JP3176126B2 - Signal transmission circuit of electronic endoscope device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission circuit for an electronic endoscope, and more particularly to a signal transmission circuit for transmitting a digitally processed video signal from the electronic endoscope to the processor.

[0002]

2. Description of the Related Art Conventionally, a CCD which is a solid-state imaging device has been used.
2. Description of the Related Art An electronic endoscope apparatus in which a (Charge Coupled Device) is disposed at a distal end of an electronic endoscope (electronic scope) and observes a body cavity such as a digestive tract or a narrow tube of various structures is well known. This electronic endoscope device has a configuration in which the electronic endoscope is connected to an external processor device that performs various kinds of signal processing by a connector. In recent years, however, processing that matches characteristics of individual electronic endoscopes has been performed. In order to facilitate
It has been proposed that image processing such as amplification and gamma processing performed on the video signal obtained in step (1) is mainly performed on the electronic endoscope side. In this case, if the output of the CCD is A (analog) / D (digital) converted and the video signal is digitally processed, good image processing can be performed.

[0003]

However, in the digital processing in the above-mentioned conventional electronic endoscope apparatus, when the video signal is transmitted from the electronic endoscope side to the external processor apparatus, the video signal D is transmitted.
The A / D conversion is required, and the A / D conversion and the D / A conversion are required again in order for the external processor device to store the data in the memory and perform various processes. Therefore, while the output signal of the CCD is output from the processor device to the monitor, the A / D
Since the conversion and the D / A conversion are required twice each, there is a problem that the image quality is reduced and the configuration is useless.

Accordingly, the present applicant has proposed to digitally transmit a video signal from an electronic endoscope to an external processor, but in this case, there are the following problems. That is, FIG. 4 shows the configuration of an electronic endoscope apparatus for digital transmission, and as shown in FIG.
Is provided with a CCD 2 and a first signal processing circuit 3. In the first signal processing circuit 3, the output of the CCD 2 is A / D-converted, image processing such as amplification and gamma processing is performed on the digital video signal, and finally, a luminance signal (Y) and a color signal R are outputted. (Red) -Y, B (blue) -Y color difference signals are obtained. On the other hand, the external processor device 5 is provided with a memory 6 and a second signal processing circuit 7, and converts the video signal stored in the memory 6 into the second signal processing circuit 7 based on the operation condition.
, The image processing corresponding to the operation such as freeze is performed.

However, since the signal output from the first signal processing circuit 3 is a digital signal, the Y signal, the RY color difference signal, and the BY color difference signal are processed in the case of processing with 8-bit data. Since all of the signals are 8 bits, at least 24 transmission lines are required, which complicates the configuration, and the electronic endoscope 1 and the external processor device 5
The connector itself for connecting to the device also becomes large.

The present invention has been made in view of the above problems, and has as its object to reduce the number of transmission lines between an electronic endoscope and a processor by multiplex communication of color difference signals, thereby achieving an economical configuration. It is an object of the present invention to provide a signal transmission circuit of an electronic endoscope apparatus which can perform the above.

[0007]

To achieve the above object, a signal transmission circuit of an electronic endoscope apparatus according to the first aspect of the present invention performs digital image processing on a video signal output from a solid-state imaging device. a digital signal processing circuit for forming a luminance signal and color difference signals by performing, a multiplexer for division multiplex process at a color-difference signal outputted from the digital signal processing circuit, a provided to the electronic endoscope side, the external processor apparatus Is characterized in that a demodulation circuit for demodulating the time-division multiplexed color difference signal is provided, and the luminance signal and the time-division multiplexed color difference signal are transmitted from the electronic endoscope to the processor device side. The invention according to a second aspect is characterized in that the transmission speed of the time-division multiplexed chrominance signal is lower than the transmission speed of the luminance signal. Further, according to the third aspect of the present invention, the electronic endoscope is synchronized with a luminance signal.
The external processor unit a synchronization clock signal synchronized with the synchronous clock signal and time division multiplexed color difference signals to
To be sent to the user.

[0008]

According to the above arrangement, the multiplexer provides
Since the RY and BY color difference signals are mixed by time division multiplexing, the Y signal and the multiplexed color difference signal are transmitted through two lines. In this case, the multiplexed chrominance signal is preferably transmitted at a lower speed than the luminance signal. This makes it easier to perform subsequent signal processing, prevents phase shift during image processing, and improves image quality. Improvement can be achieved.

