JP2003038434A - Electronic endoscope device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic endoscope device capable of stably operating a CCD regardless of further reduction in the size of the CCD. SOLUTION: A detecting circuit for detecting the voltage of a substrate of the CCD and a charge extract circuit for extracting charges from the substrate of the CCD are set in a scope unit of the electronic endoscope device. When the substrate voltage detected by the detecting circuit is lowered to a designated threshold or less, the charge extract circuit is controlled to operate, and when the substrate voltage is not lowered to the designated threshold or less, the charge extract circuit is controlled not to operate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope apparatus, and more particularly, to drive control of an image pickup element arranged at the tip of an insertion portion of an electronic endoscope apparatus.

[0002]

2. Description of the Related Art Generally, an electronic endoscope apparatus has a scope unit having an insertion portion to be inserted into a body cavity or the like, and a scope unit detachably attachable to supply illumination light to the scope unit. And a processor unit that receives and processes an image signal from the unit to generate a video signal of a predetermined standard. An image sensor (CCD; Charge Cou) is attached to the tip of the insertion part of the scope unit.
The image signal of the subject image received by the CCD when the illumination light is radiated from the tip of the insertion part is transmitted via the signal cable arranged in the scope unit. Signal processing is performed in the base end portion of the scope unit and inside the processor unit, and output as a video signal of a predetermined standard from the processor unit to the monitor device.

On the other hand, recent CCDs have been provided with a VOD (vertical overflow drain) structure in order to prevent the occurrence of blooming and smear that may occur when receiving strong light, for example. In such a CCD,
The voltage (Vsub) applied to the substrate is internally generated using the power supply voltage (VDD) and is set to a positive voltage. It is possible to dispose of it in the substrate (substrate). Therefore, it is desired to use a CCD having such a VOD structure also in an electronic endoscope apparatus in order to obtain a good image.

[0004]

By the way, in the electronic endoscope apparatus used for medical purposes, it is required to reduce the diameter of the insertion portion in order to reduce the burden on the patient. Therefore, the CCD used in the electronic endoscope apparatus is required to be particularly downsized, and the CCD having the VOD structure is also downsized. A problem caused by the miniaturization of the CCD is that excess charges in the charge storage section cannot be stored in the substrate.

Especially when the CCD receives strong light,
The substrate potential may change remarkably due to the excessive charge being discarded to the substrate. If the substrate potential drops significantly in the CCD, a problem may occur in the charge transfer operation and the like, and a normal image may not be obtained.

The present invention has been made in view of such circumstances. That is, it is an object of the present invention to provide an electronic endoscope device that can stably operate a CCD even if the size of the CCD is reduced.

[0007]

Therefore, the invention according to claim 1 is an electronic endoscope apparatus which has a CCD at the tip of an insertion portion and generates a predetermined video signal based on an output signal from the CCD, A detection means for detecting the voltage of the substrate of the CCD and a charge extraction control means for operating so as to extract the charge from the substrate when the voltage of the substrate detected by the detection means falls below a predetermined threshold value. Prepare When the CCD receives strong light, it can be detected from the decrease in the substrate potential that the charge is excessively discarded from the charge storage portion of the CCD to the substrate. Therefore, when the electric potential of the substrate decreases, the electric charge extraction control means extracts electric charges from the substrate, so that the electric potential of the substrate can be kept normal and the operation of the CCD can be stabilized.

Here, the CCD may have a voltage generating circuit for internally generating a substrate voltage from the supplied power supply voltage (claim 2). The electronic endoscope apparatus of the present invention may further include a storage unit for storing a predetermined threshold value (claim 3).

According to a fourth aspect of the present invention, there is provided an electronic endoscope which has an insertion portion and a base end portion which is a connection portion to the processor unit, and which obtains an image signal of a subject from a CCD arranged at the tip of the insertion portion. In the scope unit for the apparatus, a detecting means for detecting the voltage of the substrate of the CCD and an operation for extracting electric charge from the substrate when the voltage of the substrate detected by the detecting means falls below a predetermined threshold value Charge withdrawal control means. CC
When D receives strong light, excessive charge is discarded from the charge storage section of the CCD to the substrate.
It can be detected from the decrease in the substrate potential.
Therefore, when the electric potential of the substrate decreases, the electric charge extraction control means extracts electric charges from the substrate, so that the electric potential of the substrate can be kept normal and the operation of the CCD can be stabilized.

