JP2008200344A - Electronic endoscope and endoscope processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the number of signal lines for transmitting image signals of an electronic endoscope converted to digital data. <P>SOLUTION: The electronic endoscope has an imaging unit 30 at the tip of the inserting tube and the imaging unit 30 has a CMOS image sensor 31, an A/D converter 33 and an error correction modulation part 35 and a QPSK modulation part 36. The CMOS image sensor 31 generates the image signals, the A/D converter 33 converts the image signals to the image data and the error correction modulation part 35 adds an error correction code corresponding to the image data to the image data. The QPSK modulation part 36 accomplishes a 4 phase shift modulation of the image data with the error correction code added. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic endoscope that transmits an image signal generated by photographing a subject image as digital data from the distal end of an insertion tube, and an endoscope processor connected to the electronic endoscope.

  In recent years, it has been proposed to use a CMOS image sensor for an electronic endoscope. Since the CMOS image sensor is manufactured using a CMOS LSI manufacturing process, it is easy to form an image pickup unit by mounting a timing generator (TG) and an A / D converter together with the image sensor on the same substrate.

  This imaging unit is provided at the distal end portion of the insertion tube of the electronic endoscope. The image signal generated by the image sensor is converted into digital data in the image capturing unit. Digital data is transmitted from the distal end of the insertion tube to the endoscope processor via the endoscope body. Thus, by converting into digital data at the distal end of the insertion tube, it is possible to reduce image quality degradation due to noise.

  However, in order to transmit digital data, it has been a problem that it is necessary to increase the number of signal lines compared to the transmission of analog signals. For example, the insertion tube of an electronic endoscope is required to be reduced in diameter, but the increase in signal line makes it increasingly difficult to reduce the diameter. In addition, the manufacturing process is complicated due to the increase in signal lines.

  Therefore, it has been proposed to reduce signal lines by converting RAW DATA generated by the imaging unit, that is, RGB signals into YCrCb signals, and transmitting the color difference signals CrCb in a time-division manner.

However, the method of Patent Document 1 has a problem in that the image quality deteriorates when demodulating into an RGB signal because the information amount of the color difference signal is reduced. In addition, further signal line reduction has been demanded.
JP-A-5-316513

  Accordingly, an object of the present invention is to prevent deterioration in image quality while reducing the number of signal lines of an electronic endoscope that transmits an image signal converted into digital data at a distal end portion of an insertion tube.

  An electronic endoscope according to the present invention is an electronic endoscope in which an insertion tube is connected to a main body. The electronic endoscope is provided at a distal end portion of the insertion tube, receives an optical image of a subject, and analogizes an image signal corresponding to the optical image. An image sensor to be generated as a signal, an A / D converter for converting an image signal into digital image data provided at the distal end of the insertion tube, and 2 ^ n for the image data provided at the distal end of the insertion tube And a PSK modulator that performs phase transition modulation of a phase (n is an integer of 2 or more).

  It is preferable to provide a PSK demodulator that is provided in the main body and demodulates image data that has been phase-shift modulated by the PSK modulator.

  It is preferable that an error correction modulation unit is provided at the distal end of the insertion tube and adds an error correction code to image data, and the PSK modulation unit performs phase transition modulation on the image data to which the correction code is added.

  The correction modulation unit preferably adds an error correction code to the image data according to a block code method.

  Further, it is preferable to include an error correction demodulator that is provided in the main body and corrects an error of the image data to which the correction code is added based on the correction code.

  The first endoscope processor of the present invention is an electronic endoscope in which an insertion tube is connected to a main body, and is provided at the distal end portion of the insertion tube and receives an optical image of a subject and corresponds to the optical image. An image sensor that generates a signal as an analog signal, an A / D converter that converts an image signal into digital image data provided at the distal end of the insertion tube, and an image data that is provided at the distal end of the insertion tube An endoscope processor for receiving image data from an electronic endoscope comprising a 2 ^ n phase (n is an integer equal to or greater than 2) phase shift modulation, and phase shift modulated by the PSK modulator And a PSK demodulator for demodulating the received image data.

