WO2017221651A1

WO2017221651A1 - Coaxial cable and endoscope device

Info

Publication number: WO2017221651A1
Application number: PCT/JP2017/020226
Authority: WO
Inventors: 健児沼田
Original assignee: オリンパス株式会社
Priority date: 2016-06-20
Filing date: 2017-05-31
Publication date: 2017-12-28

Abstract

The objective of the invention is to normally decode a transmitted high-frequency differential signal. This cable is provided with a first coaxial wire and a second coaxial wire, each of the first coaxial wire and the second coaxial wire having a signal wire covered, via an insulator, by a conductor shielding, and the cross-section of each of the first coaxial wire and second coaxial wire being disposed symmetrically to one another. The endoscope device comprises this cable, an imaging unit for sending a high-frequency differential signal at one end of the signal wire, and a signal processing unit for decoding the high-frequency differential signal from another end of the signal wire.

Description

Coaxial cable and endoscope device

The present invention relates to a coaxial cable and an endoscope apparatus.
The present application claims priority based on Japanese Patent Application No. 2016-121536 filed in Japan on June 20, 2016, the contents of which are incorporated herein by reference.

The endoscope apparatus includes an imaging unit at the distal end of the insertion unit. A complementary metal oxide semiconductor (CMOS: Complementary Metal-Oxide Semiconductor) image sensor is a typical example of an image sensor that constitutes the imaging unit. A CMOS image sensor can read data at a higher speed than an image sensor charge-coupled device (CCD: Charge-Coupled Device). Therefore, it is necessary to convert the imaging signal from the CMOS imaging element into a high-frequency differential signal and transmit it through a composite coaxial line provided in the insertion portion. Some endoscope apparatuses have a structure in which an insertion section including a CCD and an insertion section including a CMOS image sensor can be attached and detached.

As exemplified in the endoscope apparatus described in Patent Document 1, a twisted pair wire may be used as a wire for transmitting a high-frequency differential signal. A wire in a twisted pair state is also called a twinax wire. The twinax line may be used for a wired local area network (LAN). This is to reduce the skew between the pairs by suppressing the change in the characteristic impedance of the high-frequency differential signal. The pair-to-pair skew means a deviation in propagation delay between differential signals.

Japanese Unexamined Patent Publication No. 2005-160925

However, when the transmitted high-frequency differential signal is deserialized and decoded into a parallel signal, inter-symbol interference (ISI: Intersymbol Interference) may occur. ISI causes high-frequency differential signals to not be decoded correctly. In particular, in an insertion portion having a length of 20 to 30 m, the pair-to-pair skew between a pair of transmitted signals becomes larger than one symbol, so that it may not be handled as a differential signal. That is, even if the received high-frequency differential signal is deserialized on the premise that the phases of the pair of transmitted signals are opposite to each other, the image signal that is a parallel signal cannot be reproduced.

The present invention has been made based on the above-described problems, and an object thereof is to provide a cable and an endoscope apparatus that can normally decode a transmitted high-frequency differential signal.

One aspect of the present invention includes a first coaxial line and a second coaxial line, and each of the first coaxial line and the second coaxial line serves as a conductor shield via an insulator. It is a cable provided with a covered signal line, the cross sections of which are arranged symmetrically.

According to the present invention, the pair-to-pair skew between the coaxial lines is suppressed, so that the transmitted high-frequency differential signal can be normally decoded.

It is a schematic block diagram which shows the structure of the endoscope apparatus which concerns on this embodiment. It is sectional drawing of the composite coaxial line which concerns on this embodiment. It is sectional drawing of an example of the conventional twinax line. It is explanatory drawing of the characteristic impedance of the coaxial line pair which concerns on this embodiment. It is a figure which shows an example of LVDS which concerns on this embodiment. It is a figure which shows the structural example of the equalizer part which concerns on this embodiment. It is a figure which shows the structural example of the equalizer part which concerns on this embodiment. It is a figure which shows the structural example of the equalizer part which concerns on this embodiment. It is a figure which shows the example of the frequency characteristic of the equalizer part which concerns on this embodiment.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram illustrating a configuration of an endoscope apparatus 1 according to the present embodiment. The endoscope apparatus 1 includes a scope unit 11, a base unit 12, and an optical adapter 13.

