JP2012228451A - Electronic endoscope apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic endoscope apparatus capable of appropriate correlation double sampling processing even when a distal end of an insertion part of the endoscope is used in various temperature ranges.SOLUTION: The electronic endoscope apparatus 1 includes: a CCD 22; a temperature sensor 24 for detecting the temperature of the distal end 11a; a correlation double sampling section 51 provided for a body portion 12 to take out a signal component from an image signal output from the CCD 22; a timing generator 55 for generating a sample hold signal to operate the correlation double sampling section 51 and a drive pulse signal to drive the CCD 22; and a CPU 44 for adjusting, based on the temperature detected by the temperature sensor 24, the timing of the sample hold signal or drive pulse signal generated by the timing generator 55.

Description

  The present invention relates to an electronic endoscope apparatus, which is an electronic endoscope apparatus that can appropriately perform correlated double sampling processing according to the temperature of the use environment of the distal end portion of the insertion portion.

Conventionally, endoscope apparatuses have been widely used for various examinations in the medical field and the industrial field. The endoscope apparatus includes an elongated insertion portion, a main body portion, and a monitor provided on or connected to the main body portion.
In the industrial field, an endoscope apparatus may be used in various temperature environments, for example, inspection of an outdoor building below freezing point, inspection of a jet engine exceeding 100 ° C., and the like.

  A user who is an inspector inserts an elongated insertion part into an inspection object, and displays or stores an image of an examination part imaged by an imaging element such as a CCD provided at the distal end of the insertion part on a monitor The test is performed by storing the data in the memory.

  The image sensor provided at the distal end of the insertion unit is driven by a drive circuit in the main body, and the image signal output from the image sensor is correlated with the image signal processing unit in the main body for noise removal and the like. A correlated double sampling process is performed in the sampling circuit.

  By the way, the operation timing of an electronic component including a semiconductor device changes according to the temperature of the use environment. Therefore, a technique for delaying the operation timing of the drive circuit of the image sensor in accordance with the temperature of the digital camera is proposed in order to appropriately process the image signal from the image sensor (for example, Patent Document 1). reference).

JP 2001-54027 A

  However, since the above-mentioned proposal assumes a general digital camera, the signal waveform becomes dull because the use environment such as an endoscope apparatus and the image pickup device at the tip and the main body are connected by a long signal line. The change in the operation timing due to the ease is not taken into consideration.

  In the endoscope apparatus, since the long insertion portion is used in a wide temperature environment, the temperature of the distal end portion varies greatly. For example, even if the temperature inside the jet engine, which is one of the inspection targets, is 100 ° C., the temperature of the main body of the endoscope apparatus does not change as much as the tip. Furthermore, the length of the insertion part of the endoscope apparatus is 10 m or more in some cases. For this reason, the waveform of the image signal from the image sensor tends to be dull due to a long signal line. Since the endoscope apparatus has a different feeling of use from a general digital camera in this way, the technology according to the above-described proposal cannot be used as it is for the endoscope apparatus.

  Therefore, the present invention provides an electronic endoscopic apparatus having an elongated insertion portion, in which correlated double sampling processing is appropriately performed even when the distal end portion of the insertion portion of the endoscope is used in various temperature ranges. An object of the present invention is to provide an electronic endoscope apparatus that can be used.

  According to one aspect of the present invention, an imaging device provided at a distal end portion of an endoscope insertion portion, a first temperature detection portion that detects a first temperature of the distal end portion, and the endoscope insertion portion Is provided in the main body to which the base end of the image sensor is connected, and a correlated double sampling unit for extracting a signal component from the image signal output from the image sensor, and an electric signal is transmitted between the front end and the main body. And a timing generator for generating a sample and hold signal for operating the correlated double sampling unit and a driving pulse signal for driving the image sensor, and the first temperature. A timing adjustment unit for adjusting the timing of the sample hold signal or the drive pulse signal generated by the timing generation unit based on the first temperature detected by the detection unit; It is possible to provide an electronic endoscope apparatus.

  According to the present invention, in an electronic endoscope apparatus having an elongated insertion portion, even when the distal end portion of the insertion portion of the endoscope is used in various temperature ranges, the correlated double sampling process is appropriately performed. An electronic endoscope apparatus that can be realized can be realized.

