JP2008292730A - Endoscope device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endoscope device wherein a signal line outputting an image signal from an imaging means satisfies a safety standard as an explosion-proof structure, allowing securing of signal quality of the image signal regardless of a frequency characteristic of the image signal. <P>SOLUTION: This endoscope device 1 has: an insertion part inserted into a test object; the imaging means 9 provided on a tip side of the insertion part, imaging the test object to output the image signal; an image signal processing means 11 provided on a base end side to the imaging means 9, signal-processing the image signal input through the signal lines 20a, 20b; and an imaging output barrier part 22 provided between the imaging means 9 and the image signal processing means 11, restricting electric energy to make the imaging means 9 side the explosion-proof structure. The imaging output barrier part 22 has a plurality of signal input side barrier circuits 25, 26 each transmitting a prescribed frequency area of the image signal as a transmission frequency component with a low attenuation amount compared to the other frequency area as the signal input side barrier circuits 25, 26 having the transmission frequency components different from each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an endoscope apparatus for performing an internal inspection or the like using a plant or building maintenance, an apparatus or boiler in which flammable gas or dust is present as an object, and in particular, a place with a high possibility of explosion. The present invention relates to an endoscope apparatus that can be used in the field.

  Conventionally, by inserting an elongated insertion portion into a body cavity, it is possible to observe internal organs of the body cavity and perform various therapeutic treatments using a treatment instrument inserted into a treatment instrument channel as necessary. Endoscopic devices are widely used. Also in the industrial field, industrial endoscope apparatuses are widely used for observing and inspecting internal scratches and corrosion of boilers, turbines, engines, chemical plants, and the like. In the internal speculum apparatus used as described above, an electronic device in which an imaging element such as a CCD that photoelectrically converts an optical image into an image signal as an imaging means is disposed at the distal end of an insertion portion that is inserted into a subject. There is an endoscope apparatus (hereinafter abbreviated as an endoscope apparatus).

  More specifically, such an internal speculum device includes, for example, the above-described imaging element such as a CCD that images an observation site, a light source unit that illuminates the observation site, and a control unit having a power source and a signal processing unit. Yes. The control unit, the image sensor and the light source unit are connected by a cable composed of a plurality of electric wires, and the power supply from the control unit to the image sensor and the light source unit and the image sensor and the light source unit are controlled via the cable. Transmission and reception of control signals and image signals from the image sensor and the light source unit are performed. Then, an observation image of the observation site illuminated by the illumination light supplied from the light source unit is formed on the imaging surface of the imaging element, and an image signal of the observation image photoelectrically converted by the imaging element is converted into a signal processing unit of the control unit To communicate. Then, it is possible to perform observation by generating a video signal in the signal processing unit and displaying an observation image on the monitor screen.

By the way, some endoscope apparatuses used in the industrial field are used in dangerous places (hereinafter referred to as dangerous places) such as explosive atmospheres such as pipes and gas tanks of chemical plants. As such an endoscope apparatus, an endoscope apparatus in which a barrier circuit that restricts energy so as to satisfy safety standard conditions is interposed between a power source of a control unit, an imaging element, and a light source unit. Yes (for example, see Patent Document 1).
In recent years, the safety standard conditions required for explosion-proof structures must satisfy at least the safety standard conditions for intrinsically safe explosions.

Here, the intrinsically safe explosion-proof among the explosion-proof will be described below.
Intrinsically safe explosion-proof is standardized by IEC (International Electrotechnical Commission), ATEX (Europe), FM (USA), CSA (Canada), TIIS (Japan), etc. and certified as an explosion-proof device by a certification body. In this specification, description will be made based on IEC gas vapor explosion-proof standard IEC 60079 and dust explosion-proof IEC 61241. However, it is needless to say that the portions that substantially correspond to the standards of other countries can be applied to the standards of other countries and do not exclude other standards.

  Considering the mechanism of explosions in hazardous areas, explosions generally exceed the ignition temperature of the mixed gas or dust by raising the temperature of the ignition source in an environment where a mixture of flammable gas or dust and oxygen is present. By triggering. For example, in a gasoline tank, a plant, and an engine, fuel is gasified or dusted to become flammable, and oxygen is present in the surroundings, and is in a flammable mixed state.

  Under such circumstances, when an ignition source exists as described above, there is a risk of causing an explosion depending on the temperature of the ignition source. Conversely, there are three explosion elements: combustible gas or dust, oxygen, and ignition source. If one of these three is missing, no explosion occurs. Of these, flammable gas or dust and oxygen are environmentally present, and intrinsically safe explosion-proof is assured by basically removing the energy application element from the ignition source.

  In the IEC, Zone 0, Zone 1 and Zone 2 are defined as the places of use for safety explosion-proof products according to the level of danger. That is, Zone 0 has the highest risk, Zone 1 has the next highest risk, and Zone 2 has the next highest risk. The hazardous area is designated as Hazardous Area, and the non-hazardous area is designated as Non-Hazardous Area.