The scope unit 11 includes an illumination unit 111 and an insertion unit 112. The insertion portion 112 is a tubular soft portion having a long and thin shape. The insertion unit 112 includes an imaging unit 112a at one end thereof. For example, the diameter and length of the insertion portion 112 are 4 to 6 mm and 1 to 100 m, respectively. In the longitudinal direction of the insertion portion 112, the composite coaxial line 117 and the light guide portion 113 are inserted. A first connector portion 118 is fixed to the other end of the scope unit 11. The composite coaxial line 117 transmits a high-frequency differential signal converted from an imaging signal indicating an image captured by the imaging unit 112a. The image captured by the imaging unit 112a is used for various inspections. In the following description, one end and the other end of the scope unit 11 may be referred to as a distal end and a proximal end, respectively.

The base unit 12 is a main body unit of the endoscope apparatus 1 having various functions such as acquisition of an imaging signal from the scope unit 11, display of a captured image, and illumination of a subject. A second connector portion 127 is fixed to a part of the surface of the base unit 12. The second connector portion 127 is detachable from the first connector portion 118 of one scope unit 11. There are different types of the detachable scope unit 11 depending on the specifications of the illumination unit 111, the insertion unit 112, the imaging unit 112a, and the like. The specifications include, for example, the length and diameter of the insertion unit 112, the light emission intensity of the illumination unit 111, the resolution of the imaging unit 112a, the luminance, and the like.

The optical adapter 13 can be attached to and detached from the distal end of the insertion portion 112 and includes an illumination lens portion 131 and an objective lens portion 132. In a state where the optical adapter 13 is attached to the distal end of the insertion portion 112, the illumination lens portion 131 transmits light incident on the rear surface thereof from the distal end of the light guide portion 113 to the front surface. The back surface and the front surface correspond to a surface of the two main surfaces of the optical adapter 13 that faces the distal end of the insertion portion 112 and a surface that faces in the direction from the proximal end to the distal end of the insertion portion 112. The light emitted by the transmission from the illumination lens unit 131 is irradiated to the subject. The objective lens unit 132 transmits light incident on the front surface from the subject to the rear surface. The light transmitted through the illumination lens unit 131 is applied to the surface of the subject, and the reflected light reflected on the surface of the subject enters the objective lens unit 132 as image light indicating an image of the subject surface.

In addition, the user can select one type of optical adapter 13 among a plurality of types by being detachable from the distal end of the insertion unit 112. Depending on the type of the optical adapter 13, the specifications such as the optical characteristics and the observation direction of the objective lens unit 132 are different. Examples of the optical characteristics include focal length and diameter. The observation direction includes, for example, direct view and side view.

(Scope unit configuration)
Next, the configuration of the scope unit 11 according to the present embodiment will be described. The scope unit 11 includes an illumination unit 111, an insertion unit 112, a first connector unit 118, and an equalizer unit 119. The illumination unit 111, the first connector unit 118, and the equalizer unit 119 are provided at the proximal end portion of the scope unit 11.
The illumination unit 111 emits light corresponding to the electric power supplied from the illumination drive unit 122 and radiates the emitted light to the proximal end of the light guide unit 113. The illumination unit 111 is, for example, a light emitting diode (Light Emitting Diode).

The insertion unit 112 includes an imaging unit 112a, a light guide unit 113, and a composite coaxial line 117. The imaging unit 112a includes an oscillator 114, a scope lens unit 115, and an imaging element 116.

The light guide 113 receives the illumination light emitted from the illumination unit 111 at the base end and transmits the incident illumination light toward the distal end. The transmitted illumination light is emitted to the illumination lens unit 131.
The oscillator 114 generates a clock signal having a predetermined frequency. The oscillator 114 outputs the generated clock signal to the image sensor 116. The frequency is, for example, 10 MHz to 1 GHz.
The scope lens unit 115 focuses the image light incident from the objective lens unit 132 on the imaging surface of the imaging element 116 and forms an image of the subject on the imaging surface.

