JP2012029719A - Electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic endoscope system suitable for detecting the disconnection of the GND wire arranged in an electronic scope.SOLUTION: The electronic endoscope system is configured to include the electronic scope having a solid-state imaging element provided to the leading end thereof, a signal processing means for performing the transmission and reception of a signal with respect to the solid-state imaging element connected to the base end of the electronic scope, a plurality of signal cables for connecting the solid-state imaging element and the signal processing means, a measuring means for measuring the synthetic resistance value of the GND wires of a plurality of the signal cables and a disconnection detection means for detecting the disconnection of the GND wires on the basis of the measuring result of the measuring means.

Description

  The present invention relates to an electronic endoscope system having an electronic scope that images a subject inside a tubular body, and more particularly to an electronic endoscope system that detects disconnection of a GND line wired inside the electronic scope.

  An electronic scope is generally known as a medical device used for diagnosing the inside of a body cavity of a patient. A solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) is incorporated at the tip of the electronic scope. The solid-state imaging device is electrically connected to a processor that processes imaging data via a signal line wired from the distal end portion to the proximal end portion of the electronic scope.

  Since the electronic scope reduces the burden on the patient when inserting the lumen, restrictions on the outer diameter are severe. For this reason, it is difficult to select a signal line having a large wire diameter as a signal line wired inside the electronic scope. On the other hand, stress is repeatedly applied to this type of signal line as the electronic scope bends. That is, since the signal line is repeatedly stressed despite its thin wire diameter, there is a risk of disconnection. When the signal line is disconnected, a functional failure such as failure to display images normally occurs. Therefore, Patent Documents 1 and 2 propose an electronic endoscope system having a configuration for detecting disconnection of a signal line.

  Specifically, the electronic endoscope system described in Patent Document 1 has a plurality of signal lines for various signals and is configured to detect disconnection of the signal lines. In such an electronic endoscope system, even if one signal line is disconnected, a signal can be transmitted through the remaining signal lines. Therefore, the occurrence of functional failure can be effectively avoided. The electronic endoscope system described in Patent Document 2 has a low-durability disconnection detection cable that is disconnected prior to a signal line, and is configured so that the disconnection of the signal line can be detected in advance.

JP 2006-26134 A Japanese Patent No. 3730731

  Incidentally, a GND line is also wired inside the electronic scope. As long as the signal line is normal even if the GND line is disconnected, the possibility of a functional failure is low. In addition, when the GND line has a plurality of coaxial lines, it is unlikely that a failure will occur even if some of the GND lines are disconnected. Therefore, in the technical field of the electronic endoscope system, it is considered that there is no practical advantage in detecting the disconnection of the GND line, and no specific means for detecting the disconnection of the GND line has been studied so far. It was.

  However, the present applicant has discovered that a malfunction such as a functional disorder occurs secondary to the disconnection of the GND line. Specifically, there is an example in which when the GND line is disconnected, the disconnected part is pierced into the insulating coating of the signal line, and the GND line and the signal line are short-circuited to cause a malfunction or the like.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic endoscope system suitable for detecting disconnection of a GND wire wired inside an electronic scope. is there.

  An electronic endoscope system according to an embodiment of the present invention that solves the above-described problem is a signal transmission between an electronic scope having a solid-state imaging device at a distal end and a solid-state imaging device connected to a proximal end of the electronic scope. Signal processing means for performing transmission / reception, a plurality of signal cables connecting the solid-state imaging device and the signal processing means, a measuring means for measuring the combined resistance value of the GND lines of the plurality of signal cables, and a measurement result by the measuring means And a disconnection detecting means for detecting disconnection of the GND line based on the above.

  According to the electronic endoscope system according to the present invention, since the disconnection of the GND line wired inside the electronic scope can be detected at an early stage, it is possible to prevent in advance problems that occur secondary to the disconnection of the GND line. Can do. In addition, since no separate wiring is required for detecting the disconnection of the GND line, an increase in the outer diameter of the electronic scope can be effectively avoided.

  The measuring means includes a constant current circuit for supplying a constant current to a load circuit composed of the resistances of the GND wires of a plurality of signal cables, and a voltage measuring means for measuring a voltage value applied to the load circuit, and the measured voltage value The combined resistance value may be calculated based on Alternatively, it has a constant voltage circuit that applies a constant voltage to the load circuit and a current measuring means that measures a current value applied to the load circuit, and calculates a combined resistance value based on the measured current value. Also good.

  The disconnection detecting means detects that the GND line is disconnected, for example, when the combined resistance value is outside a predetermined specified range.

  The electronic endoscope system according to the present invention may further include a message display unit that displays a predetermined warning message on the display screen when the disconnection of the GND line is detected by the disconnection detection unit.