Here, the CCD may have a voltage generating circuit for internally generating the substrate voltage from the supplied power supply voltage (claim 5). The scope unit of the present invention may further include a storage unit for storing a predetermined threshold value (claim 6).

[0011]

1 is a block diagram showing the overall configuration of a control system of an electronic endoscope apparatus 100 as an embodiment of the present invention. The electronic endoscope apparatus 100 supplies a scope unit 10 with an insertion portion 10a and a base end portion 10b to be inserted into a body cavity, supplies illumination light to the scope unit 10, and processes a signal obtained from the scope unit 10. Unit 50 for generating a video signal
It consists of and. The scope unit 10 is configured to be attachable to and detachable from the processor unit 50. In addition,
The image generated by the processor unit 50 is displayed on an external monitor (not shown) connected to the processor unit 50 via a connection cable.

In FIG. 1, the illumination light from the light source section 40 is inserted through the light guide 7 disposed inside the scope unit 10 into the insertion section 10a of the scope unit 10.
The subject is illuminated from the tip of the. An optical image of an illuminated object formed by an objective lens (not shown) provided at the tip of the insertion unit 10a of the scope unit 10 is received on the light receiving surface of a CCD (Charge Coupled Device) 2 and accumulated as an electric charge. And converted into an electric signal. The CCD 2 is an interline color CCD having a VOD structure.

The CCD 2 accumulates the light received by the light receiving surface as an electric charge and outputs an electric signal corresponding to the accumulated light quantity. The power supply voltage (VDD) and other drive signals for operating the CCD 2 are supplied from the CCD controller 9 to the CCD 2
Supplied to. By the control of the CCD control unit 9,
The image signal output from the CCD 2 is subjected to predetermined processing such as amplification and gamma correction in the CCD control unit 9, and then the video signal processing circuit 20 in the processor unit 50.
Entered in.

In the processor unit 50, the CCD
The signal from the control unit 9 includes a Y (luminance) component, RY (red-).
(Luminance) component and BY (blue-luminance) component digital signals, and the data of these components are Y memory 21, (RY) memory 22, and (B) which are image memories corresponding to the respective signals. -Y) Once stored in the memory 23.

The microcomputer 30 uses the timing signal generated by the timing circuit 31 to use the scope unit 10
Data communication with the side, control of the image memories 21-23, processing of input from a keyboard (not shown), and the like.

The data stored in the image memories 21-23 are read out at a predetermined timing under the control of the microcomputer 30 and input to the video processing circuit 25. The video processing circuit 25 synthesizes the image data of each component input from the image memories 21-23 to generate, for example, an NTSC standard composite video signal 26, an RGB separate signal 27, or the like. These video signals are sent to the monitor device. The power supply unit 45 supplies power such as the power supply voltage of the CCD 2 to the scope unit 10 side.

The aperture adjustment circuit 42 is a video signal processing circuit 2
Based on the signal of the brightness component generated by 0, the aperture of the diaphragm 41 is adjusted so that the brightness level of the image becomes a desired level.

FIG. 2 shows the CC inside the scope unit 10.
3 is a block diagram showing a detailed configuration of D2 and a CCD control unit 9. FIG. Details of the CCD2 control will be described with reference to FIG.
It should be noted that the CCD 2 here has a power supply voltage VDD of 15
It is a type of CCD that requires V and also requires a negative power supply such as a -8V power supply.

The power supply circuit 64 includes a processor unit 50.
Power supply (+ 15V, -8V) from the power supply unit 45 of
Is supplied to the CCD 2 at a predetermined input timing.
The CCD vertical clock driver 61 receives a vertical drive signal generated by a DSP (digital signal processor) 65 and outputs a vertical clock to the CCD 2. The CCD horizontal clock driver 62 is a DSP
Upon receiving the horizontal drive signal generated at 65, a horizontal clock is output to the CCD 2.