  The second endoscope processor of the present invention is an electronic endoscope in which an insertion tube is connected to a main body, and is provided at the distal end portion of the insertion tube and receives an optical image of a subject and corresponds to the optical image. An image sensor that generates a signal as an analog signal, an A / D converter that converts an image signal into digital image data provided at the distal end of the insertion tube, and an image data that is provided at the distal end of the insertion tube The PSK modulation unit includes a PSK modulation unit that performs phase transition modulation of 2 ^ n phase (n is an integer of 2 or more) and an error correction modulation unit that is provided at the distal end of the insertion tube and adds an error correction code to image data. An endoscope processor for receiving image data from an electronic endoscope that performs phase transition modulation on image data to which a correction code is added, and which is based on the correction code for errors in the obtained image data to which the correction code is added Correct It is characterized in that it comprises an error correction demodulator.

  According to the present invention, in an electronic endoscope, it is possible to prevent an increase in signal lines when converting an image signal generated while preventing deterioration in image quality into digital data.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram schematically showing an internal configuration of an endoscope system having an electronic endoscope and an endoscope processor to which an embodiment of the present invention is applied.

  The endoscope system 10 includes an electronic endoscope 20, an endoscope processor 40, and a monitor 11. The electronic endoscope 20 is connected to the endoscope processor 40 via the connector 21. The monitor 11 is also connected to the endoscope processor 40 via a connector (not shown).

  Inside the electronic endoscope 20, a light guide 24 is provided so as to extend from the connector 21 through the main body 23 to the distal end of the insertion tube 22. Light supplied from a light source unit 41 provided in the endoscope processor 40 is transmitted to the distal end of the insertion tube 22 by the light guide 24.

  Light emitted from the emission end of the light guide 24 is applied to the vicinity of the distal end of the insertion tube 22 through the light distribution lens 25. The subject irradiated with the illumination light is imaged by the imaging unit 30 provided at the distal end of the insertion tube 22.

  The captured image is transmitted to the endoscope processor 40 as an image signal. The image signal transmitted to the endoscope processor 40 is subjected to predetermined processing and then output to the monitor 11 where a subject image is displayed.

  Next, the configuration of the imaging unit 30 will be described with reference to FIG. FIG. 2 is a block diagram schematically showing the circuit configuration of the imaging unit 30. As shown in FIG. The imaging unit 30 is formed on the same substrate by a CMOS imaging element 31, a timing generator (TG) 32, an A / D converter 33, an RGB conversion unit 34, an error correction modulation unit 35, and a QPSK modulation unit 36. The imaging unit 30 is manufactured using a CMOS LSI manufacturing process.

  The CMOS image sensor 31 and the objective lens 26 (see FIG. 1) are optically connected. The reflected light of the subject irradiated with the illumination light forms an image on the light receiving surface of the CMOS image sensor 31 via the objective lens 26. The CMOS image sensor 31 generates an image signal corresponding to the optical image of the subject that receives light.

  The TG 32 causes each part of the CMOS image sensor 31 to execute a predetermined operation at a predetermined timing, thereby generating an image signal. The driving of the CMOS image sensor 31 by the TG 32 is controlled by an image sensor driver 42 provided in the endoscope processor 40.

  An effective pixel area AA and a blanking pixel area BA are provided on the light receiving surface of the CMOS image sensor 31. A plurality of pixels (not shown) are arranged in a matrix in the effective pixel area AA and the blanking pixel area BA.

  Each pixel arranged in the effective pixel area AA is covered with an RGB color filter (not shown) arranged according to the Bayer method. The light receiving surface of each pixel arranged in the blanking pixel area BA is shielded from light.

  In each pixel, a pixel signal corresponding to the amount of light received through the color filter is generated. That is, an R pixel signal is generated from a pixel covered with an R color filter, a G pixel signal is generated from a pixel covered with a G color filter, and a B pixel signal is generated from a pixel covered with a B color filter. A blanking pixel signal is generated from the light-shielded pixel. One frame of the image signal is composed of a plurality of pixel signals. Pixel signals are output from the CMOS image sensor 31 in order.

  The generation and output of the pixel signal is performed for each row. As shown in FIG. 3, during the period when the horizontal synchronization signal is HIGH, pixel signals from the first column pixel to the last column (α column) in the effective pixel area AA of the first row are sequentially generated, Is output. During the period when the horizontal synchronization signal is LOW, a blanking pixel signal is generated from the pixels in the same blanking area BA in the first row and output.