  The signal cable that connects the solid-state imaging device and the signal processing means is, for example, a coaxial cable.

  ADVANTAGE OF THE INVENTION According to this invention, the electronic endoscope system suitable for detecting the disconnection of the GND wire wired inside the electronic scope is provided.

It is a block diagram which shows the structure of the electronic endoscope system of embodiment of this invention. It is a block diagram which shows the connection structure of the solid-state image sensor of embodiment of this invention, and an analog signal processing part. It is an equivalent circuit diagram when the switch SW1 is switched to the terminal S2. It is a figure which shows each process step which detects the disconnection of the GND line of a coaxial cable with a flowchart.

  Hereinafter, an electronic endoscope system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of an electronic endoscope system 1 according to the present embodiment. As shown in FIG. 1, the electronic endoscope system 1 includes an electronic scope 100 for photographing a subject. The proximal end of the electronic scope 100 is connected to the processor 200. The processor 200 is an apparatus that integrally includes a signal processing device that processes a signal from the electronic scope 100 and a light source device that illuminates a body cavity that does not reach natural light via the electronic scope 100. In another embodiment, the signal processing device and the light source device may be configured separately. In FIG. 1, for convenience of simplifying the drawing, illustration of some connections (for example, connection between the system controller 202 and the driver 216 and the like) is omitted.

  As illustrated in FIG. 1, the processor 200 includes a system controller 202 and a timing controller 204. The system controller 202 accesses the memory 112 of the electronic scope 100 and reads unique information of the electronic scope 100. The unique information of the electronic scope 100 includes, for example, the number of pixels and sensitivity of the solid-state image sensor 108, a compatible rate, a model number, and the like.

  The system controller 202 performs various calculations based on the unique information of the electronic scope 100 and generates a control signal. The timing controller 204 generates a clock pulse for adjusting the signal processing timing in accordance with a control signal from the system controller 202. The operation and timing of various circuits in the processor 200 are controlled by the generated clock pulse so that processing suitable for the electronic scope connected to the processor 200 is performed.

  The system controller 202 may be configured to have a table in which a model number of the electronic scope is associated with control information suitable for the electronic scope of the model number. In this case, the system controller 202 controls the timing controller 204 based on the control information in the correspondence table, and operates various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed. Control timing.

  The lamp 208 emits white light after being started by the lamp power igniter 206. As the lamp 208, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp is suitable. Illumination light emitted from the lamp 208 is collected by the condenser lens 210, is limited to an appropriate amount of light through the diaphragm 212, and enters an incident end of an LCB (light carrying bundle) 102.

  A motor 214 is mechanically connected to the diaphragm 212 via a transmission mechanism such as an arm or a gear (not shown). The motor 214 is a DC motor, for example, and is driven under the drive control of the driver 216. The diaphragm 212 is operated by the motor 214 to change the opening degree so that the image displayed on the monitor 300 has an appropriate brightness, and the amount of illumination light emitted from the lamp 208 is limited according to the opening degree. To do. The appropriate reference for the brightness of the image is changed according to the brightness adjustment operation of the front panel 218 by the operator. Note that the dimming circuit that controls the brightness by controlling the driver 216 is a well-known circuit and is omitted in this specification.

  Various forms of the configuration of the front panel 218 are assumed. As a specific configuration example of the front panel 218, a hardware key for each function mounted on the front surface of the processor 200, a touch panel GUI (Graphical User Interface), a combination of a hardware key and a GUI, and the like are assumed. .

  The illumination light incident on the incident end of the LCB 102 propagates by repeating total reflection in the LCB 102. The illumination light that has propagated through the LCB 102 is emitted from the exit end of the LCB 102 disposed at the tip of the electronic scope 100. The illumination light emitted from the exit end of the LCB 102 illuminates the subject via the light distribution lens 104. The reflected light from the subject forms an optical image at each pixel on the light receiving surface of the solid-state image sensor 108 via the objective lens 106.

  The solid-state image sensor 108 is, for example, a single-plate color CCD image sensor having a Bayer pixel arrangement. In another embodiment, the solid-state image sensor 108 may be a CMOS image sensor.

FIG. 2 is a block diagram illustrating a connection configuration between the solid-state imaging device 108 and the analog signal processing unit 220. The timing controller 204 supplies clock pulses to the drive circuit 220a in accordance with timing control by the system controller 202. The drive circuit 220a drives and controls the solid-state imaging device 108 at a timing synchronized with the frame rate of the video processed on the processor 200 side in accordance with the clock pulse. A plurality of signal lines are required to drive the solid-state image sensor 108. Therefore, the drive circuit 220a and the solid-state imaging device 108 are connected by a plurality of coaxial cables CC _A , CC ₂ ,..., CC _n that transmit various drive control signals, as shown in FIG.