The microcomputer 67 uses D to adjust the color spectral characteristics of the CCD and the spectral characteristics of the light guide 7.
The white balance of the image signal generated in SP65 is adjusted. The data applied for the adjustment is stored in the memory (ROM) 66. As a result, the spectral characteristics of each scope unit are kept constant without variation. Further, the microcomputer 67 is the processor unit 50.
It is also connected to the side microcomputer 30 and has a function of performing data communication with the side microcomputer 30.

The image signal output from the CCD 2 is A /
The DSP 6 converts the digital signal by the D converter 63.
Input to 5. The DSP 65 subjects the input digital image signal to camera process processing such as blanking, clamping, white balance adjustment, and gamma correction, and outputs the image signal in the Y signal and C signal format to the processor unit 50 side. Output to.

FIG. 3A shows a VO used for the CCD 2.
The structure (cross-sectional view) of a general pixel portion of a CCD having a D structure is shown. In FIG. 3A, the voltage Vsub applied to the N substrate (substrate) portion is internally generated using the power supply voltage VDD (+ 15V) and set to a positive voltage. As a result, a potential well is formed in the charge storage section 2a and stable operation is obtained. The charges accumulated in the charge accumulation section 2a are then transferred to the vertical CCD register section 2b, further transferred to the horizontal CCD register section, and output from the signal output terminal 82 of the CCD 2.

FIG. 3 (b) is a diagram showing the potential distribution in the normal state in the AA 'direction of FIG. 3 (a). Note that FIG.
The vertical axis of (b) represents the potential, and the downward direction is the positive direction of the potential. When the charge in the charge storage section 2a becomes excessive, the overflowed electrons are discarded on the N substrate as indicated by arrow X in the figure. The substrate terminal 81 is a CCD
2 is connected to the N substrate inside, and the N substrate potential can be detected by detecting the voltage of the substrate terminal 81.

As shown in FIG. 2, the voltage of the substrate terminal (SUB) 81 is detected by the voltage detection circuit 68. The voltage detection circuit 68 includes, for example, an A / D converter that converts the voltage of the substrate terminal 81 into a digital value, and sends the detected voltage to the microcomputer 67 as digital data.

FIG. 4 is a circuit diagram showing the details of the charge extraction circuit 69 and its periphery. As shown in FIG. 4, the charge extraction circuit 69 includes capacitors C11 and C12 and a switch SW13, and the switch SW13 is turned on / off by a control signal from the microcomputer 67. C
Reference numeral 12 is a capacitor having a large capacity of 100 μF, for example, and can store a large amount of electric charge. C11 is, for example, a capacitor having a high frequency characteristic of 0.047 μF and capable of instantaneously extracting charges.

The microcomputer 67 keeps the switch SW13 off when the substrate terminal 81 voltage detected by the voltage detection circuit 68 is not lower than a predetermined threshold value. On the other hand, when the voltage of the substrate terminal 81 is equal to or lower than the predetermined threshold value, the microcomputer 67 determines that the switch SW1
3 is turned on, and the electric charges excessively discarded in the N substrate are extracted by the capacitors C11 and C12. It is assumed that this predetermined threshold value is stored in the memory (ROM) 66.

FIG. 5 is a flow chart showing the operation of extracting charges from the substrate of the CCD 2 which is executed by the microcomputer 67. First, the microcomputer 67 reads a predetermined threshold value (that is, D of the substrate) from the memory 66.
A value for determining whether or not the C potential is normal is read (S11). Next, the substrate potential detected by the voltage detection circuit 68 is acquired (S12). When the substrate potential is larger than the predetermined threshold value (S13: YE
S), because the substrate potential is normal, switch S13
Is kept off, and the substrate potential is measured again after a fixed time (for example, 1 second) (S14).

On the other hand, when the substrate potential is less than or equal to the predetermined threshold value (S13: NO), the substrate potential is lowered due to excess electric charge, and therefore the switch SW1.
3 is turned off → on → off, and the electric charge of the substrate is extracted by the electric charge extracting circuit 69 (S15). After step S15, the process returns to S12 again. In this way, even when excessive charges are accumulated on the substrate, the charges are extracted, so that the substrate is always kept at a normal potential, and therefore the stability of the operation of the CCD 2 is kept.