Further, in the above case, since the synchronous clock synchronized with the luminance signal and the multiplexed color difference signal is simultaneously transmitted to the external processor, the demodulation circuit generates the demodulated signal based on the synchronous clock. The RY signal and the BY signal that are formed and are the color difference signals are accurately demodulated.

[0010]

FIG. 1 shows the configuration of a signal transmission circuit of an electronic endoscope apparatus according to an embodiment, and FIG. 2 shows the overall configuration of the electronic endoscope apparatus. In FIG. 2, an electronic endoscope 10 as a scope is connected to an external processor device 12 by a connector 11, and a CCD 13 is provided at the tip of the electronic endoscope 10, and a light guide 14 is provided. The light guide 14 is connected to the condenser lens 15 and the light source 16 in the external processor device 12,
By controlling the lighting of the light source 16 by the light source control unit 17, irradiation light is supplied to the distal end portion via the light guide 14.

On the other hand, a first signal processing circuit 18 and a microcomputer (microcomputer) 19 are connected to the CCD 13.
3 is read out as a video signal, and this video signal is A / D-converted by the first signal processing circuit 18 and subjected to image digital processing such as amplification and gamma processing. Note that a timing generator 20 is provided in the external processor device 12, and the timing generator 20 forms control signals for various driving.

The first signal processing circuit 18 includes the transmission processing circuit shown in FIG. 1. In the embodiment, a matrix for inputting R, G, and B (mixed signal group) video signals is provided. A circuit 22 and a multiplexer 23 are provided. The matrix circuit 22 converts the R, G, and B video signals into a luminance (Y) signal and an R-Y signal as a color difference signal.
Signal and the BY signal are calculated.
Means time-division multiplexing of the RY signal and the BY signal. That is, the multiplexer 23 is formed in such a manner that the RY signal and the BY signal output from the first signal processing circuit 18 are time-divisionally and alternately inserted without multiplex modulation. Moreover, the time-division multiplexed color difference signal is 1 / fc (for example, fc ≒ 14 MHz) in the luminance signal.
z) The signal is transmitted at half the transmission rate of the cycle, that is, at a rate of 2 / fc, and the microcomputer 19 supplies a signal of 2 / fc to the multiplexer 23 as a synchronous clock signal of the color difference signal.

On the other hand, a demodulation circuit 26 for separating each color difference signal from the multiplexed color difference signal via a memory 25 is provided in the external processor device 12.
Is connected to the second signal processing circuit 27. As for the color difference signal, the microcomputer 19 in the electronic endoscope 10 transmits the above-mentioned synchronous clock and the transmitted signal as the RY signal and the BY signal.
An identification signal for determining whether the signal is one of the signals is supplied to the demodulation circuit 26.
In the RY based on the synchronous clock signal of the color difference signal,
A demodulated signal of the signal and the BY signal is formed.

The embodiment has the above-mentioned configuration, and its operation will be described below with reference to the operation waveforms of FIG. First, FIG.
The illumination light is controlled by the lighting control of the light source 16 of the light guide 1.
The illuminated object image is guided to the distal end portion of the electronic endoscope 10 through 4 and captured by the CCD 13.
Then, the video signal obtained by the CCD 13 is subjected to predetermined image processing such as amplification and gamma correction in a first signal processing circuit 18, and the processed R, G, B signals (each of R, G, B) are processed. The signal group in which the components are mixed) is supplied to the matrix circuit 22.

In the matrix circuit 22, a predetermined operation is performed based on the input signal.
A signal, an RY signal, and a BY signal are formed. And
As for the Y signal, as shown in FIG. 3A, luminance signals Y1, Y2,... Are output at a period of 1 / fc. on the other hand,
The RY signal and the BY signal are input to the multiplexer 23, and the multiplexer 23 performs time division multiplexing. That is, (RY) as shown in FIG.
, (RY) 2, ..., (BY) 1, (BY) 2 ... are formed alternately and sequentially on the time axis at a period of 2 / fc. Therefore, as shown in FIG. 1, only one system (for example, eight transmission lines) is required for the color difference signal, and the video signal can be transmitted in two systems together with the Y signal.