The solid-state image sensor 108 accumulates an optical image formed by each pixel on the light receiving surface as a charge corresponding to the amount of light, and converts it into an image signal corresponding to each color of R, G, and B. As shown in FIG. 2, the converted image signal is amplified by the preamplifier 110, transmitted by the coaxial cable CC ₁ , and input to the analog processing circuit 220 b of the analog signal processing unit 220.

The imaging signal is input to the pre-stage signal processing unit 222 after AD conversion by the analog processing circuit 220b. In the pre-stage signal processing unit 222, the image signal is subjected to predetermined signal processing such as clamping, knee, γ correction, interpolation processing, AGC (Auto Gain Control), and the like, and then a frame for each color of the image memory 224 for each RGB color signal. Buffered in memory in frames. The buffered imaging signals of each color are swept from each frame memory at a timing controlled by the timing controller 204 and input to the subsequent signal processing unit 226. An imaging signal of each color is received by an NTSC (National Television System) by a subsequent signal processing unit 226.
It is converted into a video signal that conforms to a predetermined standard such as Committee) or PAL (Phase Alternating Line). By sequentially inputting the converted video signals to the monitor 300, a color image of the subject is displayed on the display screen of the monitor 300.

  The coaxial cable that connects the solid-state imaging device 108 and the analog signal processing unit 220 is a cable having a well-known configuration. Specifically, a coaxial cable is made by coating a core wire such as copper with an insulator such as polyethylene, covering the insulator with a shield layer that is a mesh-like braided wire knitted with a thin conductor, and protecting the insulation such as vinyl It has a structure coated with a material. The core wire is a signal line that transmits a drive control signal and an imaging signal. The braided wire is a GND wire, the tip is soldered to the GND (not shown) of the circuit board around the solid-state image sensor 108, and the base end is soldered to the GND (not shown) of the circuit board of the analog signal processing unit 220. Yes. The GND line of each coaxial cable is shown in FIG. 2 so as to be connected to different GNDs for convenience, but is soldered to a common GND on the distal end side and the proximal end side.

As shown in FIG. 2, the base ends of the GND lines of the coaxial cables CC ₁ , CC ₂ ,..., CC _n are directly connected to the GND. On the other hand, the switch SW1 is installed between the proximal end and GND GND wire of the coaxial cable CC _A. The proximal end of the GND wire of the coaxial cable CC _A, when the switch SW1 is switched to the terminal S1, is connected to the GND via the switch SW1. When the switch SW1 is switched to the terminal S2, it is connected to GND via the switch SW1 and the constant current circuit C. The system controller 202 performs switching control of the switch SW1.

FIG. 3 is an equivalent circuit diagram when the switch SW1 is switched to the terminal S2. In Figure 3, reference numeral _{R A, R 1, R 2} , shows ..., each _{R n,} coaxial cable _{CC A,} CC 1, ..., DC resistance value of the GND lines of the CC _n. A symbol a indicates a connection point between the tip of the GND line and the GND on the solid-state imaging device 108 side. The GND shown in the lower part of FIG. 3 indicates the GND on the analog signal processing unit 220 side connected to the base end of the GND line.

As shown in FIG. 3, when the current _Ia is caused to flow through the GND line of each coaxial cable by the constant current circuit C, the voltage V _gnd (= I _a · R _gnd ) is applied to both ends of the equivalent circuit. A symbol R _gnd indicates a combined resistance value of a DC resistance component of each GND line. The combined resistance value R _gnd is expressed by the following equation (1).
R _gnd = R _A + (R ₁ × R ₂ × ... × R _n ) / (R ₁ + R ₂ + ... + R _n ) (1)

The combined resistance value R _gnd changes when the GND line of the coaxial cable is disconnected. The voltage V _gnd varies with the combined resistance value R _gnd . In the present embodiment, the disconnection of the GND line of the coaxial cable is detected by detecting a change in the voltage V _gnd (indirectly according to another aspect, a change in the combined resistance value R _gnd ).

As the current _Ia is larger, the potential difference generated on both sides of the DC resistance value _RA is further increased. Therefore, a so-called GND floating problem occurs in which the GND on the solid-state imaging device 108 side has a higher potential than the GND on the analog signal processing unit 220 side. Current I _a is in order to suppress an adverse effect on the solid-state image sensor 108 due GND float, it is desirable that the breaking of the GND line is a minimum value required to accurately detect. As _a specific numerical value of the current Ia, for example, about 0.1 mA to 1.0 mA is assumed.