Now, a procedure of determining a predetermined threshold value to be stored in the memory 66, which is executed in the electronic endoscope apparatus 100, will be described with reference to the flowchart of FIG. The procedure shown in FIG. 6 is performed with the tip portion of the scope unit 10 darkened because it is necessary to measure the potential when the substrate potential is definitely normal. First, in step S21, it is determined whether or not to enter the substrate potential measurement mode, for example, by operating a keyboard (not shown) connected to the process unit 50 (S21). When entering the substrate potential measurement mode (S21: YE
S), the substrate potential is acquired from the voltage detection circuit 68 by the microcomputer 67 (S22). The substrate potential obtained at this time is a normal substrate potential when no charge overflow from the charge storage section in the CCD 2 occurs. Then, the threshold voltage based on the obtained substrate potential is stored in the memory 66. A voltage that is, for example, 2V lower than the obtained substrate potential can be used as a predetermined threshold value used in the flowchart of FIG. 5 (that is, for determining whether or not the substrate potential is normal).

As described above, by measuring the substrate potential in a normal state for each scope unit, determining a predetermined threshold value according to the measured potential, and storing it in the memory 66, it is possible to optimize each scope unit (CCD). It becomes possible to apply a threshold.

[0031]

As described above, according to the present invention, C
When the charge on the substrate of the CD is excessively discarded,
This charge can be extracted to the outside of the substrate, and the operation of the CCD can be stabilized. Therefore, it is possible to prevent the occurrence of blooming and smear and improve the quality of the image observed by the endoscope apparatus.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a control system of an electronic endoscope apparatus of the present invention.

FIG. 2 is a block diagram showing details of a control system in a scope unit of the electronic endoscope apparatus of the present invention.

3A and 3B are a cross-sectional view showing a general configuration of a pixel portion of a CCD arranged at the tip of an insertion portion of the scope unit shown in FIG. 2 and a diagram showing a potential distribution.

4 is a circuit diagram showing details of a charge extraction circuit in the scope unit of FIG. 2 and its periphery.

FIG. 5 is a flowchart showing an operation procedure of charge extraction.

FIG. 6 is a flowchart showing a procedure for determining a threshold value for determining whether or not the substrate potential is normal.

[Explanation of symbols]

2 CCD 10 Scope unit 50 processor units 64 power supply circuit 65 DSP 66 memory 67 Microcomputer 68 Voltage detection circuit 69 Electric charge extraction circuit 81 Substrate terminal 100 electronic endoscope system

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4C061 CC06 LL02 SS05                 5C022 AA09 AB31 AC42 AC69                 5C024 BX02 CX00 DX01 GY04 GZ04                       HX01

Claims (6)

[Claims] 1. An electronic endoscope apparatus having a CCD at the tip of an insertion portion and generating a predetermined video signal based on an output signal from the CCD, a detection means for detecting a voltage of a substrate of the CCD. An electronic endoscope, comprising: a charge extraction control unit that operates so as to extract charges from the substrate when the voltage of the substrate detected by the detection unit drops below a predetermined threshold value. Mirror device. 2. The electronic endoscope apparatus according to claim 1, wherein the CCD has a voltage generation circuit that internally generates a voltage of the substrate from a supplied power supply voltage. 3. The storage device according to claim 1, further comprising a storage unit for storing the predetermined threshold value.
The electronic endoscope apparatus according to item 1. 4. A C having an insertion portion and a base end portion which is a connection portion to the processor unit and arranged at the tip of the insertion portion.
In a scope unit for an electronic endoscopic device that obtains an image signal of a subject from a CD, a detection unit that detects the voltage of the substrate of the CCD, and the voltage of the substrate that is detected by the detection unit is below a predetermined threshold value. A charge extraction control unit that operates so as to extract charges from the substrate when the scope unit falls, and a scope unit. 5. The scope unit according to claim 4, wherein the CCD has a voltage generation circuit that internally generates a voltage of the substrate from a power supply voltage supplied. 6. The storage device according to claim 4, further comprising a storage unit for storing the predetermined threshold value.
Scope unit described in.