The imaging element 116 includes a set of a plurality of light receiving elements (not shown) and an internal circuit (not shown), an imaging drive unit (not shown), and a signal processing unit (not shown). A set of light receiving elements and internal circuits is provided for each pixel. The light receiving elements are two-dimensionally arranged on the light receiving surface at a constant interval to form a pixel array. Each of the light receiving elements generates a potential according to the intensity of the incoming light. The image sensor 116 is, for example, a CMOS image sensor using CMOS as a light receiving element. The internal circuit outputs an electric signal having a potential generated in each light receiving element to the signal processing unit based on the drive control signal input from the imaging driving unit. The imaging drive unit generates a drive control signal based on an imaging mode indicated by an imaging control signal input from an imaging signal processing unit 123 (described later) of the base unit 12 via a communication unit (described later), and the generated drive control. The signal is output to an internal circuit for each pixel. As a result, the internal circuit is driven and the imaging signal is output to the signal processing unit. The elements of the imaging mode include, for example, an electronic shutter that controls light reception on the light receiving surface, an exposure time, a frame rate, and the like.

The imaging driver generates a drive control signal by dividing or multiplying the clock signal input from the oscillator 114. The drive control signal includes, for example, a pixel clock and a synchronization signal. The synchronization signal includes a horizontal synchronization signal and a vertical synchronization signal. The pixel clock is a signal for instructing the timing of reading the potential for each pixel. The horizontal synchronization signal is a signal that indicates the start or end timing of each line constituting the image frame. The vertical synchronization signal is a signal for instructing the start or end timing of each image frame. As a result, the potential of each pixel constituting each frame is read out in a predetermined order. The imaging drive unit determines the frequency division rate according to the frame rate, the frequency division rate according to the number of lines per frame, and the frequency division rate according to the number of pixels per line, the vertical synchronization signal It is set as the frequency division ratio used for generating the synchronization signal and pixel clock. The signal processing unit converts the potential for each pixel into a signal value, and generates a digital imaging signal indicating an image of the subject. In the following description, the imaging signal generated at this point is referred to as imaging raw data, and is distinguished from an imaging signal on which another signal or data is superimposed. The signal processing unit superimposes the pixel clock and the synchronization signal on the imaging raw data, serializes the imaging signal on which these signals are superimposed, and converts the imaging signal into a pair of high-frequency differential signals. The signal processing unit sends the high-frequency differential signal obtained by the conversion to the composite coaxial line 117.

The high-frequency differential signal is, for example, LVDS (Low Voltage Differential Signal). The LVDS includes a pair of signals LVDS + and LVDS− each having a time series of one of two potential levels. Between the signals LVDS + and LVDS−, the time series of potentials are in opposite phases. In the example shown in FIG. 5, the signals LVDS + and LVDS− are time series in which the potential at each time is either V _H or V _L. One-bit information is expressed depending on whether the potential is V _H or V _L for each symbol. The sampling frequency is, for example, 100 MHz to 10 GHz. When the potential of the signal LVDS + is V _H and V _L , the potential of the signal LVDS− is V _L and V _H. The potentials V _H and V _L are potentials whose differences from the reference potential V ₀ are ΔV and −ΔV.

Note that the imaging unit 112a further includes a communication unit (not shown) and a power supply unit (not shown). The communication unit transmits / receives various control signals to / from the imaging signal processing unit 123 via the composite coaxial line 117 using a predetermined communication method. The control signal includes the above-described imaging control signal. As communication methods, for example, UART (Universal Asynchronous Receiver Transmitter, General Purpose Asynchronous Receiver / Transmitter) communication, SPI (Serial Peripheral Interface, Serial Peripheral Interface) communication, I2C (Inter-Integrated Circuit Communication, etc.) Is available. When serial communication is used as the communication method, a serial signal obtained by performing serialization processing on the control signal may be transmitted as a differential signal.

Power is supplied from the base unit 12 to the power supply unit. Power may be supplied via the composite coaxial line 117. The power supply unit converts the voltage of the supplied power into a voltage required for each component included in the imaging unit 112a. The power supply unit supplies power obtained by converting the voltage to each component.
Further, the reference potential point of the imaging unit 112 a may be grounded with a predetermined reference potential point of the base unit 12. The grounding between the reference potential points may be via the composite coaxial line 117.

