JPH064060B2 - Electronic endoscopic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic endoscope apparatus having a solid-state image pickup device provided at the tip of an insertion portion of an endoscope, and particularly, by an external signal processing apparatus, The present invention relates to compensation of waveform distortion when a drive pulse is transmitted to a solid-state image sensor in an electronic endoscope apparatus that generates a drive pulse to the solid-state image sensor and processes a signal obtained from the solid-state image sensor.

[Conventional technology]

In recent years, with the development of solid-state imaging devices, a display device in which a solid-state imaging device such as a charge-coupled device (CCD) is built into the tip of an endoscope to capture an image inside a body cavity and an image from the solid-state imaging device is provided outside Electronic endoscopes for displaying have been developed.

Usually, the light source of the endoscope is provided as a light source device separate from the main body, and the endoscope is connected to the light source device via a light source connector branched from the main body. Then, the illumination light from the light source device is applied to the subject through the light guide fiber.

In the electronic endoscope as described above, a drive pulse generating circuit that generates a drive pulse for driving the solid-state image sensor, a video processing circuit that processes an image signal from the solid-state image sensor, and the like are required. Like the light source device, these circuit units are provided in a video processor separate from the endoscope body. The drive pulse to the solid-state image sensor is supplied to the solid-state image sensor via a signal line in the endoscope body.

In general, endoscopes are available in various lengths and diameters depending on the insertion site, so that such a circuit unit can be commonly used for any type of electronic endoscope,
The same solid-state image sensor is used for all types of electronic endoscopes. However, if the length of the endoscope is different, the distance of the signal line from the circuit unit in the light source device to the solid-state image sensor at the tip of the endoscope is also different accordingly, and the following problems occur. Generally, when the length of the signal transmission line becomes long, the waveform of the clock pulse supplied from the drive circuit to the solid-state image pickup device is distorted, the waveform is not an accurate rectangular waveform, and the solid-state image pickup device cannot be driven accurately. The influence of the distortion of the waveform during the transmission of this signal varies depending on the length of each endoscope, so that it is impossible to connect a plurality of electronic endoscopes having different lengths to one drive circuit. .

Therefore, conventionally, with the configuration shown in FIG. 3, the waveform distortion of the clock pulse due to the length of the endoscope, that is, the distance of the signal line from the video processor to the solid-state image sensor at the tip of the endoscope is compensated. Was.

A charge-coupled device (CCD) 12 as a solid-state image sensor is built in the tip of the endoscope 10 to image the inside of a body cavity. Endoscope
Illumination light from a light source device 14 separate from 10 illuminates the inside of the body cavity via a light guide fiber 16.
The light source device 14 has a light source lamp 18 and a lens 20 for condensing the light from the lamp 18 on the end portion of the light guide fiber 16.

On the other hand, the signal obtained from the CCD 12 at the tip of the endoscope 10 is supplied to the video signal processing circuit 28 via the differential amplifier 26 in the video processor 24. The output of the video signal processing circuit 28 is displayed on the display device (eg, CRT display) 30.

The video processor 24 further includes a drive pulse generation circuit 32 and a constant voltage power supply circuit 34. The output signal of the constant voltage power supply circuit 34 is supplied to the CCD 12 as the substrate bias voltage Vsub. The drive pulse generation circuit 32 uses a horizontal drive pulse φ
H ₁ , φH ₂ , reset pulse φR, vertical drive pulse φ
V ₁ and φV ₂ are generated. Horizontal drive pulse φH ₁ , φH
₂ , reset pulse φR, vertical drive pulse φV ₁ , φV
₂ is supplied to the CCD 12 through the horizontal drive circuits 40 and 42, the reset pulse drive circuit 44, and the vertical drive circuits 46 and 48, respectively. Each drive circuit 40, 42, 44, 46, 48 is a circuit that amplifies the voltage of each pulse to a predetermined voltage.

Since the waveforms of the horizontal drive pulses φH ₁ and φH ₂ and the reset pulse φR are distorted during the transmission of the signal line, they are supplied to the waveform compensating circuits 50, 52 and 54 for preliminarily compensating for the waveform distortion. The waveform compensating circuits 50, 52 and 54 differentiate the input pulse and superimpose the distortion component during signal transmission on the drive pulse, whereby the drive pulse becomes an accurate rectangular wave when reaching the CCD 12. Here, in order to enable the video processor 24 to connect to a plurality of endoscopes of different types (lengths),
Each waveform compensation circuit comprises a plurality of differentiating circuits with different time constants. The input pulse is input to each differentiating circuit, the outputs of all the differentiating circuits are supplied to the switching circuits 56, 58, 60, and one of the signals is determined by the endoscope type (length) discrimination signal (not shown). Is selected. Switching circuit 56, 58, 60
Includes a relay switch connected to the output of each differentiating circuit.

Vertical drive pulses φV ₁ and φV ₂ are horizontal drive pulses φ
Since the signal has a frequency lower than that of H ₁ , φH ₂ , and reset pulse φR, the influence of waveform distortion during transmission of the signal line is small, and therefore a waveform compensation circuit is not provided here.

