JP6741412B2 - Signal transmission device and electronic endoscope system - Google Patents

Description

The present invention relates to a signal transmission device and an electronic endoscope system.

The electronic scope provided in the electronic endoscope system is required to be minimally invasive in order to reduce the burden on the patient. As a method of improving the minimally invasiveness, it is conceivable to reduce the diameter of the electronic scope by reducing the number of signal cables in the electronic scope. As an example, it is possible to reduce the number of signal cables by adopting a configuration in which various necessary signals are time-division-multiplexed, converted into serial signals, and the converted serial signals are transmitted by signal cables.

When the above configuration is adopted, it is necessary to transmit the serial signal at a high frequency in order to secure the transmission speed. However, because of problems such as crosstalk and unnecessary radiation, the transmission frequency cannot be raised easily.

Therefore, for example, Patent Document 1 describes a configuration for transmitting a multilevel signal instead of a serial signal. In the configuration described in Patent Document 1, the transmitting side converts each amplitude of the plurality of digital input signals into a voltage (multilevel signal) according to a predetermined weighting, adds the converted voltages, and transmits the voltage. Compares the received signal with each reference voltage and restores the digital input signal according to the comparison result. By adopting such a configuration, it is possible to increase the transmission speed while suppressing the transmission frequency.

JP, 2008-125124, A

In general, since the signal cable routed inside the electronic scope has a long overall length and a small diameter, the influence of reflection and voltage drop cannot be ignored. Further, the signal cable routed inside the electronic scope cannot ignore a change in impedance and a change in capacitance when the flexible cable of the electronic scope is bent along with bending. Therefore, when the configuration described in Patent Document 1 is adopted in the electronic endoscope system, the digital input signal may not be properly restored on the receiving side due to the influence of voltage drop, noise, and the like.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a signal transmission suitable for increasing the transmission speed while suppressing the transmission frequency even though the number of signal cables is suppressed. An apparatus and an electronic endoscope system are provided.

A signal transmission device according to an embodiment of the present invention is set between a signal level and a multilevel signal output unit that outputs a multilevel signal indicating a test pattern, a transmission line that transmits the output multilevel signal, and a signal level. Based on the result of the comparison by the restoring means for restoring the test pattern from the multilevel signal transmitted by the transmission path using a plurality of thresholds, the comparing means for comparing the restored test pattern and the reference pattern, and the comparing means. Adjusting means for adjusting the threshold value.

Further, in the embodiment of the present invention, the adjusting unit may be configured to adjust the threshold value so that the test pattern restored by the restoring unit matches the reference pattern.

In one embodiment of the present invention, the multilevel signal output means outputs the multilevel signal at a predetermined timing, for example.

The predetermined timing is, for example, the start of power supply to the signal transmission device.

Further, the signal transmission device according to the embodiment of the present invention may be configured to include a video signal output unit that outputs a video signal. In this case, the multilevel signal output means outputs the multilevel signal during the blanking period of the video signal, for example.

An electronic endoscope system according to an embodiment of the present invention is a system in which the above signal transmission device is incorporated.

According to an embodiment of the present invention, there is provided a signal transmission device and an electronic endoscope system which have a configuration in which the number of signal cables is suppressed and which are suitable for increasing the transmission speed while suppressing the transmission frequency.

It is a block diagram showing composition of an electronic endoscope system concerning one embodiment of the present invention. It is a figure which illustrates the relationship between a digital image signal and a multilevel signal in one embodiment of the present invention. It is a figure which illustrates the waveform of the multilevel signal corresponding to FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, an electronic endoscope system will be described as an example of an embodiment of the present invention.

FIG. 1 is a block diagram showing the configuration of an electronic endoscope system 1 according to an embodiment of the present invention. As shown in FIG. 1, the electronic endoscope system 1 is a system specialized for medical use, and includes an electronic scope 100, a processor 200, and a monitor 300.