The composite coaxial line 117 is a cable that includes a coaxial line pair including two coaxial lines and a separate conductor pair, and is configured by integrating them. In each of the two coaxial lines included in the composite coaxial line 117, signal lines covered with a conductor shield via an insulator are arranged in parallel in the longitudinal direction, and one and the other of the coaxial lines are arranged symmetrically with each other. It becomes. The composite coaxial line 117 is mainly used for LVDS transmission from the image sensor 116 to the equalizer unit 119. The signals LVDS + and LVDS− are transmitted using one coaxial line and the other coaxial line, respectively.
In a pair of conductors separate from the coaxial line pair, each two conductors are arranged in parallel in the longitudinal direction, and one and the other of the conductors of each conductor pair are arranged symmetrically. The point of symmetry between the coaxial lines constituting the coaxial line pair and the point of symmetry between the conductive lines constituting the conductor pair may be common. The plurality of conductor pairs are selectively used according to their respective uses such as transmission of control signals, power supply, and grounding. The configuration of the composite coaxial line 117 will be described later.

The first connector portion 118 is installed at the proximal end portion of the scope unit 11 and includes a mounting tool that can be attached to and detached from the second connector portion 127 of the base unit 12. The first connector portion 118 includes a plurality of contacts that are electrically connected between the components of the scope unit 11 and the base unit 12 while being attached to the second connector portion 127. The plurality of contacts are a high-frequency differential signal transmission from the equalizer unit 119 to the imaging signal processing unit 123, a control signal transmission between the imaging unit 112a and the imaging signal processing unit 123, and a power supply unit of the base unit 12 (see FIG. (Not shown) for power supply to the imaging unit 112a, power supply from the illumination drive unit 122 to the illumination unit 111, and grounding between the reference potential points of the scope unit 11 and the base unit 12.
By making the scope unit 11 detachable from the base unit 12, the user can select one type of scope unit 11 from among a plurality of types.

The equalizer unit 119 is an equalization unit that is connected to the base end of the composite coaxial line 117 and equalizes the frequency characteristics of a high-frequency differential signal that is input from the image sensor 116 via the composite coaxial line 117.
The equalizer unit 119 may be disposed on the first connector unit 118. In general, the frequency characteristics of the imaging device 116 and the composite coaxial line 117 are such that the gain attenuation becomes more significant as the frequency increases. Therefore, the frequency characteristics of the equalizer unit 119 are set to the inverse characteristics of the frequency characteristics obtained by multiplying the frequency characteristics of the image sensor 116 and the composite coaxial line 117. Thereby, the frequency characteristic of the amplitude of the input high frequency differential signal becomes flat. That is, the frequency characteristics are equalized. In addition, as the frequency characteristics of the equalizer unit 119, frequency characteristics corresponding to the type of the scope unit corresponding to the specifications such as the type of the imaging element, the diameter and the length of the composite coaxial line 117 may be set. The equalizer unit 119 is, for example, a passive equalizer such as a π-type equalizer or a T-type equalizer that includes a coil and a capacitor. The equalizer unit 119 outputs a high-frequency differential signal whose frequency characteristics are equalized to the imaging signal processing unit 123.

(Base unit configuration)
Next, the configuration of the base unit 12 according to the present embodiment will be described.
The base unit 12 includes a CPU (Central Processing Unit) 121, an illumination driving unit 122, an imaging signal processing unit 123, an input unit 124, a memory unit 125, a display unit 126, and a second connector unit 127.

The CPU unit 121 generates display image data indicating a display image by superimposing a predetermined graphic image on the image indicated by the image data input from the imaging signal processing unit 123. Graphic images include menu displays. The CPU unit 121 performs image processing requested according to the specifications of the display unit 126 on the generated display image data. Image processing is, for example, processing such as color space conversion, interlace / progressive conversion, and gamma conversion. The CPU unit 121 outputs display image data obtained by image processing to the display unit 126.

Further, the CPU unit 121 controls the function of the endoscope apparatus 1 based on the operation signal input from the input unit 124. For example, when the input operation signal instructs to turn on or off, the CPU unit 121 generates an illumination control signal that instructs to turn on or off, and outputs the generated illumination control signal to the illumination driving unit 122. When the input operation signal indicates the imaging mode, the CPU unit 121 generates an imaging control signal indicating the imaging mode, and outputs the generated imaging control signal to the imaging signal processing unit 123. The CPU unit 121 includes a CPU, and implements its function by reading a predetermined operation program stored in advance from the memory unit 125 and executing processing instructed by the read operation program.

