JP3935993B2 - Electronic endoscope device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope apparatus in which an observation image of an endoscope is picked up by a solid-state image pickup device in a frame sequential manner.
[0002]
[Prior art]
2. Description of the Related Art In a field sequential electronic endoscope apparatus, a solid-state image sensor generally captures a subject that is sequentially illuminated by three colors of red (R), green (G), and blue (B) illumination light. . Each color video signal obtained by shifting the time is converted into a digital signal and temporarily stored in a memory for each color video signal. Each color video signal is simultaneously read from each memory, converted into an analog signal, and then output.
[0003]
[Problems to be solved by the invention]
As described above, the conventional electronic endoscope apparatus requires three memories for temporarily storing video signals in order to synchronize the video signal output for each of the three colors, which increases the circuit scale. This has led to an increase in equipment size and cost.
[0004]
Accordingly, an object of the present invention is to provide an electronic endoscope apparatus capable of reducing the cost by reducing the scale of a circuit for processing a signal imaged in a frame sequential manner by a solid-state imaging device.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus in which an observation image of an endoscope is imaged in a surface sequential manner by a solid-state imaging device. The color-coded video signals that are captured and output sequentially are converted into digital signals, and then each color video signal is dot-sequentially stored in the same memory and temporarily stored. After conversion to an analog signal, all or part of the color-specific analog video signal is delayed for different times to synchronize the output of each color video signal.
[0006]
The means for delaying the color-specific analog signal may be a delay circuit or a low-pass filter having a predetermined delay characteristic. Further, the video signal for each color may be a video signal of the three primary colors of the additive color mixing method.
[0007]
The memory may be a frame memory for storing one frame of video signal or a field memory for storing one field of video signal.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 2 shows the overall configuration of the electronic endoscope apparatus according to the embodiment of the present invention. In the imaging position of the subject by the objective optical system 3 provided at the distal end of the insertion portion 2 of the endoscope 1. For example, a solid-state imaging device 4 made of a charge coupled device (CCD) is disposed. Reference numeral 5 denotes a light guide fiber bundle for transmitting illumination light that illuminates the observation range.
[0009]
The connector section 6 of the endoscope 1 connected to the video processor 10 stores a drive circuit 7 that performs amplification and the like of signals input to and output from the solid-state imaging device 4 and data unique to the endoscope 1. A rewritable read-only memory (EEPROM) 8 is arranged.
[0010]
The video processor 10 also serves as an illumination light source device for illuminating a subject, and illumination light is incident on the light guide fiber bundle 5 of the endoscope 1 from the light source lamp 11.
[0011]
In the middle of the incident optical path, a three-color rotation filter 12 to which three color filters of red (R), green (G), and blue (B) are attached is arranged so as to rotate at a constant speed. Red, green, and blue illumination lights are sequentially incident on the guide fiber bundle 5 at different times.
[0012]
The output end of the CCD process unit 14 connected to the drive circuit 7 of the solid-state imaging device 4 is connected to the input end of the video process unit 16 via the timing circuit 15, and the output signal from the video process unit 16 is monitored. 18 is sent.
[0013]
The operations of the CCD process unit 14, the timing circuit 15 and the video process unit 16 are controlled in conjunction with each other by a system control unit 17 having a central processing unit (CPU). Further, endoscope-side data is read from the EEPROM 8 connected thereto via the peripheral driver 19 connected to the system control unit 17.
[0014]
FIG. 1 specifically shows the configuration of the CCD process unit 14 and the video process unit 16 described above.
In the CCD process unit 14, the additive primary color image signal output from the solid-state image sensor 4 is amplified by the amplifier 23, and then the image signal is extracted by the sample and hold circuit 24. Is converted into a digital signal.
[0015]
The digitized video signal is input to one memory 26 in synchronization with driving of the solid-state imaging device 4 by the timing circuit 15 and temporarily stored in the memory 26.
[0016]
In the memory 26, as schematically shown in FIG. 3, addresses are designated in advance so that digital video signals of three colors of red (R), green (G), and blue (B) are repeatedly stored. The video signals for each of the three colors sent sequentially by the frame sequential method are dot-sequentially stored on one horizontal line and then sequentially output. FIG. 3 illustrates a part of the storage capacity of the memory 26 for explaining the operation.