1 is a configuration diagram showing a configuration of an endoscope apparatus according to a first embodiment of the present invention. . FIG. 4 is a circuit diagram of a circuit 23a for shaping the waveform of a drive pulse signal (RG, H1, H2) supplied to the CCD 22 according to the first embodiment of the present invention. It is a figure which shows the example of the correction value table of the CDS timing stored in EPROM45 concerning the 1st Embodiment of this invention. 4 is a timing chart of a drive pulse signal, an image signal, and a sample hold signal input to a CCD 22 with respect to a clock signal CK according to the first embodiment of the present invention. It is a flowchart which shows the example of the flow of a correction process of the timing signal of CPU44 concerning the 1st Embodiment of this invention. It is a figure which shows the example of the correction value table of the timing of the drive pulse signal (RG, H1, H2) stored in EPROM45 concerning the 1st Embodiment of this invention. It is a flowchart which shows the example of the flow of a correction process of the timing signal of CPU44 based on the modification 1 of the 1st Embodiment of this invention. It is a circuit diagram of the circuit 23b which supplies the drive pulse signal (RG, H1, H2) based on the modification 2 of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the endoscope apparatus concerning the 2nd Embodiment of this invention. It is a figure which shows the example of the correction value table of the CDS timing stored in EPROM45 concerning the 2nd Embodiment of this invention. It is a figure which shows the example of the correction value table of the timing of the drive pulse signal (RG, H1, H2) stored in EPROM45 concerning the 2nd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a configuration diagram showing a configuration of an endoscope apparatus according to the present embodiment. The endoscope apparatus 1 includes an elongated insertion portion 11, a main body portion 12 to which the proximal end of the insertion portion 11 is connected, and a liquid crystal display device (hereinafter referred to as LCD) 13 that is a display portion connected to the main body portion 12. Is an electronic endoscope apparatus configured to include: The user who is an inspector can inspect by inserting the distal end portion of the insertion portion 11 into the inspection target apparatus and displaying an endoscopic image of the inspection site on the LCD 13. The endoscopic image can also be recorded on a recording medium 14 that can be attached to and detached from the main body 12.
1, the insertion portion 11 may be connected by a connector 15 of the main body portion 12 so as to be detachable from the main body portion 12.
Further, in this embodiment, the connector 15 is separated from the insertion portion 11 at the end of the preamplifier 41 and the timing generation circuit 55, which will be described later. You may be able to do it. For example, a configuration in which an analog front end unit 2 and a timing generation circuit 55 (a part of the field programmable gate array 43) described later are inserted on the insertion unit 11 side may be employed. According to such a configuration, all the elements that generate timing deviation can be concentrated on the insertion portion 11 side. Therefore, when the attachment / detachment system is realized, the combination adjustment on the insertion portion 11 side and the main body portion 12 side is reduced. be able to.

  A plurality (two in FIG. 1) of light emitting diodes (hereinafter referred to as LEDs) 21 as illumination units are provided at the distal end portion 11a of the insertion portion 11. The LED 21 is disposed around an observation window (not shown). An objective optical system (not shown) is disposed inside the observation window, and a CCD 22 that is an image sensor is disposed at the focal position of the objective optical system. That is, the CCD 22 is an image sensor provided at the distal end portion 11 a of the insertion portion 11.

  The CCD 22 is connected to the main body 12 via a waveform shaping circuit 23. The waveform shaping circuit 23 includes a circuit for shaping and supplying the drive pulse signals (RG, H1, H2) to the CCD 22 and a buffer circuit for impedance-converting the image signal from the CCD 22.

  FIG. 2 is a circuit diagram of the circuit 23a for shaping the waveform of the drive pulse signal (RG, H1, H2) supplied to the CCD 22. The drive pulse signals (RG, H1, H2) from the main body 12 are input to the amplifier AMP via the comparators CM that are compared with respective predetermined thresholds, so that each drive pulse whose waveform is shaped is supplied to the CCD 22. The

  Furthermore, a temperature sensor 24 for detecting the temperature of the distal end portion 11 a is provided in the vicinity of the CCD 22 at the distal end portion 11 a of the insertion portion 11. The temperature sensor 24 as the temperature detection unit is, for example, a thermistor. The temperature sensor 14 is mounted on, for example, a circuit board on which the waveform shaping circuit 23 is mounted from the viewpoint of ease of attachment and fixing.

The main body 12 includes a camera control unit (hereinafter referred to as CCU) 31, a recording / playback unit 32, an LED drive circuit 33, an LCD driver circuit 34, an operation unit 35, and an image signal output terminal 36.
The CCU 31 is a preamplifier 41, an analog front end unit (hereinafter referred to as AFE) 42, a field programmable gate array (hereinafter referred to as FPGA) 43, a central processing unit (hereinafter referred to as CPU) 44, and a rewritable nonvolatile memory. It has EPROM45.

The preamplifier 41 is a circuit that amplifies the image signal from the CCD 22 received via the buffer circuit of the waveform shaping circuit 23.
The AFE 42 includes a correlated double sampling circuit (hereinafter referred to as a CDS unit) 51, an auto gain adjustment circuit (hereinafter referred to as an AGC unit) 52, and an analog-digital conversion circuit (hereinafter referred to as an A / D unit) 53. The CDS unit 51 receives the image signal from the preamplifier 41, performs correlated double sampling processing for noise removal based on the sample hold signal (SH 1, SH 2), and outputs it to the AGC unit 52. That is, the CDS unit 51 is a correlated double sampling unit that is provided in the main body unit 12 to which the proximal end of the insertion unit 11 is connected and extracts a signal component from the image signal output from the CCD 22.

  The AGC unit 52 adjusts the gain of the image signal from the CDS unit 51 and outputs it to the A / D unit 53. The A / D unit 53 converts an image signal that is an analog signal into a digital signal and supplies the digital signal to the FPGA 43.

  The FPGA 43 includes a video signal processing unit 54 and a timing generation circuit (hereinafter referred to as a TG unit) 55. The video signal processing unit 54 processes the image signal from the AFE 42 based on the control signal from the CPU 44 and outputs it to the LCD driver circuit 34 and the recording / reproducing unit 32. The video signal processing unit 54 supplies the live image signal from the CCD 22 to the LCD driver circuit 34. The video signal processing unit 54 converts the image signal from the CCD 22 into a general-purpose image signal and outputs the image signal to the recording / reproducing unit 32.