The illumination drive unit 122 controls the function of the illumination drive unit 122 based on the illumination control signal input from the CPU unit 121. For example, when the input illumination control signal indicates lighting, the illumination driving unit 122 starts supplying power supplied from a power supply unit (described later) of the base unit 12 to the illumination unit 111. When the input illumination control signal indicates turning off, the illumination drive unit 122 stops supplying power to the illumination unit 111.

The imaging signal processing unit 123 amplifies the high-frequency differential signal input from the equalizer unit 119 with an amplifier (not shown), performs deserialization processing on the amplified high-frequency differential signal, and converts it into a parallel format imaging signal. Thereafter, the imaging signal processing unit 123 extracts imaging Raw data, a pixel clock and a synchronization signal superimposed on the imaging Raw data from the imaging signal. The imaging signal processing unit 123 generates image data having a signal value for each pixel indicated by the imaging raw data using the extracted pixel clock and the synchronization signal. The generated image data indicates an image of each frame. Here, the imaging signal processing unit 123 specifies the timing for acquiring the signal value of each pixel using the pixel clock, and specifies the timing at the start or end of each line and each frame using the synchronization signal. Thereby, the imaging signal processing unit 123 can specify the signal value of each frame, each line, and the signal value of each pixel in the time series of the signal values indicated by the imaging raw data. The imaging signal processing unit 123 outputs the image data generated from the imaging raw data to the display unit 126.

The imaging signal processing unit 123 controls the function of the imaging unit 112a based on the imaging control signal input from the CPU unit 121. The imaging signal processing unit 123 outputs an imaging control signal to the imaging unit 112a via the composite coaxial line 117. The imaging element 116 of the imaging unit 112a generates image data based on the imaging mode indicated by the imaging control signal input from the imaging signal processing unit 123 as described above. Therefore, the electronic shutter, exposure time, frame rate, etc. are controlled.

The input unit 124 detects a user input operation and generates an operation signal based on the detected input operation. The input unit 124 outputs the generated operation signal to the CPU unit 121. The input unit 124 may include a physical member such as a dedicated button, knob, or lever, or may include a general-purpose member such as a touch sensor or a mouse. The input unit 124 may be configured as a user interface including a general-purpose member and a guidance screen displayed on the display unit 126. The touch sensor may be integrated with the display unit 126 and configured as a touch panel.

The memory unit 125 stores various data used for processing of the CPU unit 121, various data acquired by the CPU unit 121, the above-described control program, and the like. The memory unit 125 stores the above-described operation program. For example, the memory unit 125 includes a flash memory.
The display unit 126 displays an image based on display image data input from the CPU unit 121. The display unit 126 is, for example, a liquid crystal display.
The second connector portion 127 is installed on the surface of the base unit 12. The second connector part 127 includes an attachment that can be attached to and detached from the attachment of the first connector part 118 of the scope unit 11. The mounting tool of the second connector part 127 may have a shape that fits with the mounting tool of the first connector part 118.

In addition, the base unit 12 includes a power supply unit (not shown). The power supply unit converts the voltage of the power supplied from the outside into a voltage required in each component of the base unit 12. The power supply unit supplies the power whose voltage has been converted to each component.

(Configuration example of composite coaxial cable)
Next, a configuration example of the composite coaxial line 117 according to the present embodiment will be described.
FIG. 2 is a cross-sectional view of the composite coaxial line 117 according to the present embodiment.
The composite coaxial line 117 is configured by one coaxial line pair I1 and three conductor pairs (pairs) arranged in parallel in the longitudinal direction and coupled to each other. The coaxial line pair I1 is a pair of two coaxial lines I1P and I1N. As the three conductive wire pairs, power supply lines VDD1, VDD2, ground lines GND1, GND2, and signal lines COM1, COM2 are illustrated. The entire coaxial wire pair and conductive wire pair are bundled by being wound around a bind tape BT made of an insulator. The outer surface of the bind tape BT is further covered with an overall shield OS made of a conductor. The bind tape BT fixes the entire arrangement of the coaxial wire pair and the conductive wire pair and electrically insulates them from the overall shield OS. The outer surface of the total shield OS is further covered with a total coating OC made of an insulator. Note that the outer surface of the comprehensive shield OS may not be coated with the comprehensive coating OC. In the following description, VDD1 and VDD2 may indicate a power supply voltage or a reference point of the power supply voltage, GND1 and GND2 may indicate a ground or potential reference point, and COM1 and COM2 may indicate a control signal. In the example shown in FIG. 2, the shape of the cross section of the composite coaxial line 117 is a circle.