[0017]
Thus, the digital video signal sequentially output after being dot-sequential in the memory 26 is branched into three systems, and the same signal is converted into three digital / analog converters 27R and 27G for red, green and blue. , 27B. The memory 26 is a so-called frame memory or field memory, and stores video signals by color for one screen (one frame or one field).
[0018]
The digital / analog converters 27R, 27G, and 27B are supplied with clock pulses RCLK, GCLK, and BCLK, which are independent of each other, from the timing circuit 15.
[0019]
Then, in each color digital-analog converter 27R, 27G, 27B, as shown in FIG. 4, only the data corresponding to each color is sampled by the timing of the input clock pulse, and in the red digital-analog converter 27R. The red digital video signal is converted into an analog signal, the green digital analog converter 27G converts the green digital video signal into an analog signal, and the blue digital analog converter 27B converts the blue digital video signal into an analog signal. Is done.
[0020]
As shown in FIG. 4, the red (R), green (G), and blue (B) analog video signals output from the digital-analog converters 27R, 27G, and 27B for each color in this manner are temporally related. There is a gap.
[0021]
Therefore, delay circuits 28G and 28B for synchronizing three-color video signals are connected to the output lines of the digital analog converters 27G and 27B for green and blue. In order to synchronize the color video signals, the delay amount of the green video signal is set larger than the delay amount of the blue video signal.
[0022]
With this configuration, as shown in FIG. 5, the video signals of three colors of red (R), green (G), and blue (B) are synchronized, and each removes high-frequency noise. It is output after passing through low-pass filters 29R, 29G, and 29B. Here, the output of the video signal of two colors out of the three colors is delayed, but all the video signals of the three colors may be delayed.
[0023]
The present invention is not limited to the above embodiment. For example, if the delay characteristics of the low-pass filters 29R, 29G, and 29B are set to have different delay amounts for the respective color signals as shown in FIG. As shown in FIG. 7, the output of the three-color video signal can be synchronized without providing an independent delay circuit.
[0024]
【The invention's effect】
According to the present invention, digital video signals by color obtained by imaging in a frame sequential method are dot-sequentially stored in the same memory, temporarily stored, and after converting each color video signal to an analog signal, different times for each color. Since the delays are synchronized, the number of signal lines required for processing with, for example, 10 bits can be reduced from the conventional 30 to 10, and the circuit scale can be reduced and the cost can be reduced. Can do.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of a first embodiment.
FIG. 2 is a block diagram showing an overall configuration of the electronic endoscope apparatus according to the first embodiment.
FIG. 3 is a schematic diagram showing the contents stored in the memory according to the first embodiment;
FIG. 4 is a time chart showing digital-to-analog conversion characteristics of the first embodiment.
FIG. 5 is a time chart showing an analog video signal output of the first embodiment.
FIG. 6 is a diagram showing delay characteristics of the low-pass filter according to the second embodiment.
FIG. 7 is a circuit block diagram of a second embodiment.
[Explanation of symbols]
4 Solid-state image sensor 26 Memory 27R, 27G, 27B Digital / analog converter 28G, 28B Delay circuit

Claims (5)

In an electronic endoscope apparatus in which an observation image of an endoscope is picked up by a solid-state image pickup device in a field sequential method using three colors of RGB ,
After converting each digital signal of RGB three colors Color field sequential image signals sequentially output is captured by the solid-state imaging device, the respective color video signals of the RGB three colors, each color in serialization points in different colors in order in dot units of the video signal temporarily stored in the same memory, after the Lud digital video signals are sequentially outputted from the memory into an analog signal by the RGB three colors, all of the color analog video signal Alternatively, the electronic endoscope apparatus is characterized in that each color video signal output is synchronized by delaying a part thereof for different times. 2. The electronic endoscope apparatus according to claim 1, wherein the means for delaying the color-specific analog signal is a delay circuit. 2. The electronic endoscope apparatus according to claim 1, wherein the means for delaying the color-specific analog signal is a low-pass filter having a predetermined delay characteristic. 4. The electronic endoscope apparatus according to claim 1, wherein the video signal for each color is a video signal of three primary colors according to an additive color mixing method. 5. The electronic endoscope apparatus according to claim 1, wherein the memory is a frame memory for storing a video signal of one frame or a field memory for storing a video signal of one field.

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