  The TG unit 55 generates and outputs various timing pulse signals under the control of the CPU 44. Specifically, the TG unit 55 generates and outputs various drive signals (RG, H1, H2, V1 to V6) to the CCD 22. Further, the TG unit 55 also generates and outputs timing pulse signals (SH1, SH2, ADCK) to the CDS unit 51 and the A / D unit 53. The CDS unit 51 is driven by SH1 and SH2 which are two types of sample and hold pulse signals. The TG unit 55 also generates and outputs various timing pulse signals TP in the FPGA 43. That is, the TG unit 55 is provided in the main body unit 12 and constitutes a timing generation unit that generates a sample hold signal for operating the CDS unit 51 and a drive pulse signal for driving the CCD 22.

  Further, the TG unit 55 generates a plurality of timing pulse signals as described above, and is configured to be able to adjust the timing of each timing pulse signal in accordance with a correction instruction from the CPU 44, as will be described later. Has been.

  The CPU 44 is provided in the main body unit 12 and controls various circuits in the CCU 1 and the recording / reproducing unit 32 based on instructions from the operation unit 35 including a switch operated by the user. Further, here, the CPU 44 includes an A / D unit 56. The A / D unit 56 converts an analog voltage signal from the temperature sensor 24 of the tip end part 11 a into a digital signal, and supplies digital data regarding the temperature of the tip end part 11 a to the CPU 44. The CPU 44 calculates the temperature from the digital data from the temperature sensor 24.

  The recording / playback unit 32 includes an image processing LSI 58. The image processing LSI 58 encodes the image signal from the video signal processing unit 54 on the basis of the control signal from the CPU 44, records it on the recording medium 14 via the connector 59, and is recorded on the recording medium 14. This is a circuit that reads out the endoscopic image, decodes and reproduces it, and outputs it to the LCD 13 via the LCD driver circuit 34. The image processing LSI 58 can output an image signal via the image signal output terminal 36. The image processing LSI 58 includes a scaling process for converting the image size, and outputs various image signals in an analog VGA format, SDI format, VBS (composite video), S video signal, DVI format, and the like via the image signal output terminal 36. It is possible.

  Instead of the temperature sensor 24 described above, a temperature detection unit that detects the temperature of the tip 11a from the DC component of the impedance conversion element as disclosed in Japanese Patent Application Laid-Open No. 2007-125111 may be used.

  The EPROM 45 is a memory that stores a correction value table that stores correction value data to be described later. The correction value table stores the phase adjustment time or pulse width adjustment information of various pulses generated by the TG unit 55 corresponding to the temperature data of the temperature sensor 24. The CPU 44 reads the phase adjustment value or the pulse width adjustment value from the EPROM 45 from the temperature data of the temperature sensor 24 with reference to the correction value table of the EPROM 45, and outputs it to the TG unit 55 as correction value data. That is, the CPU 44 and the TG unit 55 refer to the table storing the correction value for correcting the timing, and use the correction value corresponding to the temperature read from the table to determine the timing of the sample hold signal or the drive pulse signal. A timing adjustment unit for adjusting the is configured.

  Further, the CPU 44 displays the temperature data of the temperature sensor 24 as temperature information on the screen of the LCD 13, and reduces the brightness, color density, random noise, etc. of the video displayed according to the temperature data. For this purpose, the temperature data can be transmitted to the video signal processing unit 54 in the FPGA 43 and the image processing LSI 58 in the subsequent stage by communication. Therefore, the CPU 44 and the LCD 13 constitute a temperature display unit that displays the temperature of the distal end portion 11a.

  FIG. 3 is a diagram illustrating an example of a CDS timing correction value table stored in the EPROM 45. The correction value table TBL1 stores the correction values of the timing pulse signals SH1, SH2, ADCK to the CDS unit 51 and the A / D unit 53, corresponding to the temperature T1 of the tip 11a.

  FIG. 4 is a timing chart of the drive pulse signal, the image signal, and the sample hold signal input to the CCD 22 with respect to the clock signal CK. Specifically, FIG. 4 shows the drive pulse signal (RG, H1, H2) input to the CCD 22, the output of the CCD 22 (CCD-OUT), and the ideal sample hold signal (SH1_0) with respect to the clock signal CK. , SH2_0), an image signal (AFE-IN) actually input to the AFE unit 42, and appropriate sample hold signals (SH1, SH2).

  The drive pulse signal supplied to the CCD 22 includes three types of reset gate pulse signals (hereinafter referred to as RG signals) and horizontal transfer pulses H and H2, and is generated from the basic clock CK.

In FIG. 4, the waveform of the drive pulse signal (RG, H1, H2) input to the CCD 22 is an output waveform immediately after the output of the waveform shaping circuit 23.
By supplying three types of drive pulse signals (RG, H1, H2) to the CCD 22, a waveform such as an output (CCD-OUT) is output from the CCD 22. The output (CCD-OUT) has an ideal waveform with very little waveform distortion and delay. In FIG. 4, ideal sample hold signals (SH1_0, SH2_0) are output at appropriate timings in the feedthrough period Z1 and the signal charge period Z2 of the output of the image signal (CCD-OUT) at the output terminal of the CCD 22. Yes. The waveform of the output (CCD-OUT) corresponds to the pulse waveform of the RG signal, and the signal charge period Z2 that reacts to light is determined by the timing of these three pulse signals (RG, H1, H2).

  In the case of the endoscope apparatus, the drive pulse signal (RG, H1, H2) generated by the TG section 55 of the main body section 12 is sent to the CCD 22 of the distal end section 11a, and an image signal is output from the CCD 22, and the main body section. Return to 11. The tip portion 11a and the main body portion 12 are connected by a cable for transmitting an electrical signal.