As for the device structure, ia device, ib device, and Type-n are defined. That is, the ia device has the highest reliability against explosion, and the ib device has the next highest reliability. Here, the ia device can be used in Zone0 and Zone1, and the ib device can be used only in Zone1. A device that can be used in Zone 0 or Zone 1 is called an intrinsically safe explosion-proof device. Note that the Type-n device can be used in Zone2.
JP 2001-75020 A

However, in the endoscope apparatus of Patent Document 1, a barrier circuit is not provided in the output line from the image sensor, and at least the safety standard condition as an explosion-proof structure is not satisfied. In order to satisfy the condition, it is necessary to provide a barrier circuit on the output line from the image sensor. On the other hand, in the endoscope apparatus shown in Patent Document 1, the imaging element is a C-MOS image sensor. However, in the endoscope apparatus, a CCD image sensor is also widely used as the imaging element. Here, when a CCD image sensor is selected as the image pickup element and a barrier circuit is provided on the output line, the CCD output signal is an analog signal, so that a barrier circuit is provided with a digital output C-MOS image sensor. It is very difficult. In particular, in CCD image sensors, attention must be paid to the frequency characteristics of the barrier circuit, and there is a problem that the signal quality deteriorates unless a barrier circuit having a wide frequency characteristic and a wide frequency characteristic that transmits both DC and AC is provided. was there.

  The present invention has been made in view of the above-described circumstances, and the signal line for outputting the image signal from the imaging means satisfies the safety standard as an explosion-proof structure, and the image signal regardless of the frequency characteristics of the image signal. It is an object of the present invention to provide an endoscope apparatus capable of ensuring the signal quality.

In order to solve the above problems, the present invention proposes the following means.
The present invention provides an insertion portion to be inserted into a subject, an imaging means that is provided at the distal end side of the insertion portion and that images the subject and outputs an image signal, and is provided closer to the proximal end than the imaging means. The image signal processing means for processing the image signal inputted through the signal line, and provided between the imaging means and the image signal processing means, restricts the electric energy and controls the imaging means side. An imaging output barrier unit having an explosion-proof structure, and the imaging output barrier unit transmits the image signal with a predetermined frequency region as a transmission frequency component and a low attenuation compared to other frequency regions. A plurality of input-side barrier circuits have different transmission frequency components from each other.

  According to the endoscope apparatus according to the present invention, the image signal that is captured and output by the imaging unit is input to the image signal processing unit via the signal line and subjected to signal processing. At this time, an imaging output barrier unit is provided between the imaging unit and the image signal processing unit, so that the imaging unit and the signal line can have an explosion-proof structure. In addition, since the imaging output barrier section includes a plurality of signal input side barrier circuits having different transmission frequency components, one signal input side barrier is effectively restricted by each signal input side barrier circuit. The frequency region of the image signal attenuated by the circuit can be complemented by the image signal transmitted through the other signal input side barrier circuit, and the signal quality as a whole can be ensured. The explosion-proof structure mentioned here includes all structures where the electric energy supplied is limited so that it does not become an energy application element for the explosive atmosphere. The type and concentration of the explosive atmosphere, the explosive atmosphere However, it is not limited by the required safety factor.

  Further, in the above endoscope apparatus, the imaging output barrier unit is a first barrier circuit that transmits a low frequency component as the transmission frequency component, and a high frequency component as the transmission frequency component as the signal input side barrier circuit. It is more preferable to have a second barrier circuit that transmits light.

  According to the endoscope apparatus according to the present invention, in the imaging output barrier unit, the low frequency component of the image signal is transmitted with a low attenuation amount by the first barrier circuit, and the image signal is transmitted by the second barrier circuit. By transmitting the high-frequency component with a low attenuation, the attenuated components can be complemented to ensure signal quality as a whole.

  In the above endoscope apparatus, the plurality of signal input side barrier circuits are connected to each other on the image signal processing means side, synthesize outputs, and input the image signals to the image signal processing means. Is more preferable.

  According to the endoscope apparatus according to the present invention, by synthesizing image signals transmitted through a plurality of signal input side barrier circuits, the attenuated components can be complemented with each other and output as one image signal.

  In the endoscope apparatus, the image signal is provided between the imaging unit and the imaging output barrier unit, and the image signal is distributed and input to the plurality of signal input side barrier circuits of the imaging output barrier unit. It is more preferable to provide an image signal distribution circuit that performs this.

  According to the endoscope apparatus according to the present invention, an image signal can be suitably input to each signal input side barrier circuit of the imaging output barrier section by the image signal distribution circuit.

  In the above endoscope apparatus, the imaging output barrier unit is provided in a power supply line that supplies power from the image signal processing unit side to the imaging unit side, and limits a power supply side barrier circuit. It is said that it is more preferable to have.

  According to the endoscope apparatus according to the present invention, the electric energy is also limited in the power supply line that supplies power from the image signal processing unit to each component on the imaging unit side by the power supply side barrier circuit of the imaging output barrier unit. Can do.

  In the above endoscope apparatus, the first barrier circuit includes a resistor inserted in the signal line and at least one Zener diode connected between the signal line and a ground point. Is more preferable.

  According to the endoscope apparatus according to the present invention, the Zener diode can effectively limit the voltage applied to the imaging means side while transmitting the low frequency component of the image signal with a low attenuation amount, The current that flows into the imaging means can be effectively limited by the resistor.

  In the endoscope apparatus described above, the first barrier circuit preferably includes two or more zener diodes, and the imaging means side is preferably an ib device based on an explosion-proof regulation. Yes.

  According to the endoscope apparatus according to the present invention, by having two or more Zener diodes, an explosion-proof structure can be guaranteed even if one of them is broken, and it can be handled as an ib device. .