  After a predetermined period after the pixel signals are output from the pixels in the effective pixel area AA and blanking pixel area BA in the first row, the pixel signals from the pixels arranged in the next second row are output. Thereafter, pixel signals from the pixels in the third row, etc. are output. An image signal is formed by the pixel signals generated by the pixels arranged in the effective pixel area AA and the blanking pixel area BA output in this way.

  The image signal generated by the CMOS image sensor 31 is sent to the A / D converter 33. The image signal that is an analog signal is converted by the A / D converter 33 into image data that is 8-bit digital data. As described above, the image signal is formed by a plurality of pixel signals, and each pixel signal is converted into pixel data which is 8-bit digital data by the A / D converter 33 (FIG. 3 pixel data (A / D converter output))).

  Pixel data is sent to the RGB converter 34. In the RGB converter 34, the image data is separated into RGB pixel data. The R pixel data, G pixel data, and B pixel data correspond to an R pixel signal, a G pixel signal, and a B pixel signal, respectively.

  Further, the RGB conversion unit 34 performs color interpolation processing, and R pixel data, G pixel data, and B pixel data corresponding to each pixel are interpolated.

  Each pixel data is sent to the error correction modulation unit 35. In the error correction modulation unit 35, first to eighth information blocks are formed. As described above, there are R pixel data, G pixel data, and B pixel data corresponding to each pixel, and the first to eighth information blocks are formed separately for RGB. In the following description, although distinction between RGB is not described, data processing corresponding to each color is performed until data processing in the image processing unit 46 (see FIG. 1).

  The first information block is formed by arranging the 1-bit codes of pixel data arranged in the same row (see error correction pixel data in FIG. 3). Note that the order in which the symbols are arranged is the same as the order in which the pixels from the first column in the effective pixel area AA to the pixels in the last column in the blanking pixel area BA are arranged. Similarly, the second to eighth information blocks are formed by arranging the second to eighth bit codes of the pixel data arranged in the same row.

  Further, the error correction modulation unit 35 generates error correction codes corresponding to the first to eighth information blocks. Error correction pixel data is generated by adding the generated error correction code to each information block. The error correction code is a block code such as a BCH code or a Reed-Solomon code.

  The generated error correction pixel data is sent to the QPSK modulator 36. In the QPSK modulation section 36, the error correction pixel data is subjected to four-phase phase transition modulation (QPSK), and is modulated into phase-modulated pixel data which is 4-bit pixel data.

  For example, QPSK is performed with a combination of error correction pixel data of 1 and 2 bits, error correction pixel data of 3 and 4 bits, error correction pixel data of 5 and 6 bits, and error correction pixel data of 7 and 8 bits (see FIG. (See 3-phase modulated pixel data). Phase-modulated pixel data corresponding to one frame of image data is sent to the endoscope processor 40 as the aforementioned image signal.

  Next, the internal configuration of the endoscope processor 40 will be described. As described above, the endoscope processor 40 is provided with the light source unit 41 and the image sensor driver 42 (see FIG. 1). The endoscope processor 40 is provided with a system controller 43, a QPSK demodulator 44, an error correction demodulator 45, and an image processor 46.

  The system controller 43 controls the operation of the entire endoscope processor 40. For example, the image pickup unit 30 is driven by the image pickup device driver 42 being controlled by the system controller 43.

  The system controller 43 also controls demodulation processing and signal processing executed by a QPSK demodulator 44, an error correction demodulator 45, and an image processor 46 described later.

  The phase modulation pixel data output from the imaging unit 30 is sent to the QPSK demodulator 44. The QPSK demodulator 44 demodulates the phase-modulated pixel data into 8-bit error correction pixel data (see error correction pixel data in FIG. 4).

  The error correction pixel data is sent to the error correction demodulation unit 45. The error correction demodulator 45 corrects the information block based on the error correction code from the error correction pixel data. Therefore, the pixel data is corrected for each bit column. Corrected pixel data is generated by the correction.

  The information block component of the corrected pixel data is sent to the image processing unit 46. In the image processing unit 46, predetermined data processing is performed on the pixel data. Further, the pixel data subjected to the predetermined data processing is converted into a pixel signal which is an analog signal, and then sent to the monitor 11 as an image signal of one frame.