  Since the waveform of the image signal (AFE-IN) input to the AFE 42 through the thin signal line cable in the elongated insertion portion 11 is dull, both the feedthrough period Z1 and the signal charge period Z2 are shortened. Further, since the signal line propagates through a thin and long signal line, an electrical delay of several tens of nsec or more occurs between the output (CCD-OUT) and the image signal (AFE-IN), and the image signal from the CCD 22 depends on the ambient temperature of the CCD 22. Therefore, the time required for returning to the CDS unit 51 varies by several nsec.

  For example, when the CCD 22 is 250,000 pixels, the one-pixel period Z0 is about 100 nsec (nanoseconds), and the feed-through period Z1 sampled and held by the CDS unit 51 and the signal charge period Z2 have a stable period of about 5 to 10 nsec. Even if a time lag of several nsec (that is, a phase lag) occurs, no major problem occurs. However, for example, in the case of one million pixels, the one pixel period Z0 is only about 25 nsec, and the feedthrough period Z1 sampled and held by the CDS unit 51 and the stable period of the signal charge period Z2 can be secured only 2 to 4 nsec.

Therefore, if the image signal of the CCD 22 is delayed by several nsec, the CDS unit 51 cannot properly perform sample and hold processing, and a normal video signal cannot be obtained in the CDS unit 51. In the worst case, an endoscopic image is displayed. become unable. In the case of the endoscope apparatus 1, the timing of the sample hold signal (SH1, SH2) is ideal with respect to the output immediately after the output of the CCD 22 (CCD-OUT) as shown in FIG. 4 depending on the temperature of the distal end portion 11a. This is different from the timing of the sample hold signals (SH1_0, SH2_0).
Therefore, in the present embodiment, the timing or pulse width of the sample hold signal (SH1, SH2) is corrected according to the temperature of the tip portion 11a.

  The correction value table TBL1 in FIG. 3 includes correction values for the sample hold signal (SH1, SH2) and the timing (ie, phase) of the conversion timing signal ADCK to the A / D unit 53. Here, the temperature T1 of the tip 11a is -10 ° C to 19 ° C, 20 ° C to 39 ° C, 40 ° C to 59 ° C, 60 ° C to 79 ° C, 80 ° C to 99 ° C, 100 ° C to 110 ° C. It is classified into one range. Therefore, the correction value data of six patterns are stored in the correction value table TBL1 here. For example, the correction values of the timing pulse signals SH1, SH2, and ADCK differ depending on the change in the temperature T1 of the tip portion 11a. Each correction value is a correction value for outputting each timing pulse signal (SH1, SH2, ADCK) at an appropriate timing in the feedthrough period Z1 or the like according to the temperature T1 of the tip end portion 11a.

In FIG. 3, when the temperature T1 of the tip end portion 11a is increased, the waveform of the image signal input to the AFE unit 42 is delayed, so that each correction value is increased. As shown in FIG. 4, when the temperature T1 of the tip end portion 11a increases, the feedthrough period Z1 and the signal charge period Z2 in the image signal are delayed, and the timing of the sample hold signals (SH1, SH2) is indicated by the dotted line. Shifted to A1. In FIG. 4, the conversion timing signal ADCK to the A / D unit 53 is not shown. In FIG. 4, the direction indicated by + indicates the direction in which the waveform of the image signal is delayed, and the direction indicated by-indicates the direction in which the waveform is accelerated.
Therefore, the CPU 44 adjusts the timing of the sample hold signal (SH1, SH2) and the conversion timing signal ADCK to the A / D unit 53 based on the temperature T1 of the tip end portion 11a.

  FIG. 5 is a flowchart illustrating an example of a flow of timing signal correction processing by the CPU 44. The CPU 44 inputs the temperature T1 of the tip 11a, that is, the temperature information of the temperature sensor 24 (S1). Then, referring to the data of the correction value table TBL1 in the EPROM 45 (S2), each correction value of the sample hold signal (SH1, SH2) corresponding to the input temperature information and the conversion timing signal ADCK to the A / D unit 53 Is read (S3).

  Then, the CPU 44 outputs the read correction values to the TG unit 55 (S4). The TG unit 55 outputs each timing signal (SH1, SH2, ADCK) corrected based on each input correction value. Specifically, the CPU 44 adjusts the timing of each timing signal (SH1, SH2, ADCK) by changing the phase of each timing signal (SH1, SH2, ADCK). As a result, even if the temperature T1 of the tip 11a changes, various timing signals are supplied to the CDS unit 51 and the A / D unit 53 at an appropriate timing corresponding to the temperature T1.

The CPU 44 determines whether or not a predetermined time, for example, 5 seconds has elapsed (S5). If the predetermined time has not elapsed (S5; NO), the CPU 44 does nothing and when the predetermined time has elapsed ( S5; YES), the process returns to S1, and the above-described process is repeated.
Accordingly, since the timing signals (SH1, SH2, ADCK) are supplied to the CCD 22 at appropriate timings corresponding to the temperature T1, the correlated double sampling process and the A / D conversion process are appropriately performed.

FIG. 3 shows correction values for correcting the timing of each timing signal (SH1, SH2, ADCK), but the same applies to correction values for correcting the pulse width of each timing signal (SH1, SH2, ADCK). An effect can be obtained. That is, the CPU 44 and the TG 55 which are timing adjustment units change the timing of each timing signal (SH1, SH2, ADCK), the sample hold signal (SH1, SH2), and the pulse width of the conversion timing signal ADCK to the A / D unit 53. Adjust by changing.
For example, in FIG. 4, the pulse width is changed so that the timing of the rising edges of the pulse widths W1 and W2 of the sample and hold signals (SH1 and SH2) is increased in the direction indicated by the dotted arrow Aa.