The lengths of the coaxial lines I1P and I1N, the power supply lines VDD1 and VDD2, the ground lines GND1 and GND2, and the signal lines COM1 and COM2 correspond to the length of the composite coaxial line 117, respectively. The diameter of the composite coaxial line 117 is at least smaller than the diameter inside the insertion portion 112. Therefore, the lengths and diameters of the coaxial lines I1P and I1N, the power supply lines VDD1 and VDD2, the ground lines GND1 and GND2, and the signal lines COM1 and COM2 differ depending on the length and diameter of the insertion portion 112, respectively. The diameters of the coaxial lines I1P and I1N, the power supply lines VDD1 and VDD2, the ground lines GND1 and GND2, and the signal lines COM1 and COM2 are constant regardless of the positions in the longitudinal direction. In addition, these cross-sectional shapes are all circular.

The coaxial lines I1P and I1N are provided with conductors (core wires) IL1P and IL1N made of a conductor at the center of each. Conductive lines IL1P and IL1N are used as signal lines for transmitting signals LVDS + and LVDS−, respectively. The surroundings of the conducting wires IL1P and IL1N are covered with coaxial line shields IS1P and IS1N made of a conductor via insulators IN1P and IN1N, respectively. And the circumference | surroundings of coaxial line shield IS1P and IS1N are each covered with coaxial line film IC1P and IC1N which consist of an insulator. The coaxial line shields IS1P and IS1N can reduce the change in the characteristic impedance of the signals LVDS + and LVDS− and suppress the signal attenuation.

In the transmission of differential signals, the characteristic impedance between a pair of signals may be set to 100Ω. Copying thereto, signal LVDS +, to set the characteristic impedance of the transmission LVDS- to 100Ω is coaxial lines I1P, the characteristic impedance _R P of I1N, may be set as 50Ω to _{R N,} respectively. Since the AC component electric field generated between the coaxial lines I1P and I1N is canceled at the center line B, the coaxial line shields IS1P and IS1N are substantially grounded as shown in FIG. Therefore, the sum of the characteristic impedance _R P + _{R N} are signal LVDS +, corresponding to the impedance between LVDS-. Coaxial line I1P, respectively impedance _R P of I1N, _{R N} is not necessarily limited to 50 [Omega, if common with each other therebetween, the imaging device 116, a coaxial line I1P, can be arbitrarily set according to the specifications of the I1N.

In the composite coaxial line 117, the coaxial lines I1P and I1N are adjacent to each other, and their cross sections are in contact with each other at the symmetry point A. The symmetry point A corresponds to the midpoint of the center line B connecting the centers of the cross sections of the coaxial lines I1P and I1N. This corresponds to the fact that the respective cross sections of the coaxial lines I1P and I1N are arranged point-symmetrically with respect to the symmetry point A. The cross sections of the coaxial lines I1P and I1N are arranged symmetrically with respect to a center line C passing through the symmetry point A and perpendicular to the center line B. The center line C is a symmetrical line between the coaxial lines I1P and I1N. Here, consider a situation where the signals LVDS + and LVDS− are transmitted to the coaxial lines I1P and I1N, respectively. Since the AC components of the signals LVDS + and LVDS− are in opposite phases, the electric fields generated around the coaxial lines I1P and I1N are in opposite phases and the distribution is axisymmetric with respect to the center line B. Therefore, an antisymmetric mode component with respect to the center line C is mainly induced as a mode of the electric field generated by the AC component between the coaxial lines I1P and I1N. In general, the relative permittivity of the signal line may differ depending on the mode of the electric field generated in the signal line. However, according to the present embodiment, the anti-symmetric mode component is mainly used, and the other mode components are relatively reduced. Other mode components may be mainly caused by noise or individual differences in the configuration of the image sensor 116, the coaxial lines I1P and I1N.
Therefore, since the skew between pairs is suppressed, erroneous decoding of LVDS input to the imaging signal processing unit 123 via the composite coaxial line 117 is suppressed. As a result, the image data based on the imaging signal obtained by the decoding is normally output.