  In the endoscope apparatus described above, the first barrier circuit preferably includes three or more zener diodes, and the imaging means side is preferably an ia device based on an explosion-proof regulation. Yes.

  According to the endoscope apparatus according to the present invention, by having three or more zener diodes, an explosion-proof structure can be ensured even if two are damaged, and it can be handled as an ia device. .

  In the endoscope apparatus described above, it is more preferable that the second barrier circuit has at least one capacitor interposed in the signal line.

  According to the endoscope apparatus according to the present invention, it is possible to effectively limit the electric energy applied to the imaging means side while allowing the high-frequency component of the image signal to pass through with a low attenuation amount by the capacitor.

  In the endoscope apparatus described above, the second barrier circuit preferably includes two or more capacitors, and the imaging means side is preferably an ib device based on explosion-proof regulations. .

  According to the endoscope apparatus according to the present invention, by having two or more capacitors, the explosion-proof structure can be guaranteed even if one of the capacitors is broken, and it can be handled as an ib device.

  In the endoscope apparatus described above, the second barrier circuit preferably includes three or more capacitors, and the imaging means side is preferably an ia device based on explosion-proof regulations. .

  According to the endoscope apparatus according to the present invention, by having three or more capacitors, an explosion-proof structure can be guaranteed even if two capacitors are damaged, and it can be handled as an ia device.

  In the above endoscope apparatus, it is more preferable that the power supply side barrier circuit has at least one Zener diode connected between the power supply line and a ground point.

  According to the endoscope apparatus according to the present invention, the electric energy applied to the imaging means side can be effectively limited by the Zener diode.

  In the endoscope apparatus described above, the power supply-side barrier circuit preferably includes two or more zener diodes, and the imaging means side is preferably an ib device based on explosion-proof regulations. Yes.

  According to the endoscope apparatus according to the present invention, by having two or more Zener diodes, an explosion-proof structure can be guaranteed even if one of them is broken, and it can be handled as an ib device. .

  In the endoscope apparatus described above, the power supply-side barrier circuit preferably includes three or more zener diodes, and the imaging means side is preferably an ia device based on explosion-proof regulations. Yes.

  According to the endoscope apparatus according to the present invention, by having three or more zener diodes, an explosion-proof structure can be ensured even if two are damaged, and it can be handled as an ia device. .

  The endoscope apparatus may further include a preamplifier that amplifies the attenuation of the image signal by transmitting the image signal between the imaging unit and the image signal processing unit through the signal line. It is preferred.

  According to the endoscope apparatus according to the present invention, it is possible to increase the output of the image signal attenuated by transmitting the signal line output from the imaging unit by amplifying the image signal with the preamplifier, and the signal quality. Can be made more suitable.

  In the endoscope apparatus described above, it is more preferable that the preamplifier is provided on the imaging unit side than the imaging output barrier unit.

  According to the endoscope apparatus according to the present invention, the preamplifier is provided on the imaging unit side, and the image signal is deteriorated in the imaging output barrier unit by inputting the amplified image signal to the imaging output barrier unit. This can be prevented and the signal quality can be made more suitable.

  In the endoscope apparatus described above, it is more preferable that the preamplifier amplifies the image signal by including an increase / decrease by the imaging output barrier unit in an attenuation by the signal line.

  According to the endoscope apparatus according to the present invention, the signal quality of the image signal can be further improved because the print amplifier amplifies the image signal including the increase / decrease by the imaging output barrier unit.

  According to the endoscope apparatus of the present invention, since the imaging output barrier section has a plurality of signal input side barrier circuits, the imaging means and the signal line for transmitting the image signal satisfy safety standards as an explosion-proof structure. At the same time, it is possible to ensure the signal quality of the image signal regardless of the frequency characteristics of the image signal.

(First embodiment)
A first embodiment according to the present invention will be described with reference to FIGS.
An endoscope apparatus 1 according to the present embodiment is an elongated insertion portion 2 that is inserted into a subject, a main body portion 3 provided on the proximal end side of the insertion portion 2, and a display such as a liquid crystal display (LCD). And a remote controller 5 connected to the main body unit 3 for performing various operations. Further, the recording medium 6 can be attached to and detached from the main body 3, and it is possible to record a still image or a moving image by recording a video signal generated by an image signal processing unit 11 described later as data. ing.

  At the distal end portion of the insertion portion 2, an LED 7 which is an illuminating means for illuminating the distal end side and an imaging means 9 for capturing an image of the subject on the distal end side are provided. The imaging means 9 includes an objective lens 9a and a CCD (Charge Coupled Device) 9b that is an imaging device that photoelectrically converts an observation image formed at the imaging position of the objective lens 9a into an image signal. The main body 3 includes an imaging drive unit 10 that drives the CCD 9b, an image signal processing unit 11 that processes an image signal output from the CCD 9b, an illumination drive unit 12 that drives the LED 7, and an image signal processing unit 11. And a system control unit 13 for controlling the illumination drive unit 12 is incorporated.