  Furthermore, both the timing (ie, phase) and pulse width of each timing signal (SH1, SH2, ADCK) are corrected simultaneously so that each timing signal (SH1, SH2, ADCK) is supplied at an appropriate timing. It may be. Each timing signal (SH1, SH2, ADCK) is supplied to the CCD 22 at an appropriate timing even if both the timing and pulse width of each timing signal (SH1, SH2, ADCK) are corrected corresponding to the temperature T1. Therefore, the correlated double sampling process and the A / D conversion process are appropriately performed.

  The above example is an example of correcting the timing or pulse width of the sample hold signal (SH1, SH2) and the conversion timing signal ADCK to the A / D unit 53, but the drive pulse signal (RG, H1, H2). ) Timing (ie, phase) may be corrected.

  FIG. 6 is a diagram illustrating an example of a correction value table of timings of the drive pulse signals (RG, H1, H2) stored in the EPROM 45. The correction value table TBL2 stores correction values of the drive pulse signals (RG, H1, H2) supplied to the CCD 22.

  In FIG. 6, when the temperature T1 of the tip portion 11a is increased, the waveform of the image signal input to the AFE unit 42 is delayed, so that each correction value is increased. As shown in FIG. 4, when the temperature T1 of the tip end portion 11a is increased, the feedthrough period T1 and the signal charge period T2 in the image signal are delayed, so that the timing of the drive pulse signals (RG, H1, H2) is indicated by a dotted line. The direction is shifted in the direction A2.

The CPU 44 also uses the correction value table TBL2 shown in FIG. 6 to output the correction values of the drive pulse signals (RG, H1, H2) to the TG 55, so that the sample hold is performed in the feedthrough period Z1 and the signal charge period Z2. Since the timings of the signals (SH1, SH2) can be synchronized, the correlated double sampling process is appropriately performed in the CDS unit 51. The processing of the CPU 44 in this case is the same as the processing of FIG. 5, the referenced table is the correction value table TBL2 of the timing of the driving pulse signals (RG, H1, H2), and the CPU 44 outputs the driving The only difference is the correction value of the timing of the pulse signals (RG, H1, H2).
Furthermore, the timing (ie, phase) of the drive pulse signal (RG, H1, H2) is combined with the timing (ie, phase) or pulse width (or both phase and pulse width) of the sample hold signal (SH1, SH2). You may make it adjust. That is, the timings of both the sample hold signal (SH1, SH2) and the drive pulse signal (RG, H1, H2) may be adjusted so that the correlated double sampling process is appropriately performed.

As described above, according to the electronic endoscope apparatus according to the above-described embodiment, in the electronic endoscope apparatus having an elongated insertion portion, the distal end portion of the insertion portion of the endoscope is used in various temperature ranges. Even in this case, the correlated double sampling process is appropriately performed.
(Modification 1)
In the endoscope apparatus 1 described above, the CPU 44 supplies correction values to the TG 55 with reference to the correction value table in the EPROM 45 corresponding to the temperature T1 of the distal end portion 11a. You may make it read.

  As shown by a dotted line in FIG. 1, a RAM 71 may be provided, and a correction value table (TBL1 or TBL2) may be transferred to the RAM 71 from the EPROM 45 so that the TG 55 can read it by referring to the correction value table.

In this case, the CPU 44 notifies the TG 55 which correction value data of the correction value table is used according to the temperature of the tip end portion 11a, so that the TG 55 reads the correction value and outputs a timing signal (drive pulse signal ( RG, H1, H2) and sample hold signals (SH1, SH2)) are corrected for timing or pulse width and output.
Further, in the example of FIG. 1, TG 55 is taken into the FPGA 43, but TG 55 may be taken into the AFE unit 42 instead. This is because in recent years, the CCD drive frequency has increased as the number of pixels has increased, and in many cases, the TG 55 is incorporated into the AFE unit 43 in order to perform correlated double sampling processing more stably. Therefore, the present embodiment can also be applied to such a form.

  FIG. 7 is a flowchart showing an example of the flow of timing signal correction processing of the CPU 44 according to this modification. Here, the example of the correction value table TBL1 will be described, but the same applies to the correction value table TBL2.

  The CPU 44 first reads the data of the correction value table TBL1 from the EPROM 45 and writes it in the RAM 71 (S11). The CPU 44 inputs the temperature T1 of the tip 11a, that is, the temperature information of the temperature sensor 24 (S12). Then, referring to the data of the correction value table TBL1 in the EPROM 45 (S2), each correction value of the sample hold signal (SH1, SH2) corresponding to the input temperature information and the conversion timing signal ADCK to the A / D unit 53 A correction value number corresponding to is determined (S13). For example, in FIG. 3, if the temperature T1 of the front end portion 11a is 45 ° C., the CPU 44 determines that the correction value number is “3”.

  Then, the CPU 44 outputs the determined correction value number to the TG unit 55 (S14). The TG unit 55 reads each correction value corresponding to the input correction value number from the RAM 71, and outputs each timing signal (SH1, SH2, ADCK) at the corrected timing. As a result, even if the temperature T1 of the tip 11a changes, various timing signals are supplied to the CDS unit 51 and the A / D unit 53 at an appropriate timing corresponding to the temperature T1.