In the present invention, the color difference signal is transmitted at half the speed of the Y signal. This is to reduce the transmission speed by focusing on the fact that the band of the color difference signal is narrower than the band of the Y signal in order to facilitate later signal processing. That is, if the transmission speed is reduced, there is an advantage that the separation of the color difference signals at the time of demodulation becomes easy, and the phase shift is easily managed in the subsequent signal processing. Moreover, since the chrominance signal of the embodiment is not multiplex-modulated, there is an advantage that it is not necessary to manage the phase of the subcarrier in the subsequent signal processing.

In this manner, the Y signal, the RY signal, and the BY signal are transmitted to the external processor device 12 in two systems, and the demodulation circuit 26 (via the memory 25) in the external processor device 12 is provided. , But at the same time,
The synchronous clock of the luminance signal of FIG. 3C, the synchronous clock of the color difference signal of FIG. 3D, and the identification signal of FIG. 3E are supplied to the external program device 12 via the control line. Then, by the synchronous clock of the color difference signal, FIG.
And the BY demodulated signal shown in FIG. 7G are formed, and the color difference signal is separated from the multiplexed signal shown in FIG. That is, an intermediate portion of each color difference signal is detected by the RY demodulated signal and the BY demodulated signal, and is latched, whereby the RY signal shown in FIG. The indicated BY signal is extracted. Note that a demodulated signal is similarly formed from the synchronous clock for the luminance signal, and the luminance signal is demodulated.

The demodulated Y signal, RY
The signal and the BY signal are supplied to the monitor after being subjected to processing for outputting to the monitor by the second signal processing circuit 27.

In the above embodiment, the time division multiplexed signal is transmitted at half the transmission speed of the Y signal.
It is sufficient that the transmission speed is equal to or lower than the transmission speed of the Y signal.

[0020]

As described above, according to the first aspect of the present invention, a luminance signal and a chrominance signal are formed by digital image processing, and the chrominance signal is subjected to time-division multiplexing processing to an external processor. Since the transmission is performed, the digital video signal can be transmitted through two transmission lines, so that the transmission lines can be simplified and the number of connectors can be reduced. Moreover, by transmitting the digital signal, it is not necessary to perform the analog-digital conversion again, so that the image quality can be prevented from deteriorating and the configuration of the entire apparatus can be simplified.

According to the second aspect of the present invention, the transmission rate of the time-division multiplexed color difference signal is made slower than the transmission rate of the luminance signal, so that the processing of the color difference signal after transmission becomes easy. There is an advantage that the management of the phase matching is simplified.

Further, according to the third aspect of the present invention, the electronic
The time-division multiplexed color difference signals from the viewing mirror to an external processor device, than you sent <br/> a synchronization clock signal synchronized with the luminance signal, the advantage that demodulation processing of the color difference signal can be easily and accurately is there.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a signal transmission circuit of an electronic endoscope apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an overall configuration of the electronic endoscope apparatus according to the embodiment.

FIG. 3 is a signal waveform diagram showing the operation of the circuit of the embodiment.

FIG. 4 is a block diagram schematically showing a conventional electronic endoscope apparatus.

[Explanation of symbols]

 1,10 ... electronic endoscope, 2,13 ... CCD, 3,18 ... first signal processing circuit, 5,12 ... external processor device, 7,27 ... second signal processing circuit, 19 ... microcomputer, 22 ... matrix Circuit, 23 ... multiplexer, 26 ... demodulation circuit.

Claims (3)

(57) [Claims] 1. A digital signal processing circuit for performing digital image processing on a video signal output from a solid-state imaging device to form a luminance signal and a color difference signal, and time-division multiplexing the color difference signal output from the digital signal processing circuit. And a multiplexer for processing are provided on the electronic endoscope side, and an external processor device is provided.
The location provided on the side of the demodulation circuit for demodulating the time division multiplexed color difference signals, the electronic endoscope which is adapted to transmit the color difference signals the luminance signal and the time division multiplexed from the electronic endoscope to the processor apparatus Signal transmission circuit of mirror device. 2. The signal transmission circuit according to claim 1, wherein the transmission rate of the time-division multiplexed color difference signal is lower than the transmission rate of the luminance signal. 3. The electronic endoscope is synchronized with a luminance signal.
The electronic endoscope of the first claim, wherein the synchronized clock signal so as to <br/> sent to the external processor unit to synchronize to that synchronizing clock signals and time division multiplexed color difference signals The signal transmission circuit of the device.