  As described above, according to the electronic endoscope 20 and the endoscope processor 40 of the present embodiment, a signal line for sending digital data in the electronic endoscope that generates digital data at the distal end portion of the insertion tube 22. Can be reduced.

  For example, as described above, when a signal is transmitted after being converted into a YCrCb signal in a time-division manner, and when 8-bit digital data is transmitted, a 16-bit signal line is required. On the other hand, in the case of the electronic endoscope 20 of the present embodiment, the number of bits for transmission can be halved by PSK. For this reason, it is possible to reduce the number of signals by half and make a 12-bit signal line while handling RGB pixel data of 8 bits each and handling a total of 24 bits of pixel data.

  Further, since the RGB pixel data is transmitted as it is, it is possible to prevent the image quality from being deteriorated as compared with the case where it is converted into a YCrCb signal and transmitted.

  In this embodiment, the number of bits of pixel data to be transmitted is reduced by four-phase phase modulation, but 2 ^ n phases (n is 2 or more) such as eight-phase phase modulation and 16-phase phase modulation. May be performed.

  In the present embodiment, the color conversion is performed by the RGB conversion unit 34 of the imaging unit 30 and then QPSK modulation is performed. However, error correction modulation and QPSK are performed without performing RGB separation, and the endoscope The processor 40 may be configured to perform color interpolation processing.

  Further, although the present embodiment is configured to perform error correction, error correction modulation need not be performed. However, in the present embodiment in which moving image data of an electronic endoscope is transmitted, since high-speed data communication is performed, an error may occur due to a data delay, and therefore it is preferable that an error correction function is provided.

  In the present embodiment, the QPSK demodulator 44 and the error correction demodulator 45 are provided in the endoscope processor 40, but may be provided in the main body 23 of the electronic endoscope 20. Even in the configuration provided in the main body 23, the number of signal lines provided in the insertion tube 22 which is strongly required to be reduced in diameter can be reduced.

  In the present embodiment, the error correction code is a BCH code or a Reed-Solomon code, but may be any other error correction code.

1 is a block diagram schematically showing an internal configuration of an endoscope system having an electronic endoscope and an endoscope processor to which an embodiment of the present invention is applied. FIG. It is a block diagram which shows the circuit structure of an imaging unit. It is a 1st figure explaining the data structure of the pixel data corresponding to a pixel signal. It is a 2nd figure explaining the data structure of the pixel data corresponding to a pixel signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Endoscope system 20 Electronic endoscope 22 Insertion tube 23 Main body 30 Imaging unit 31 CMOS image sensor 33 A / D converter 34 RGB conversion part 35 Error correction modulation part 36 QPSK modulation part 40 Endoscope processor 44 QPSK demodulation part 45 Error correction demodulator

Claims (7)

An electronic endoscope having an insertion tube connected to the main body,
An image sensor that is provided at the distal end of the insertion tube and receives an optical image of a subject and generates an image signal corresponding to the optical image as an analog signal;
An A / D converter provided at a distal end portion of the insertion tube and converting the image signal into image data which is digital data;
An electronic endoscope, comprising: a PSK modulator provided at a distal end of the insertion tube and performing phase transition modulation of 2 ^ n phase (n is an integer of 2 or more) with respect to the image data.   The electronic endoscope according to claim 1, further comprising a PSK demodulator that is provided in the main body and demodulates the image data phase-modulated by the PSK modulator. An error correction modulation unit that is provided at a distal end of the insertion tube and adds an error correction code to the image data;
The electronic endoscope according to claim 1, wherein the PSK modulation unit performs phase transition modulation on the image data to which the correction code is added.   The electronic endoscope according to claim 3, wherein the correction modulation unit adds an error correction code to the image data in accordance with a block code method.   5. The electronic internal unit according to claim 3, further comprising an error correction demodulating unit that is provided in the main body and corrects an error of the image data to which the correction code is added based on the correction code. Endoscope.   2. An endoscope processor for receiving the image data from the electronic endoscope according to claim 1, further comprising a PSK demodulator for demodulating the image data phase-shift modulated by the PSK modulator. Endoscope processor to do.   The endoscope processor which receives the said image data from the electronic endoscope of Claim 3 or Claim 4, Comprising: The error of the said image acquisition data to which the said correction code was added is corrected based on the said correction code An endoscope processor comprising an error correction demodulating unit for performing the processing.