The processor 200 includes a controller unit 202 and a timing controller 204. The controller unit 202 has a CPU (Central Processing Unit) 202a. The CPU 202a executes various programs stored in the memory 212 and integrally controls the entire electronic endoscope system 1. The CPU 202a is also connected to the operation panel 214. The CPU 202a changes each operation of the electronic endoscope system 1 and parameters for each operation according to an instruction from the operator input from the operation panel 214. The timing controller 204 outputs a clock pulse for adjusting the operation timing of each unit to each circuit in the electronic endoscope system 1.

The lamp 208 emits the irradiation light L after being started by the lamp power igniter 206. The lamp 208 is, for example, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, a metal halide lamp, or an LED (Light Emitting Diode). The irradiation light L is light (or white light including at least the visible light region) having a spectrum that mainly spreads from the visible light region to the invisible infrared light region.

The irradiation light L emitted from the lamp 208 is condensed by the condenser lens 210 on the incident end face of the LCB (Light Carrying Bundle) 102 and is incident on the inside of the LCB 102.

The irradiation light L incident on the LCB 102 propagates inside the LCB 102. The irradiation light L propagating in the LCB 102 is emitted from the emission end surface of the LCB 102 arranged at the tip of the electronic scope 100, and is irradiated to the subject through the light distribution lens 104. The return light from the subject illuminated by the illumination light L forms an optical image on the light receiving surface of the solid-state image sensor 106 via the objective lens 105.

The solid-state image sensor 106 is a single-chip color CMOS (Complementary Metal Oxide Semiconductor) image sensor having a Bayer type pixel arrangement. The solid-state imaging device 106 accumulates the optical image formed by each pixel on the light-receiving surface as electric charges according to the amount of light, and outputs R (Red), G (Green), and B (Blue) image signals (video signals). Is generated and output to the A/D converter 107. The solid-state imaging device 106 is not limited to the CMOS image sensor, and may be replaced with a CCD (Charge Coupled Device) image sensor or another type of imaging device. The solid-state image sensor 106 may also be equipped with a complementary color filter.

The A/D converter 107 AD-converts the analog image signal input from the solid-state image sensor 106 with a resolution of n bit (n is 2 or more). The A/D converter 107 outputs the digital image signal obtained by the AD conversion to the multilevel signal generation circuit 108. The A/D converter 107 may be built in the solid-state image sensor 106.

The multi-level signal generation circuit 108 weights the n-bit digital image signal input from the A/D converter 107, and outputs analog information (more specifically, voltage (multi-level signal)) having n-bit information. To generate.

FIG. 2 illustrates the relationship between the digital image signal and the multilevel signal. In the example of FIG. 2, the A/D converter 107 outputs a 2-bit digital image signal of Ai and Bi. As illustrated in FIG. 2, the multi-level signal conversion circuit 108 outputs 0 V when digital information of Ai=0 and Bi=0 is input, and digital information of Ai=0 and Bi=1 is input. Then, 1V is output, 2V is output when digital information of Ai=1 and Bi=0 is input, and 3V is output when digital information of Ai=1 and Bi=1 is input.

The multilevel signal output from the multilevel signal generation circuit 108 is transmitted by the signal cable 109 and input to the driver signal processing circuit 110. The driver signal processing circuit 110 outputs the multilevel signal input from the solid-state image sensor 106 to the pre-stage signal processing circuit 220 of the processor 200.

The driver signal processing circuit 110 also accesses the memory 112 to read the unique information of the electronic scope 100. The unique information of the electronic scope 100 recorded in the memory 112 includes, for example, the number of pixels and sensitivity of the solid-state imaging device 106, operable frame rate, model number, and the like. The driver signal processing circuit 110 outputs the unique information read from the memory 112 to the CPU 202a. In the following description, "frame" may be replaced with "field". In this embodiment, the frame period and the field period are 1/30 second and 1/60 second, respectively.

The CPU 202a performs various calculations based on the unique information of the electronic scope 100 to generate a control signal. The CPU 202a uses the generated control signal to control the operation and timing of various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed.

The timing controller 204 supplies a clock pulse to the driver signal processing circuit 110 according to the timing control by the CPU 202a. The driver signal processing circuit 110 drives and controls the solid-state imaging device 106 at a timing synchronized with the frame rate of the image processed on the processor 200 side in accordance with the clock pulse supplied from the timing controller 204.