  The imaging drive unit 10 and the image signal processing means 11 are connected to each other and are connected to the CCD 9b by composite coaxial cables disposed in the insertion unit 2, respectively. That is, the CCD 9 b performs photoelectric conversion at a timing based on the imaging drive signal output by the imaging drive unit 10, and the image signal photoelectrically converted by the CCD 9 b is output to the image signal processing unit 11. The image signal processing means 11 communicates with the system control unit 13, and the system control unit 13 receives inputs from the remote controller 5 (Zoom signal, Freeze signal, contrast correction setting, gamma correction setting, Brightness setting, etc.) A corresponding signal is input to the image signal processing means 11, and the image signal processing means 11 performs each process based on this input signal. The image signal processing means 11 processes the input image signal and records it as a video signal in the video recording unit 14 built in the main body unit 3, and the video recording unit 14 is input to the system control unit 13. Based on the input signal from the remote controller 5, the video data is displayed on the display unit 4 and recorded on the recording medium 6.

  Moreover, the illumination drive part 12 is similarly connected with LED7 with the cable. That is, the system control unit 13 inputs an illumination lighting signal to the illumination driving unit 12 based on an input of a switch of the remote controller 5 or the like. The illumination drive unit 12 outputs an illumination drive signal to the LED 7 based on the input illumination lighting signal, and thereby the lighting and extinguishing of the LED 7 are controlled.

  Here, an imaging drive barrier means 15 for limiting the electrical energy from the imaging drive unit 10 to the CCD 9b is interposed between the imaging drive unit 10 and the CCD 9b. Further, an imaging output barrier means 16 for limiting the electric energy from the image signal processing means 11 to the CCD 9b is interposed between the image signal processing means 11 and the CCD 9b. Furthermore, an illumination drive barrier means 17 for limiting the electric energy from the illumination drive unit 12 to the LED 7 is interposed between the illumination drive unit 12 and the LED 7. The imaging drive barrier unit 15, the imaging output barrier unit 16, and the illumination drive barrier unit 17 are energy limiting circuits that satisfy the safety standard conditions of intrinsically safe explosion-proof, and are built in the main body 3. That is, the imaging drive barrier means 15, the imaging output barrier means 16, and the illumination drive barrier means 17 make the insertion portion 2 located on the tip side from these as an explosion-proof device and fail in the main body portion 3 on the non-explosion-proof device side. Even if excessive energy is generated due to the above, only predetermined energy limited by the energy limiting circuit is applied to the insertion portion 2 side which is an explosion-proof device. Details of the imaging output barrier means 16 will be described below.

  FIG. 2 is a block diagram showing details of the imaging output barrier means 16 in the endoscope apparatus 1. As shown in FIG. 2, the imaging output barrier unit 16 includes power between the signal lines 20 a and 20 b that transmit the image signal output from the CCD 9 b to the image signal processing unit 11 and the power output from the image signal processing unit 11. Between the power supply lines 21a and 21b for supplying power to the CCD 9b, an imaging output barrier section 22 for limiting electrical energy from the image signal processing means 11 to the CCD 9b, a preamplifier 23 for amplifying an image signal output from the CCD 9b, and a preamplifier And an image signal distribution circuit 24 that distributes the image signal amplified at 23 and inputs the image signal to each circuit of the imaging output barrier unit 22.

  The imaging output barrier unit 22 includes a first barrier circuit 25 and a second barrier circuit 26 as a signal input-side barrier circuit that is inserted between the signal lines 20a and 20b to limit electric energy, and includes a power source. And a power supply-side barrier circuit 27 that is inserted between the lines 21a and 21b to limit electric energy. That is, the power output from the image signal processing means 11 is output to the CCD 9 b side in a form of energy limitation by the power supply side barrier circuit 27 and supplied to the preamplifier 23 and the image signal distribution circuit 24. The image signal output from the CCD 9b is input to the preamplifier 23 via the signal line 20a and amplified. Here, the preamplifier 23 takes into account the amount that is attenuated by transmission over a long distance in the insertion section 2 by the signal line 20a, and the amount that is increased or decreased by the first barrier circuit 25 and the second barrier circuit 26 that are input thereafter. Thus, the image signal is set to be amplified. The image signal amplified by the preamplifier 23 is distributed by the image signal distribution circuit 24 and input to the first barrier circuit 25 and the second barrier circuit 26 of the imaging output barrier unit 22. Here, as will be described later, the image signal distribution circuit 24 has a circuit configuration for inputting signals in an optimum signal form for each of the first barrier circuit 25 and the second barrier circuit 26.

  The first barrier circuit 25 has a circuit configuration that limits electric energy and transmits a low-frequency component with a low attenuation with respect to a high-frequency component in an input image signal, and the high-frequency component is removed. Is output as a signal. The second barrier circuit 26 limits electric energy and transmits a high-frequency component removed by the first barrier circuit 25 with a low attenuation with respect to a low-frequency component in the input image signal. The signal is output as a signal from which low-frequency components have been removed. The first barrier circuit 25 and the second barrier circuit 26 are connected on the image signal processing means 11 side, whereby the image signals output from the first barrier circuit 25 and the second barrier circuit 26, respectively. Are combined and input to the image signal processing means 11.