[Problems to be solved by the invention]

However, according to this conventional example, if the type of endoscope is n
In terms of types, 3n differentiating circuits and 3n relay switches are required, which leads to an increase in size of the video processor 24, resulting in high cost.

Furthermore, the DC voltage (Vsub) supplied to the CCD 12 is CC
The optimum voltage value varies from element to element due to manufacturing variations in D. However, in the past, this was ignored and the voltage was set to a typical value, so that the performance of the CCD 12 could not be fully exhibited.

This invention has been made to deal with the above-mentioned circumstances,
The purpose is to compensate the distortion of the waveform of the drive pulse with a simple configuration in the electronic endoscope apparatus as described above.

[Means for solving problems]

The electronic endoscope apparatus according to the present invention is for an endoscope having a solid-state image sensor at the tip, a light source apparatus for generating illumination light for illuminating an observation site, and a light source apparatus for connecting the endoscope and the light source apparatus. By connecting the connector, the signal processing device that generates a drive pulse of the solid-state imaging device and processes the signal output from the solid-state imaging device, and the light source device connector and the signal processing device, the light source device connector is formed. A signal processing device connector for connecting an endoscope and a signal processing device via a light source device, and a light source device connector. The waveform compensating means is provided in advance to compensate for drive pulse and waveform distortion during transmission to the solid-state imaging device. And is provided.

[Action]

According to the electronic endoscope apparatus of the present invention, since the waveform compensating means is provided in the light source connector of the endoscope, any endoscope can be connected to the common signal processing apparatus. Moreover, since this waveform compensating means is unique to the endoscope, it has a simple structure.

〔Example〕

An embodiment of an electronic endoscope apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the first embodiment. The first embodiment comprises an endoscope 10, a light source device 14, a video processor 24, and a display device 30. The endoscope 10 is a light source device 1
4, the video processor 24 and the light source connector 66,
Connected via the processor connector 68. The signal line from the video processor 24 is connected to the CCD 12 through the processor connector 68 and the light source connector 66. A display device (eg, CRT display) 30 is connected to the video processor 24.

Light from the light source lamp 18 in the light source device 14 is incident on the light guide fiber 16 through the condenser lens 20, is guided to the tip of the endoscope 10 through the light guide fiber 16, and illuminates the inside of the body cavity.

A signal obtained from the CCD 12 at the tip of the endoscope 10 is supplied from the light source connector 66 to the video processor 24 via the processor connector 68 and to the video signal processing circuit 28 via the differential amplifier 26. The output of the video signal processing circuit 28 is displayed on the display device 30.

The video processor 24 further includes a drive pulse generation circuit 32 and a constant voltage power supply circuit 34. The output signal Vo of the constant voltage power supply circuit 34 is supplied to the variable voltage power supply circuit 76 in the light source connector 66 via the processor connector 68. The output Vsub of the variable voltage power supply circuit 76 is used as the substrate bias voltage in CCD1.
Supplied to 2. The variable voltage power supply circuit 76 is adjusted so as to generate a substrate bias voltage specific to the CCD 12 by adjusting an external variable resistor r.

The drive pulse generating circuit 32 uses horizontal drive pulses φH ₁ and φ
H ₂ , reset pulse φR, vertical drive pulse φV ₁ , φ
Generate V ₂ . The vertical drive pulses φV ₁ and φV ₂ are amplified to predetermined voltages via the vertical drive circuits 46 and 48, respectively, and then supplied from the processor connector 68 to the CCD 12 via the light source connector 66.

The horizontal drive pulses φH ₁ and φH ₂ and the reset pulse φR are supplied to the light source connector 66 through the processor connector 68, and the horizontal drive circuits 40 and 42 and the reset drive circuit 44 among them are supplied.
Are amplified to a predetermined voltage. The outputs of the horizontal drive circuits 40, 42 and the reset drive circuit 44 are supplied to the differentiating circuits 70, 72, 74 for waveform compensation, respectively, and the waveform distortion is compensated in advance. The time constant of the differentiating circuit 70, 72, 74 is the endoscope 10
Is determined according to the length of. The outputs of the differentiating circuits 70, 72, 74 are supplied to the CCD 12.

Thus, according to the first embodiment, since the light source connector 66 is provided with the differential circuits 70, 72 and 74 for waveform compensation of the horizontal drive pulses φH ₁ and φH ₂ and the reset pulse φR,
The waveform distortion is compensated for each endoscope. Further, since this compensation circuit is unique to the endoscope, it has a simple configuration.
Therefore, it is not necessary to provide three times as many differentiating circuits and relay switches as the types of endoscopes in the video processor 24, and any endoscope is driven by a common video processor (driving pulse generating circuit). In addition, the light source connector 66
Since the variable voltage power supply circuit 76 is provided inside, the substrate bias voltage Vsub is adjusted for each endoscope (CCD 12). Therefore, even if there are variations in the thicknesses of the P layer and the N layer during manufacture of the CCD 12, the optimum DC substrate bias voltage is always applied to the CCD 12 and the CCD 12 is efficiently driven.