  FIG. 4 is a flowchart showing each processing step for detecting disconnection of the GND line of the coaxial cable. The flowchart of FIG. 4 is started when the electronic endoscope system 1 is activated. In the following description and drawings in this specification, the processing step is abbreviated as “S”.

  When the electronic endoscope system 1 is activated, the system controller 202 switches the switch SW1 to the terminal S1 (S1). The system controller 202 starts counting by an internal counter (not shown) simultaneously with switching to the terminal S1. The system controller 202 determines whether or not a predetermined time T has elapsed by counting with the internal counter (S2). The fixed time T is, for example, a time of 5 minutes or more. When a predetermined time T has elapsed since switching to the terminal S1 (S2: YES), the system controller 202 switches the switch SW1 to the terminal S2 (S3).

When the switching to the terminal S2 is performed in the processing step S3, the equivalent circuit shown in FIG. 3 is established. Therefore, current _{I a} flows in the coaxial cable, the voltage _{V gnd} occur. The system controller 202 measures the generated voltage V _gnd by the A / D circuit 202a (S4). Since the current _Ia is a constant value, the combined resistance value R _gnd is actually measured.

The system controller 202 determines whether the measured voltage _{V gnd} (or calculated based on the voltage _{V gnd} measured synthetic resistance value _{R gnd)} is a value within the specified range (S5). When the measured value (or calculated value) is a value within the specified range (S5: YES), this flowchart returns to processing step S1. When the measured value (or calculated value) is outside the specified range (S5: NO), there is a very high possibility that the GND line of at least one coaxial cable is disconnected. In such a case, the system controller 202 displays a predetermined warning message on the liquid crystal display unit of the front panel 218 or the display screen of the monitor 300 (S6), and notifies the operator of the possibility of disconnection.

The combined resistance value R _gnd changes only when one GND line is disconnected. Therefore, it is possible to detect the disconnection of the GND line at an early stage, and it is possible to prevent a problem that occurs secondary to the disconnection of the GND line. In addition, since no separate wiring is required for detecting the disconnection of the GND line, an increase in the outer diameter of the electronic scope can be effectively avoided.

  The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. For example, the analog signal processing unit 220 may be mounted on the electronic scope 100 instead of the processor 200.

The direct current resistance value of the GND line is different for each coaxial cable. Therefore, the voltage V _gnd (or the combined resistance value R _gnd ) changes according to the disconnected GND line. Therefore, in another embodiment, data on the voltage V _gnd (or the combined resistance value R _gnd ) corresponding to each disconnection pattern is collected in advance and stored in a memory or the like in the processor 200. As a result, the system controller 202 compares the above data with the measured value of the voltage V _gnd (or the calculated value of the combined resistance value R _gnd ) to identify the GND line that has a high possibility of disconnection, along with a warning message. The surgeon can be notified.

The constant current circuit C can be replaced with a constant voltage circuit constituted by, for example, a shunt regulator. In this case, the system controller 202 measures the current flowing through the equivalent circuit of FIG. 3 (or calculates the combined resistance value R _gnd based on the measured current value), and based on the measured value (or calculated value). A disconnection of the GND line is detected.

1 Electronic Endoscope System 100 Electronic Scope 200 Processor 220 Analog Signal Processing Unit

Claims (6)

An electronic scope having a solid-state image sensor at the tip;
Signal processing means for transmitting and receiving signals to and from the solid-state imaging device connected to the proximal end of the electronic scope;
A plurality of signal cables connecting the solid-state imaging device and the signal processing means;
Measuring means for measuring a combined resistance value of the GND lines of the plurality of signal cables;
Disconnection detecting means for detecting disconnection of the GND line based on a measurement result by the measuring means;
An electronic endoscope system comprising: The measuring means includes
A constant current circuit for supplying a constant current to a load circuit composed of a resistance of a GND line of the plurality of signal cables;
Voltage measuring means for measuring a voltage value applied to the load circuit;
Have
The electronic endoscope system according to claim 1, wherein the combined resistance value is calculated based on the measured voltage value. The measuring means includes
A constant voltage circuit for applying a constant voltage to a load circuit composed of a resistance of a GND line of the plurality of signal cables;
Current measuring means for measuring a current value applied to the load circuit;
Have
The electronic endoscope system according to claim 1, wherein the combined resistance value is calculated based on the measured current value.   4. The disconnection detection unit detects disconnection of the GND line when the combined resistance value is outside a predetermined specified range. 5. Electronic endoscope system.   5. The apparatus according to claim 1, further comprising a message display unit that displays a predetermined warning message on a display screen when the disconnection of the GND line is detected by the disconnection detection unit. The electronic endoscope system described in 1.   The electronic endoscope system according to any one of claims 1 to 5, wherein the signal cable is a coaxial cable.

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