  Here, FIG. 3A shows the relationship between the frequency and the attenuation amount for the image signals transmitted through the first barrier circuit 25 and the second barrier circuit 26, respectively. FIG. 3B shows the relationship between the frequency and the attenuation amount for the image signal obtained by synthesizing the signals output from the first barrier circuit 25 and the second barrier circuit 26. As shown in FIG. 3A, the image signal S1 output from the first barrier circuit 25 is hardly attenuated in the low frequency region, but the attenuation amount increases as it goes to the high frequency region. The amount of attenuation becomes extremely large from a predetermined frequency determined by the configuration. Further, most of the image signal S2 output from the second barrier circuit 26 is attenuated in the low frequency region, but the attenuation amount is extremely small from a predetermined frequency determined by the circuit configuration. In the high frequency region, it is hardly attenuated. And as shown in FIG.3 (b), it can synthesize | combine and can output as an image signal S3 substantially equal to the input image signal as a whole. Here, the synthesized and output image signal S3 has a waveform slightly increased or decreased with respect to the frequency. Since it is difficult to completely equalize the increase / decrease amount, the average value S4 in which the ratio of the amplification component and the attenuation component substantially match is considered as the increase / decrease amount of the imaging output barrier unit 22 as described above. The preamplifier 23 considers and amplifies the image signal.

  As described above, the energy of the signal lines 20a and 20b is restricted between the CCD 9b and the image signal processing means 11 by the first barrier circuit 25 and the second barrier circuit 26 which are signal input side barrier circuits. At the same time, the power supply side barrier circuit 27 limits the energy of the power supply lines 21a and 21b so that the CCD 9b side, that is, the insertion portion 2 side of the imaging output barrier unit 22 can be an explosion-proof device. In order to make the insertion portion 2 side an explosion-proof device, it is necessary to keep a creepage / space distance by a predetermined distance with respect to a circuit built in the insertion portion 2 side.

  Next, details of a circuit for realizing the above configuration will be described with reference to FIG. As shown in FIG. 4, the preamplifier 23 is a grounded-base amplifier formed by resistors 23a, 23b, 23c, 23d, and 23e, and a transistor 23f. That is, the image signal input to the preamplifier 23 is input to the image signal distribution circuit 24 after being amplified by the amplification factor determined by the resistors 23a and 23d. The resistance values of the resistors 23a and 23d are the signals. This is determined by the attenuation of the line 20a and the increase / decrease of the first barrier circuit 25 and the second barrier circuit 26. Here, the operation of the common base amplifier of the preamplifier 23 will be specifically described. The base potential of the transistor 23f is determined by the resistors 23d and 23e, and the emitter potential of the transistor 23f is determined by having a potential difference corresponding to the base-emitter voltage of the transistor 23f with respect to the base potential. The collector current of the transistor 23f is determined by the emitter potential and the resistance value of the resistor 23c, and the frequency characteristics of the grounded base amplifier are determined by the collector current. Since the image signal output from the CCD 9b has a very high frequency, it is necessary to sufficiently consider the frequency characteristics.

  The image signal distribution circuit 24 directly inputs the image signal input from the preamplifier 23 to the second barrier circuit 26 of the imaging output barrier unit 22 without passing through a resistor or the like. The first barrier circuit 25 is inputted through an emitter follower circuit formed by the transistors 24a and 24b and the transistor 24c. Here, as shown below, the first barrier circuit 25 has a lower impedance than the second barrier circuit 26. For this reason, the impedance is converted through the emitter follower circuit to reduce the load.

  In the imaging output barrier unit 22, the first barrier circuit 25 includes a resistor 25a interposed between the signal lines 20a and 20b, and Zener diodes 25b and 25c provided between the signal lines 20a and 20b and the grounding point. 25d and a fuse 25e inserted in the signal lines 20a and 20b. Here, since the Zener diodes 25b, 25c, and 25d have a capacitance component, a low-pass filter is formed together with the resistor 25a. For this reason, as described above, the high frequency component is attenuated and only the low frequency component passes with a low attenuation. Here, the first barrier circuit 25 is an energy limiting circuit necessary for an intrinsically safe explosion-proof ia device. First, the voltage applied to the explosion-proof device side (CCD 9b side) is limited by the combination of the fuse 25e and the Zener diodes 25b, 25c, and 25d. The fuse 25e is necessary to guarantee the rated power of the Zener diodes 25b, 25c, and 25d. In addition, the current flowing into the explosion-proof device side (CCD 9b side) is limited by the resistor 25a. In this way, it is possible to limit the energy applied to the explosion-proof device side (CCD 9b side) by limiting the voltage and current respectively. Further, three Zener diodes are provided as described above, and are configured to be able to guarantee an explosion-proof structure even if two are damaged, that is, correspond to ia devices.

The second barrier circuit 26 is formed by capacitors 26a, 26b, and 26c. Here, the frequency components that pass through the capacitors differ depending on the capacitance, and components below a predetermined frequency determined by the capacitance do not pass, that is, a high-pass filter is formed.
For this reason, as described above, the low frequency component is attenuated, and only the high frequency component passes with a low attenuation. Here, the second barrier circuit 26 is an energy limiting circuit necessary for an intrinsically safe explosion-proof ia device. That is, three are provided as described above, and an explosion-proof structure can be guaranteed even if two are damaged, and is compatible with ia devices. In order to make the above circuit effective as an energy limiting circuit, it is necessary that the capacitors 26a, 26b, and 26c have a withstand voltage with a sufficient margin with respect to a voltage that can be considered due to a normal failure.