The CPU 44 determines whether or not a predetermined time, for example, 5 seconds has elapsed (S15). If the predetermined time has not elapsed (S15; NO), the CPU 44 does nothing and when the predetermined time has elapsed ( S15; YES), the process returns to S1, and the above-described process is repeated.
Accordingly, also in the present modification, the sampled hold signals (SH1, SH2) are supplied at an appropriate timing corresponding to the temperature T1 of the tip portion 11a, so that an appropriate correlated double sampling process is performed.
(Modification 2)
A modification of the waveform shaping circuit 23 will be described.
In the endoscope apparatus 1 described above, the CCD 22 of the distal end portion 11a is driven through a signal line that passes through the elongated insertion portion 11, and the waveform of the drive pulse signal (RG, H1, H2) input to the CCD 22 is When reaching the section 11a, distortion occurs due to dullness in the RLC component of the signal line or crosstalk between various signals. These distortions and the like tend to increase as the insertion length becomes longer. Therefore, in particular, the horizontal transfer pulses H1 and H2 are corrected to waveforms with sharp edges using waveform shaping means, and the CCD 22 is driven. This is because the horizontal transfer efficiency of the CCD 22 decreases and the image quality deteriorates unless the edges of the waveforms of the horizontal transfer pulses H1 and H2 are sharp.

  As described above, in recent years, one pixel period Z0 has been shortened due to an increase in the number of pixels of the image sensor. For example, one pixel period is about 100 nsec (nanosecond) in 250,000 pixels, whereas one pixel period is one pixel. The period becomes about 25 nsec, which is about 1/4. In this case, if the edge of the pulse signal of the RG signal is not sharp, the image quality is deteriorated, so that waveform shaping is necessary. Therefore, not only H1 but also RG is needed for waveform shaping.

  Waveform rounding and distortion vary slightly depending on the signal line specifications, length, and insertion section status, so even if the waveform shaping circuit can shape the waveform, this time it will be subtle between the horizontal transfer pulses H1 and H2. A phase difference occurs. Since the horizontal transfer pulses H1 and H2 are in an opposite phase relationship, the charge of the image sensor can be efficiently transferred horizontally. For some reason, if a slight phase difference occurs between the horizontal transfer pulses H1 and H2, the cross-switching characteristics of the horizontal transfer pulses H1 and H2 will deteriorate and the image sensor will not be able to transfer charges efficiently. Bring Therefore, the horizontal transfer pulses H1 and H2 are completely in reverse phase, and it is important to prevent the phase difference from occurring as much as possible.

  Further, since the frequency of the drive pulse signal (RG, H1, H2) increases as the number of pixels of the image sensor increases, transmission loss and distortion of a long signal line passing through the insertion unit 11 become larger. For this reason, the signal line needs to be thicker as the image sensor having a larger number of pixels is used, which in turn has become a factor that makes the design difficult, for example, it does not fit in the diameter of the insertion portion.

  Therefore, paying attention to the point that the horizontal transfer pulses H1 and H2 are out of phase, in this modification, only one of the horizontal transfer pulses H1 or H2 passing through the insertion section 11 is transmitted, and the other phase is inverted by the waveform shaping circuit. The horizontal transfer pulse H2 or H1 is generated.

  FIG. 8 is a circuit diagram of a circuit 23b for supplying drive pulse signals (RG, H1, H2) according to this modification. Each drive pulse from the main body 12 is an RG signal and a horizontal transfer pulse H1, and the horizontal transfer pulse H2 inputs the horizontal transfer pulse H1 and outputs an output of a comparator CM that outputs a comparison result with a predetermined threshold value. The signal is generated by being input to an amplifier AMPa that amplifies by phase inversion.

Therefore, according to this modification, there is no phase difference between the horizontal transfer pulses H1 and H2, the cross-switching characteristics of the horizontal transfer pulses H1 and H2 are improved, and the charge transfer efficiency of the image sensor can be increased. .
Further, in the case of FIGS. 2 and 8, the waveform shaping is performed with the potential on one side of the comparator CM of the waveform shaping circuit 23 being fixed to DC, but this DC voltage is not fixed, and from the main body 12 via the signal line. A DC voltage may be sent to shape the waveform. When this DC voltage changes, the waveform shaping operating point changes, so the pulse width of the output waveform of the comparator CM can be changed. For example, an analog voltage value is obtained through a D / A converter (not shown) so that the digital output value from the CPU 57 is linked to the correction value table TBL2, and this analog voltage is used as the DC voltage of the waveform shaping circuit 23 as the DC voltage. You may send it. That is, the phase of the drive pulse signal (RG, H1, H2) may be adjusted by changing the operating point of the comparator CM in the waveform shaping circuit 23.
By the way, when the timing adjustment of the sample hold signal or the drive pulse signal is performed, depending on the AFE unit 42 including the CDS unit 51, noise may be superimposed on the output image of the AFE unit 42 during the timing adjustment. This image noise degrades the image quality. In order to avoid this, the timing adjustment of the drive pulse signal can be effectively eliminated by adjusting it outside the CCD 22 image output period. Specifically, the timing adjustment of the sample hold signal (SH1, SH2) or the drive pulse signal (RG, H1, H2) is performed during the blanking period of the video.
Further, performing the timing adjustment means that the sample hold operation in the CDS unit 51 slightly changes, and not only the image noise but also the brightness slightly changes. If the timing is frequently adjusted, the brightness is very small but frequently changes, which may cause the image to flicker and the stability of the image to be lost. In order to avoid this, it is only necessary that the control target numbers in the correction value tables TBL1 and TBL2 do not change frequently. Specifically, for example, there is a partition between 19 ° C and 20 ° C. However, a dead zone is provided for each partition, or a hysteresis characteristic is given when the temperature changes and this partition is crossed. The number is controlled so as not to change.
(Second Embodiment)
In the first embodiment, the timing and / or pulse width of various timing signals are corrected based on the temperature of the distal end portion 11a of the insertion portion 11. In the present embodiment, the distal end portion 11a In consideration of not only the temperature T1 but also the temperature T2 of the main body 12, the timing and / or pulse width of various timing signals are corrected.