Next, a second embodiment of the electronic endoscope according to the present invention will be described. FIG. 2 is a block diagram of the essential parts of the second embodiment. Although not described in the first embodiment, if the length of the signal line changes, not only the waveform but also the amplitude is attenuated. Since the degree of this attenuation is greater for signals of high frequency, horizontal drive pulse, reset pulse, and vertical drive pulse are C
In order to apply to the CD 12, the output amplitude of the horizontal drive circuits 40 and 42 and the reset drive circuit 44 must be made larger than that of the vertical drive circuit. Therefore, in the second embodiment, the selection voltage power supply circuits 80, 82, 84 provided in the video processor 24 with the power supply voltages VH ₁ , VH ₂ , VR supplied to the horizontal drive circuits 40, 42 and the reset drive circuit 44, respectively. Is generated from.

Each selection voltage power supply circuit 80, 82, 84 comprises a switching circuit 86, n resistors R ₁ , R ₂ , ..., R _n , and a variable voltage regulator 88. The switching circuit 86 switches _one of n (the number of endoscopes used) resistors R ₁ , R ₂ , ..., R _n according to switching signals X ₁ , X ₂ , and X ₃ supplied from the outside. It enables one and disables the others. Variable voltage regulator
The output voltage of 88 is determined by the resistance value of the enabled resistor. Therefore, the resistance value of the resistors R ₁ , R ₂ , ..., R _n is determined to a value according to the length of the endoscope used.

The switching signals X ₁ , X ₂ , X ₃ are generated as follows. Contact pins P ₁ , P ₂ , P in the processor connector 68
₃ , P _g are provided. The contact pins P ₁ , P ₂ , P ₃ are connected to the power source E via resistors R _p1 , R _p2 , R _p3 , respectively. The contact pin P _g is grounded. Contact pins P ₁ , P ₂ ,
Switching signals X ₁ , X ₂ , and X ₃ are generated from the connection points of P ₃ and resistors R _p1 , R _p2 , and R _p3 , respectively. The contact pins P ₁ , P ₂ , P ₃ in the processor connector 68 are opened or grounded (contact pin P _g depending on the type (length) of the endoscope).
It is connected to the. For example, the contact pins P ₁ , P ₂ , P
_When all ₃ are open, the switching signals X ₁ , X ₂ ,
All of X ₃ become the power supply level (high level). If it is grounded either contact pins _{P 1,} P 2, _{P 3,} the switching signal _X 1 corresponding to the contact pins _{P 1,} P 2, _{P 3} which is _grounded, X 2, _{X 3} is a ground level (Low level). Therefore, the switching signals X ₁ , X ₂ , and X ₃ can take a total of 2 ³ = 8 states. Therefore, a total of eight types of endoscopes can be supported. The other parts not shown are the same as in the first embodiment.

As described above, according to the second embodiment, it is possible to compensate not only the distortion of the waveform when transmitted through the signal line but also the attenuation of the amplitude.

The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the gist of the invention. For example,
The vertical drive pulse may be similarly compensated. Further, the light source device and the video processor may be integrated.

〔The invention's effect〕

As described above, according to the present invention, since the circuit for compensating the waveform distortion of the driving pulse due to the length of each endoscope is provided in the light source connector of the endoscope, the entire endoscope is provided in the video processor. Provided is an electronic endoscope apparatus capable of compensating for distortion of a drive pulse waveform with a simple configuration without providing a compensating circuit for a mirror.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an electronic endoscope apparatus according to the present invention, and FIG. 2 is a block diagram of the essential parts of a second embodiment of the electronic endoscope apparatus according to the present invention. The figure is a block diagram of a conventional electronic endoscope apparatus. 12 ... CCD 14 ... Light source device 24 ... Video processor 30 ... Display device 32 ... Drive pulse generation circuit 40, 42, 44, 46, 48 ... Drive circuit 66 ... Light source connector 68 ... Processor connector 70, 72, 74 ... Differentiation circuit 76 ... Variable voltage power supply circuit

Claims (4)

[Claims] 1. An endoscope having a solid-state imaging device at its tip, a light source device for generating illumination light for illuminating an observation site, and a light source device connector for connecting the endoscope and the light source device. For the light source device, by connecting a signal processing device that generates a drive pulse of the solid-state imaging device and processes a signal output from the solid-state imaging device, and the light source device connector and the signal processing device. A signal processing device connector that connects the endoscope and the signal processing device via a connector, and a waveform distortion that is provided in the light source device connector and is transmitted during transmission of the drive pulse to the solid-state imaging device. And a waveform compensating means for compensating the same in advance. 2. The variable voltage power supply, which is provided in the connector for the light source device and generates a DC voltage applied to the solid-state image pickup device, according to claim 1. Electronic endoscope device. 3. A means for amplifying the amplitude of the drive pulse is provided in the connector for the light source device and amplifies the amplitude of the drive pulse so as to previously compensate for the attenuation of the amplitude during the transmission of the drive pulse to the solid-state imaging device. The electronic endoscope apparatus according to claim 1 or 2, wherein: 4. The electronic endoscope apparatus according to claim 1, wherein the driving pulse is a horizontal driving pulse and a reset pulse.