  Here, the output of the first barrier circuit 25 and the output of the second barrier circuit 26 need to be combined and averaged as shown in the example of FIG. Capacitance components of the Zener diode of the first barrier circuit 25 and the capacitor of the second barrier circuit 26 are determined so as to complement each other. Then, the signals output from the first barrier circuit 25 and the second barrier circuit 26 are combined and input to the transistor 22a. The transistor 22a and the resistor 22b form an emitter follower circuit and are input to the image signal processing means 11 with low impedance.

  The power supplied from the image signal processing means 11 is connected to the collector as the power source of the transistor 22a in the imaging output barrier unit 22, and is also connected to the power supply barrier circuit 27 via the power source line 21a and via the power source line 21b. The image signal distribution circuit 24 and the preamplifier 23 are connected as power sources. The power supply side barrier circuit 27 includes a fuse 27a inserted in the power supply lines 21a and 21b, Zener diodes 27b, 27c and 27d connected between the power supply lines 21a and 21b and the ground point, and the power supply lines 21a, 21b, And a resistor 27e inserted in 21b. Here, the power supply side barrier circuit 27 is an energy limiting circuit necessary for an intrinsically safe explosion-proof ia device. First, the voltage applied to the explosion-proof device side (CCD 9b side) is limited by the combination of the fuse 27a and the Zener diodes 27b, 27c, and 27d. The fuse 27a is necessary to guarantee the rated power of the Zener diodes 27b, 27c, and 27d. In addition, the current flowing into the explosion-proof device side (CCD 9b side) is limited by the resistor 27e. In this way, it is possible to limit the energy applied to the explosion-proof device side (CCD 9b side) by limiting the voltage and current, respectively, and output to the image signal distribution circuit 24 and the preamplifier 23 after the energy limitation. Has been used as each power supply. Further, three Zener diodes are provided as described above, and are configured to be able to guarantee an explosion-proof structure even if two are damaged, that is, correspond to ia devices.

  As described above, in the endoscope apparatus 1 of the present embodiment, the imaging output barrier unit 22 is provided between the imaging unit 9 and the image signal processing unit 11 that processes the image signal from the imaging unit 9. Thus, the output line of the image pickup means 9 has an explosion-proof structure, and in particular, by satisfying the above-mentioned circuit, it is possible to satisfy the safety standard condition of intrinsically safe explosion-proofing for ia equipment. Then, the imaging output barrier unit 22 effectively limits the electric energy by the first barrier circuit 25 and the second barrier circuit 26, and reduces the frequency region of the image signal attenuated by one barrier circuit to the other barrier circuit. It can be supplemented by an image signal that passes through the circuit. For this reason, even if a CCD 9b having a wide range of frequency characteristics is selected as the imaging means 9, signal quality as a whole can be ensured regardless of the frequency characteristics. Moreover, in the endoscope apparatus 1 of this embodiment, since the image signal is amplified by the preamplifier 23, the output of the image signal attenuated by transmitting the signal line 21a as described above can be increased. The signal quality can be made more suitable. In the present embodiment, the preamplifier 23 is provided on the imaging unit 9 side with respect to the imaging output barrier unit 22. However, the present invention is not limited to this, and the preamplifier 23 may be provided on the image signal processing unit 11 side. However, by providing the preamplifier 23 on the imaging means 9 side, the amplified image signal can be input to the first barrier circuit 25 having a low impedance and a heavy load, preventing the image signal from being deteriorated and improving the signal quality. It can be made suitable.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 5 shows a second embodiment of the present invention. In this embodiment, members that are the same as those used in the above-described embodiment are assigned the same reference numerals, and descriptions thereof are omitted.

  As shown in FIG. 5, in the endoscope apparatus 30 of the present embodiment, an imaging output barrier unit 31 that restricts electric energy between the CCD 9b and the image signal processing unit 11 is inserted in the signal lines 20a and 20b. As a signal input side barrier circuit that restricts electrical energy, the first barrier circuit 32 and the second barrier circuit 33 are provided, and the power supply side barrier that is interposed in the power supply lines 21a and 21b to restrict electrical energy. Circuit 34.

  The first barrier circuit 32 is formed of a resistor 32a, Zener diodes 32b and 32c, and a fuse 32d. The resistor 32a and the Zener diodes 32b and 32c form a low-pass filter. Further, the voltage on the explosion-proof device side (CCD 9b side) is limited by the fuse 32d and the Zener diodes 32b and 32c, and the current is limited by the resistor 32a, thereby the energy applied to the explosion-proof device side (CCD 9b) side. Restricted. Further, two Zener diodes are provided as described above, and are configured to guarantee an explosion-proof structure even if one of them is broken, that is, corresponding to an ib device.

  The second barrier circuit 33 is formed of capacitors 33a and 33b to form a high-pass filter and limit energy applied to the explosion-proof device side (CCD 9b) side. In addition, two capacitors are provided as described above, and the explosion-proof structure can be guaranteed even if one capacitor is broken, that is, it corresponds to an ib device.

