.

(Supplementary note 2) In the supplementary note 1, a signal amplification circuit for amplifying an output signal of the solid-state imaging device is provided, and the AC coupling unit AC-couples an output of the signal amplification circuit. An imaging device according to any one of the preceding claims.

(Additional Item 3) The imaging apparatus according to additional item 2, wherein the signal amplification circuit is configured by a hybrid IC.

(Additional Item 4) The imaging device according to Additional Item 1, wherein the imaging device is an electronic endoscope having the solid-state imaging device built in a distal end portion of an insertion portion inserted into a body cavity. apparatus.

(Supplementary Note 5) The imaging device includes an endoscope having an insertion portion inserted into a body cavity, and the solid-state imaging device detachably provided on an eyepiece of the endoscope. 2. The imaging apparatus according to claim 1, wherein the imaging apparatus is an endoscope apparatus including an external camera.

[0037]

As described above, according to the imaging apparatus of the present invention, the output signal of the solid-state imaging device is transmitted to the drive control means via the AC coupling unit, so that the signal contacts the Vout signal line of the solid-state imaging device. Even if a defect occurs, there is an effect that the video unit including the solid-state imaging device can be reliably protected.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an electronic endoscope as an imaging device according to an embodiment of the present invention;

FIG. 2 is a configuration diagram showing a configuration of a video unit provided in a distal end portion of the electronic endoscope in FIG. 1;

FIG. 3 is a circuit diagram showing an equivalent circuit of the circuit unit in FIG. 2;

4 is a configuration diagram showing a configuration of a modified example of a video unit in which the circuit unit of FIG. 2 is a hybrid IC.

FIG. 5 is a configuration diagram showing a configuration of a modification of the imaging device of FIG. 1;

FIG. 6 is a configuration diagram showing a configuration of a video unit of a conventional electronic endoscope.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic endoscope 2 ... Insertion part 3 ... End part 4 ... Bending part 5 ... Flexible tube part 6 ... Operation part 7 ... Universal cord 8 ... Connector 9 ... CCU 10 ... Signal cable 11 ... Monitor 15 ... Video unit 20 ... Solid-state imaging device 21 ... Terminal 22 ... Circuit board 23a, 23b, 23c, 23d, 23e, 23f ... Coaxial cable 24 ... Capacitor 27a, 27b, 27c, 27d ... Pattern 28, 29 ... Jumper line 31 ... Circuit part

Claims (1)

[Claims] 1. An imaging apparatus including a solid-state imaging device that is driven and controlled by drive control means and captures an image of a subject, comprising: an AC coupling unit that performs AC coupling of an output signal of the solid-state imaging device; And transmitting an output signal of the solid-state imaging device to the drive control means.