The pre-stage signal processing circuit 220 has a comparator 220a and a pre-stage processing unit 220b. The comparator 220a restores the multi-level signal input from the driver signal processing circuit 110 into an n-bit digital image signal according to the voltage level (signal level).

Specifically, the comparator 220a has a plurality of threshold values set between voltage levels. In the example of FIG. 2, the threshold values are set to 0V, 0.5V, 1.5V, 2.5V and 3.5V. As a result, the comparator 220a restores a multi-valued signal higher than 0V and less than 0.5V into a digital image signal of Ai=0, Bi=0, and outputs a multi-valued signal of 0.5V or more and less than 1.5V. Restore a digital image signal of Ai=0, Bi=1, restore a multi-valued signal of 1.5 V or more and less than 2.5 V to a digital image signal of Ai=1, Bi=0, and restore a digital image signal of 2.5 V or more. A multi-valued signal of less than 3.5V is restored to a digital image signal of Ai=1 and Bi=1.

The digital image signal restored by the comparator 220a is input to the pre-processing unit 220b. The pre-processing unit 220 b performs predetermined signal processing such as demosaic processing, matrix calculation, Y/C separation on the input digital image signal, and outputs the signal to the post-signal processing circuit 230.

The post-stage signal processing circuit 230 processes the image signal input from the pre-stage processing unit 220b to generate screen data for monitor display, and converts the generated screen data for monitor display into a predetermined video format signal. The converted video format signal is output to the monitor 300. As a result, a color image of the subject is displayed on the display screen of the monitor 300.

Here, since the signal cable 109 is routed inside the flexible tube of the electronic scope 100 designed to have a small diameter, it has a long overall length and a small diameter. Therefore, in the signal cable 109, the influence of reflection and voltage drop cannot be ignored.

FIG. 3 illustrates the waveform of the multilevel signal corresponding to FIG. FIG. 3A illustrates an ideal waveform of the multilevel signal, and FIG. 3B illustrates a waveform of the multilevel signal at the time of input to the comparator 220a. Even if the multilevel signal has an ideal waveform (see FIG. 3A) at the time of output from the multilevel signal generation circuit 108, it is affected by reflection and voltage drop during transmission of the signal cable 109, and thus the comparator At the time of input to 220a, the ideal waveform is disturbed (see FIG. 3B). In this case, if the threshold value set in the comparator 220a is set to a value corresponding to the ideal waveform, the digital image signal may not be restored correctly.

Therefore, the electronic endoscope system 1 according to the present embodiment appropriately sets the threshold value of the comparator 220a so that the digital image signal can be correctly restored even when the multilevel signal is disturbed with respect to the ideal waveform. It has a configuration that can be adjusted.

Specifically, the electronic scope 100 is provided with a test pattern generation circuit 111 that generates a prescribed test pattern. When the power of the electronic endoscope system 1 is turned on and the supply of power to various circuits is started, the test pattern generation circuit 111 outputs a test pattern to the A/D converter 107. The A/D converter 107 converts the test pattern input from the test pattern generation circuit 111 into a digital signal (hereinafter referred to as “digital test pattern”) and outputs the digital signal to the multilevel signal generation circuit 108. The multilevel signal generation circuit 108 generates a multilevel signal indicating a test pattern based on the digital test pattern input from the A/D converter 107. The generated multilevel signal is input to the comparator 220a via the signal cable 109 and the driver signal processing circuit 110.

The controller unit 202 has a digital comparator 202b. The digital comparator 202b holds in advance a reference pattern that matches the digital test pattern.

The digital test pattern restored by the comparator 220a is input to the digital comparator 202b. The digital comparator 202b compares the input digital test pattern with the reference pattern and outputs the comparison result to the CPU 202a.