  The power supply side barrier circuit 34 includes a fuse 34a, Zener diodes 34b and 34c, resistors 34d, 34e, 34f, and 34g, and FETs (Field Effect Transistors) 34h, 34i, 34j, and 34k. . Here, the power supply side barrier circuit 34 is an energy limiting circuit necessary for an intrinsically safe explosion-proof ib device. First, the voltage applied to the explosion-proof device side (CCD 9b side) is limited by the combination of the fuse 34a and the Zener diodes 34b and 34c. The fuse 34a is necessary to guarantee the rated power of the Zener diodes 34b and 34c. In addition, the current flowing into the explosion-proof device side (CCD 9b side) is limited by a current limiting circuit formed by the resistors 34d, 34e, 34f, 34g and the FETs 34h, 34i, 34j, 34k. Details of the operation of the current limiting circuit will be described below.

  That is, when the current flowing into the resistor 34d increases, the gate-source voltage of the FET 34i increases, and when the voltage exceeds a predetermined vth, the FET 34i is turned on. Immediately after the FET 34i is turned on, the voltage between the gate and the source of the FET 34h is reduced to be lower than a predetermined vth, and the FET 34h is turned off. Furthermore, immediately after the FET 34h is turned off, the current flowing through the resistor 34d decreases. As a result, the gate-source voltage of the FET 34i is lowered and the FET 34i is turned off. By repeating the above phenomenon, the current is finally limited by the current value determined by (vth of FET 34i) / (resistance value of resistor 34d). Note that the current limiting circuit formed by the resistors 34f and 34g and the FETs 34j and 34k also operates in the same manner to limit the current. As described above, the energy applied to the explosion-proof device is limited by limiting the voltage and current. And in the electric power supply side barrier circuit of this embodiment, since the electric current is restricted using FET, the electric current interruption characteristic becomes steep and a favorable characteristic can be obtained.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 6 shows a third embodiment of the present invention. In this embodiment, members that are the same as those used in the above-described embodiment are assigned the same reference numerals, and descriptions thereof are omitted.

  As shown in FIG. 6, in the endoscope apparatus 40 of the present embodiment, an imaging output barrier unit 41 that limits electrical energy between the CCD 9b and the image signal processing unit 11 is a first signal input side barrier circuit. And a second barrier circuit 33, and a power supply-side barrier circuit 42 that is interposed between the power supply lines 21a and 21b to limit electric energy.

  The power supply side barrier circuit 42 is formed of a fuse 42a, Zener diodes 42b and 42c, resistors 42d, 42e, 42f, and 42g, and transistors 42h, 42i, 42j, and 42k. Here, the power supply side barrier circuit 42 is an energy limiting circuit necessary for an intrinsically safe explosion-proof ib device. First, the combination of the fuse 42a and the Zener diodes 42b and 42c limits the voltage applied to the explosion-proof device side (CCD 9b side). The fuse 42a is necessary to guarantee the rated power of the Zener diodes 42b and 42c. In addition, the current flowing into the explosion-proof device side (CCD 9b side) is limited by a current limiting circuit formed by the resistors 42d, 42e, 42f, and 42g and the transistors 42h, 42i, 42j, and 42k. Details of the operation of the current limiting circuit will be described below.

  That is, when the current flowing into the resistor 42d increases, the base-emitter voltage of the transistor 42h rises, and when the voltage exceeds a predetermined vbe, the transistor 42h is turned on. Since the base-emitter voltage when the transistor 42h is turned on is fixed at a predetermined vbe, the current flowing through the transistor 42i is a current value obtained by (vbe of the transistor 42h) / (resistance value of the resistor 42d). It becomes constant at. On the other hand, when the transistor 42h is turned on, a current limited by the resistor 42e flows. When the resistance value of the resistor 42e is sufficiently large with respect to the voltage limited by the Zener diodes 42b and 42c, the resistance value can be almost ignored. As a result, (vbe of the transistor 42h) / (resistance 42d resistance value), the current value is limited. Note that the current limiting circuit formed by the resistors 42f and 42g and the transistors 42j and 42k also operates in the same manner to limit the current. As described above, the energy applied to the explosion-proof device is limited by limiting the voltage and current. And in the electric power supply side barrier circuit of this embodiment, since the electric current is limited using a transistor, the current interruption characteristic becomes steep and good characteristics can be obtained.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  In each of the above embodiments, the first barrier circuit 25, the second barrier circuit 26, and the two barrier circuits are provided as the signal input side barrier circuit. However, the present invention is not limited to this. For example, a barrier circuit that transmits a low frequency, a barrier circuit that transmits a mid frequency, a barrier circuit that transmits a high frequency, and three barrier circuits may be provided. That is, a plurality of signal input barrier circuits are provided, and each signal input barrier circuit transmits an image signal with a low attenuation amount using a frequency region different from that of other signal input side barrier circuits as a transmission frequency component. The signal quality of the image signal can be ensured while the electric energy is limited by the signal input barrier circuit. In each of the above embodiments, the imaging drive barrier means 15, the imaging output barrier means 16, and the illumination drive barrier means 17 that are barrier means for limiting electric energy are provided in the main body 3. It is not limited. For example, in the case of an endoscope apparatus having a scope unit that has an operation part at the base end of the insertion part 2 and is detachable from the main body part 3, each barrier means is provided in the operation part provided in the insertion part 2. It may be built in. In this case, there is an advantage that a general-purpose product can be selected as the main body part to which the scope unit is attached and detached while effectively limiting the electric energy.