  The temperature of the main body 12 may also change greatly depending on the user's usage environment. For example, the temperature environment in which the endoscope apparatus is used is wide, from an extremely cold environment of 20 ° C. below freezing point where humans can perform inspection to an extremely hot environment of 45 ° C.

  Therefore, in the present embodiment, the timing and / or pulse width of various timing signals are corrected using a correction value table that takes into account both the temperature T1 of the distal end portion 11a and the temperature T2 of the main body portion 12.

  FIG. 9 is a configuration diagram showing the configuration of the endoscope apparatus according to the present embodiment. In FIG. 9, the same components as those of FIG. 1 are denoted by the same reference numerals and description thereof is omitted, and different configurations will be described.

As shown in FIG. 9, the CCU 31 of the endoscope apparatus 1A is provided with a temperature sensor 46 for detecting the temperature of the main body 12. Further, the CPU 44 includes an A / D unit 57. The A / D unit 57 converts the analog signal from the temperature sensor 46 of the main body 12 into a digital signal, and supplies the temperature data of the main body 12 to the CPU 44. The CPU 44 selectively receives voltage signals from the temperature sensors 24 and 46, and calculates respective temperature information from the digital data of the voltage signals.
The temperature sensor 46 is, for example, a thermistor. Since various circuits of the CCU 31 are configured by a semiconductor device, the temperature sensor 46 can detect the temperature of the main body 12 by being provided in the vicinity of the semiconductor device.

  Further, instead of the temperature sensor 46 described above, a temperature detection unit that detects the temperature from the DC component of the impedance conversion element may be used by using the technique disclosed in Japanese Patent Application Laid-Open No. 2007-125111.

  The EPROM 45 stores a table having temperature information of the two temperature sensors 24 and 46 and phase adjustment times or pulse width adjustment information of various pulses generated by the TG unit 55. The CPU 44 refers to the data in the EPROM 45, refers to the table from the two temperature information, reads out the phase adjustment value or the pulse width adjustment value from the EPROM 45, and outputs it to the TG unit 55.

  In addition, the CPU 44 displays the temperature information of the temperature sensors 24 and 46 as temperature information on the screen of the LCD 13, or displays the brightness, color density, random noise, etc. of the video displayed according to the temperature information. In order to reduce the temperature information, the temperature information can be transmitted to the video signal processing unit 54 in the FPGA 43 and the image processing LSI 58 at a later stage by communication.

  FIG. 10 is a diagram illustrating an example of a CDS timing correction value table stored in the EPROM 45. The unit of the correction value is, for example, nsec (nanosecond). The correction value table TBL3 corresponds to each correction of each timing signal (SH1, SH2, ADCK) to the CDS unit 51 and the A / D unit 53 corresponding to the combination of the temperature T1 of the tip 11a and the temperature T2 of the main body 12. Stores a value.

  Here, the temperature T1 of the tip 11a is -10 ° C to 19 ° C, 20 ° C to 39 ° C, 40 ° C to 59 ° C, 60 ° C to 79 ° C, 80 ° C to 99 ° C, 100 ° C to 110 ° C. The temperature T2 of the main body 12 is classified into three ranges of −10 ° C. to 19 ° C., 20 ° C. to 39 ° C., and 40 ° C. to 40 ° C. Then, the correction value data of the number of combinations of these classifications, here 18 patterns, is stored in the correction value table TBL3. Each correction value is output so that each timing signal (SH1, SH2, ADCK) is output at an appropriate timing in the feedthrough period T1 or the like according to the temperature D1 of the distal end portion 11a and the temperature D2 of the main body portion 12. Is the correction value.

For example, when the temperature T2 of the main body 12 becomes higher than the temperature T1 of the tip 11a, the waveform of the image signal input to the AFE unit 42 is delayed, so that each correction value is small.
The processing of the CPU 44 in the present embodiment is the same as the processing shown in FIGS. 5 and 7 of the first embodiment. 5 and 7, in the temperature sensor temperature information input process (S1, S12), the temperature information of the two temperature sensors 24 and 46 is input, and the CPU 44 sets the correction value corresponding to the combination of the temperatures to the EPROM 45. And output to TG55.

  Therefore, the CPU 44 which is a timing adjustment unit, based on the temperature T1 of the tip end part 11a and the temperature T2 of the main body part 12, and the sample hold signal (SH1, SH2) generated by the TG part 55 and the A / D part 53 Adjust the timing of the conversion timing signal ADCK.

  In the present embodiment, each timing signal is corrected using a correction value for correcting the pulse width of each timing signal (SH1, SH2, ADCK) instead of the phase of each timing signal (SH1, SH2, ADCK). The timing of (SH1, SH2, ADCK) may be adjusted.