The CPU 202a adjusts each threshold value set in the comparator 220a until the comparison result between the digital test pattern restored by the comparator 220a and the reference pattern matches. By completing the adjustment of the threshold value, even if the waveform of the multilevel signal transmitted through the signal cable 109 is disturbed with respect to the ideal waveform, the digital test pattern and the digital image signal are correctly restored from the multilevel signal. Like

That is, according to the present embodiment, the original digital signal can be correctly restored on the receiving side (comparator 220a) from the multilevel signal transmitted on the transmission line (signal cable 109) in which the waveform is easily disturbed. It is suitable for increasing the transmission speed while suppressing the transmission frequency even though the number of lines is suppressed.

Further, in the electronic endoscope system 1, generally, one electronic scope 100 selected from a plurality of electronic scopes 100 according to a diagnostic purpose or a situation is used by being connected to a common processor 200. In this case, since the total length, diameter, and type of the signal cable 109 differ depending on the model of the electronic scope 100, the waveform disturbance at the time of input to the comparator 220a also varies depending on the model of the electronic scope 100. On the other hand, the CPU 202a can properly restore the original digital signal from the multilevel signal regardless of the degree of the waveform disturbance by appropriately adjusting the thresholds of the comparator 220a. That is, the processor 200 is able to correctly restore the original digital signal from the multilevel signal without depending on the model of the electronic scope 100, and thus has high versatility.

The above is a description of exemplary embodiments of the present invention. The embodiments of the present invention are not limited to those described above, and various modifications are possible within the scope of the technical idea of the present invention. For example, the contents of an embodiment of the present application also include appropriate combinations of the embodiments and the like explicitly described in the specification or the obvious embodiments and the like.

In the above embodiment, the test pattern generation circuit 111 outputs the test pattern when the electronic endoscope system 1 is powered on and power supply to various circuits is started. The timing is not limited to this.

For example, the operation of the electronic endoscope system 1 such as when the impedance changes due to the bending of the signal cable 109, when the capacitance changes, when a high-frequency treatment tool is used, or when the usage environment such as temperature changes. It is conceivable that the waveform of the multilevel signal changes greatly. Therefore, the test pattern generation circuit 111 may output the test pattern during the blanking period of the image signal (video signal) output from the solid-state image sensor 106. That is, by superimposing the test pattern in the blanking period and transmitting it by the signal cable 109, it is possible to cause the CPU 202a to sequentially adjust the threshold of the comparator 220a according to the test pattern without affecting the video signal. Therefore, even when the waveform of the multilevel signal largely changes during the operation of the electronic endoscope system 1, the original digital signal can be correctly restored from the multilevel signal.

The test pattern may be output for each blanking period (for each frame), or for each m blanking period (for each m frame, where m is 2 or more).

1 Electronic Endoscope System 100 Electronic Scope 102 LCB
104 Light distribution lens 105 Objective lens 106 Solid-state image sensor 107 A/D converter 108 Multi-level signal generation circuit 109 Signal cable 110 Driver signal processing circuit 111 Test pattern generation circuit 112 Memory 200 Processor 202 Controller unit 202a CPU
202b Digital comparator 204 Timing controller 206 Lamp power igniter 208 Lamp 210 Condenser lens 212 Memory 214 Operation panel 220 Pre-stage signal processing circuit 220a Comparator 220b Pre-stage processing unit 230 Post-stage signal processing circuit

Claims (3)

Video signal output means for outputting a video signal,
A multilevel signal output means for outputting a multilevel signal indicating a test pattern,
A transmission path for transmitting the video signal output from the video signal output means and the multi-valued signal output from the multi-valued signal output means;
Restoration means for restoring the test pattern from the multilevel signal transmitted by the transmission path using a plurality of thresholds set between signal levels,
Comparing means for comparing the restored test pattern with the reference pattern,
Adjusting means for adjusting the threshold value based on the result of the comparison by the comparing means,
Equipped with
The multilevel signal output means,
Outputting the multi-valued signal every m (m is 2 or more) blanking period of the video signal,
Signal transmission equipment. The adjusting means,
The threshold is adjusted so that the test pattern restored by the restoring unit matches the reference pattern,
The signal transmission device according to claim 1. The signal transmission device according to claim 1 or 2 is incorporated,
Electronic endoscopy system.

Images