1 is a block diagram showing an overall configuration of an endoscope apparatus according to a first embodiment of the present invention. It is a block diagram which shows the detail of an imaging output barrier means in the endoscope apparatus of the 1st Embodiment of this invention. In the endoscope apparatus according to the first embodiment of the present invention, (a) the relationship between the frequency of the input image signal and the attenuation amount of the output image signal for the first barrier circuit and the second barrier circuit. (B) is a graph showing an example of the relationship between the frequency and the attenuation amount for the image signal output from the first barrier circuit and the second barrier circuit and synthesized. FIG. 3 is a circuit diagram showing details of an imaging output barrier means in the endoscope apparatus according to the first embodiment of the present invention. It is a circuit diagram which shows the detail of an imaging output barrier means in the endoscope apparatus of the 2nd Embodiment of this invention. FIG. 10 is a circuit diagram showing details of an imaging output barrier means in an endoscope apparatus according to a third embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 30, 40 Endoscope apparatus 2 Insertion part 9 Imaging means 11 Image signal processing means 20a, 20b Signal line 21a, 21b Power supply line 22, 31, 41 Imaging output barrier part 23 Preamplifier 24 Image signal distribution circuit 25, 32 1st Barrier circuit (signal input side barrier circuit)
25a Resistance 25b, 25c, 25d, 32b, 32c Zener diode 26, 33 Second barrier circuit (signal input side barrier circuit)
26a, 26b, 26c, 33a, 33b Capacitors 27, 34, 42 Power supply side barrier circuit 27b, 27c, 27d, 34b, 34c, 42b, 42c Zener diode

Claims (17)

An insertion part to be inserted into the subject;
An imaging means provided on the distal end side of the insertion portion for imaging the subject and outputting an image signal;
Image signal processing means for performing signal processing on the image signal input via a signal line provided on the base end side of the imaging means;
An imaging output barrier unit provided between the imaging unit and the image signal processing unit and having an explosion-proof structure on the imaging unit side by limiting electric energy;
The imaging output barrier unit includes a signal input-side barrier circuit that transmits a predetermined frequency region of the image signal as a transmission frequency component and transmits light with a low attenuation compared to other frequency regions. An endoscope apparatus having a plurality of different ones. The endoscope apparatus according to claim 1, wherein
The imaging output barrier unit is a first barrier circuit that transmits a low frequency component as the transmission frequency component as the signal input side barrier circuit;
An endoscope apparatus comprising: a second barrier circuit that transmits a high-frequency component as the transmission frequency component. The endoscope apparatus according to claim 1 or 2,
The endoscope apparatus characterized in that a plurality of the signal input side barrier circuits are connected to each other on the image signal processing means side, synthesize outputs, and input the image signals to the image signal processing means. The endoscope apparatus according to any one of claims 1 to 3,
An image signal distribution circuit is provided between the image pickup unit and the image pickup output barrier unit, and distributes and inputs the image signal to the plurality of signal input side barrier circuits of the image pickup output barrier unit. An endoscope apparatus. The endoscope apparatus according to any one of claims 1 to 4,
The endoscope, wherein the imaging output barrier section includes a power supply side barrier circuit that is provided in a power supply line that supplies power from the image signal processing means side to the imaging means side, and limits electric energy. apparatus. The endoscope apparatus according to claim 2, wherein
The first barrier circuit includes a resistor inserted in the signal line,
An endoscope apparatus comprising: at least one Zener diode connected between the signal line and a ground point. The endoscope apparatus according to claim 6, wherein
The endoscope apparatus according to claim 1, wherein the first barrier circuit includes two or more zener diodes, and the imaging means side is an ib device based on explosion-proof regulations. The endoscope apparatus according to claim 6, wherein
The first barrier circuit includes three or more zener diodes, and the imaging means side is an ia device based on explosion-proof regulations. The endoscope apparatus according to claim 2, wherein
The endoscope apparatus, wherein the second barrier circuit includes at least one capacitor interposed in the signal line. The endoscope apparatus according to claim 9, wherein
The endoscope apparatus according to claim 2, wherein the second barrier circuit includes two or more capacitors, and the imaging means side is an ib device based on explosion-proof regulations. The endoscope apparatus according to claim 9, wherein
The endoscope apparatus according to claim 2, wherein the second barrier circuit includes three or more capacitors, and the imaging means side is an ia device based on explosion-proof regulations. The endoscope apparatus according to claim 5, wherein
The endoscope apparatus, wherein the power supply side barrier circuit includes at least one Zener diode connected between the power supply line and a ground point. The endoscope apparatus according to claim 12, wherein
The endoscope apparatus characterized in that the power supply side barrier circuit has two or more zener diodes, and the imaging means side is an ib device based on explosion-proof regulations. The endoscope apparatus according to claim 12, wherein
The endoscope apparatus according to claim 1, wherein the power supply side barrier circuit has three or more zener diodes, and the imaging means side is an ia device based on explosion-proof regulations. The endoscope apparatus according to any one of claims 1 to 14,
An endoscope apparatus comprising: a preamplifier that amplifies an attenuation of the image signal by transmitting the image signal between the imaging unit and the image signal processing unit through the signal line. The endoscope apparatus according to claim 15,
The endoscope apparatus according to claim 1, wherein the preamplifier is provided closer to the imaging means than the imaging output barrier unit. The endoscope apparatus according to claim 15 or 16,
The endoscope apparatus amplifies the image signal by including an increase / decrease by the imaging output barrier unit in an attenuation by the signal line.

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