  Furthermore, also in this embodiment, the correction value that corrects the timing (ie, phase) of each timing signal (SH1, SH2, ADCK) and the pulse width of each timing signal (SH1, SH2, ADCK) is also used. Thus, the timing of each timing signal (SH1, SH2, ADCK) may be adjusted.

  Further, the above-described example is an example in which the timing pulse signals SH1, SH2, and ADCK are corrected. However, as in the first embodiment, the timing (ie, phase) of the drive pulse signals (RG, H1, H2). ) May be corrected.

  FIG. 11 is a diagram illustrating an example of a correction value table of timings of the drive pulse signals (RG, H1, H2) stored in the EPROM 45. The correction value table TBL4 stores correction values of the drive pulse signals (RG, H1, H2) supplied to the CCD 22.

  Even when the correction value table of FIG. 11 is used, the endoscope apparatus 1A can perform appropriate correlated double sampling processing by the same processing as the processing described in the first embodiment.

  Further, in this embodiment, the timing (ie, phase) or pulse width (or both phase and pulse width) of the sample hold signal (SH1, SH2) and the timing of the drive pulse signal (RG, H1, H2) ( That is, the phase may also be adjusted. That is, the timings of both the sample hold signal (SH1, SH2) and the drive pulse signal (RG, H1, H2) may be adjusted so that the correlated double sampling process is appropriately performed.

  Therefore, according to the present embodiment, even when the distal end portion 11a and the main body portion 12 are separated from each other and are used under different temperature environments, the correlated double sampling processing is appropriately performed in the CDS portion 51. It is possible to provide an endoscope apparatus.

  Furthermore, the contents of Modification 1 and Modification 2 described in the first embodiment can also be applied to this embodiment.

  According to each embodiment and each modification described above, in an electronic endoscope apparatus having an elongated insertion portion, even when the distal end portion of the insertion portion of the endoscope is used in various temperature ranges, An electronic endoscope apparatus that can appropriately perform correlated double sampling processing can be realized.

  The present invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A endoscope apparatus, 11 Insertion part, 11a Tip part, 12 Main body part, 13 LCD, 14 Recording medium, 21 LED, 22 CCD, 23 Waveform shaping circuit, 24, 46 Temperature sensor, 31 Camera control unit, 32 Recording / playback unit, 33 LED drive circuit, 34 LCD driver circuit, 35 operation unit, 41 preamplifier, 42 analog front end unit, 43 FPGA, 44 CPU, 45 EPROM, 51 CDS unit, 52 AGC unit, 53, 56, 57 A / D section, 54 video processing section, 55 timing generator, 58 image processing LSI, 59 connector

Claims (11)

An image sensor provided at the distal end of the endoscope insertion portion;
A first temperature detector for detecting a first temperature of the tip;
A correlated double sampling unit provided in a main body unit to which a proximal end of the endoscope insertion unit is connected, for extracting a signal component from an image signal output from the imaging device;
A cable for transmitting an electrical signal between the tip and the main body,
A timing generator for generating a sample hold signal for operating the correlated double sampling unit and a driving pulse signal for driving the imaging device, provided in the main body unit;
A timing adjustment unit that adjusts the timing of the sample hold signal or the drive pulse signal generated by the timing generation unit based on the first temperature detected by the first temperature detection unit;
An electronic endoscope apparatus comprising: A second temperature detector for detecting a second temperature of the main body;
The timing adjustment unit adjusts the timing of the sample hold signal or the drive pulse signal generated by the timing generation unit based on the first and second temperatures. Electronic endoscope device.   The electronic endoscope apparatus according to claim 1, wherein the timing adjustment unit adjusts the timing of the sample and hold signal by changing a phase or a pulse width of the sample and hold signal.   The electronic endoscope apparatus according to claim 1, wherein the timing adjustment unit adjusts the timing of the drive pulse signal by changing a phase of the drive pulse signal.   The timing adjustment unit adjusts the timing of the sample and hold signal by changing the phase or pulse width of the sample and hold signal, and changes the timing of the driving pulse signal and the phase of the driving pulse signal. The electronic endoscope apparatus according to claim 1, wherein the electronic endoscope apparatus is adjusted by the adjustment. An analog-digital conversion unit that converts the image signal of the analog signal output from the correlated double sampling unit into a digital signal;
The electronic endoscope apparatus according to claim 1, wherein the timing adjustment unit also adjusts a timing of a conversion timing signal input to the analog-digital conversion unit.   The timing adjustment unit refers to a table storing a correction value for correcting the timing, and uses the correction value corresponding to the first temperature read from the table, and uses the sample hold signal or the drive The electronic endoscope apparatus according to claim 1, wherein the timing of the pulse signal is adjusted.   The timing adjustment unit refers to a table storing a correction value for correcting the timing, and uses a correction value corresponding to a combination of the first temperature and the second temperature read from the table. The electronic endoscope apparatus according to claim 2, wherein the timing of the sample hold signal or the drive pulse signal is adjusted.   The electronic endoscope apparatus according to claim 1, further comprising a temperature display unit that displays the first temperature.   The electronic endoscope according to claim 1, further comprising a waveform shaping circuit that is provided at the distal end portion and shapes a waveform of the drive pulse signal supplied to the imaging device. apparatus.   11. The electronic endoscope apparatus according to claim 1, wherein timing adjustment of the sample hold signal or the drive pulse signal is performed during a blanking period of video.

Images