In addition, since the coaxial lines I1P and I1N are arranged adjacent to each other, the arrangement of the respective cross sections of the coaxial lines I1P and I1N is stably maintained even if the composite coaxial line 117 is bent. With this arrangement, the spread of the electric field distribution caused by the transmission of the signals LVDS + and LVDS− is suppressed, and the antisymmetric electric field distribution with respect to the center line C is stabilized. Thereby, the component of the antisymmetric mode with respect to the center line C is relatively strengthened. For this reason, the skew between pairs is suppressed, so that erroneous decoding of the imaging signal based on LVDS is suppressed.

Further, the coaxial lines I1P and I1N are respectively surrounded by being in contact with the total shield OS via the bind tape BT, and the distances from the centers of the respective cross sections of the coaxial lines I1P and I1N to the total shield OS are equal. The central point of the total shield OS is common to the symmetry point A that is the midpoint between the coaxial lines I1P and I1N. Therefore, the arrangement of the respective cross sections of the coaxial lines I1P and I1N with respect to the bending of the composite coaxial line 117 is stably maintained. Then, the spread of the electric field distribution caused by the transmission of the signals LVDS + and LVDS− is suppressed, and the antisymmetric property of the electric field distribution with respect to the center line C is stabilized.
This also emphasizes the anti-symmetric mode component relative to the center line C. For this reason, the skew between pairs is suppressed, so that erroneous decoding of the imaging signal based on the LVDS received via the composite coaxial line 117 is suppressed.

As shown in FIG. 2, in the composite coaxial line 117 whose cross-sectional shape is a circle, a conductor pair separate from the coaxial line pair I1 is integrally disposed in a region not occupied by the coaxial line pair I1. More specifically, the power supply line VDD1 is above the center line C and to the right of the center line B, the ground line GND2 is above the center line C and to the left of the center line B, and the center line C The power supply line VDD2 is disposed below the center line B and further to the left than the center line B, and the ground line GND1 is disposed below the center line C and to the right from the center line B. Upper and lower indicate regions or directions in which the coaxial lines I1P and I1N are respectively arranged in two regions divided by the center line C.
Left and right indicate one or the other of the two regions divided by the center line B, respectively. The signal line COM1 and the signal line COM2 are arranged at positions where the centers of the respective cross sections are equidistant from the symmetry point A on the center line C.

The periphery of the power supply lines VDD1 and VDD2, the ground lines GND1 and GND2, and the signal lines COM1 and COM2 are each covered with an insulator. The outer peripheries of the power supply lines VDD1 and VDD2 and the ground lines GND1 and GND2 are all in contact with the inner surface of the comprehensive shield OS via the bind tape BT. The outer periphery of the power supply line VDD1 is in contact with the outer periphery of the coaxial line I1P, the signal line COM1, and the ground line GND1, and the outer periphery of the ground line GND2 is in contact with the outer periphery of the coaxial line I1P, the signal line COM2, and the power supply line VDD2, respectively. Yes. The outer periphery of the power supply line VDD2 is in contact with the outer periphery of the coaxial line I1N, the signal line COM2, and the ground line GND2, and the outer periphery of the ground line GND1 is in contact with the outer periphery of the coaxial line I1N, the signal line COM1, and the power supply line VDD1, respectively. Yes. The outer periphery of the signal line COM1 is in contact with the outer periphery of the power supply line VDD1, the coaxial lines I1P and I1N, and the ground line GND1, and the outer periphery of the signal line COM2 is the coaxial line I1P, the ground line GND2, the power supply line VDD2, and the coaxial line I1N. Are in contact with the outer periphery of each. The diameter of each signal line or conductor decreases in the order of the coaxial line I1P, the power supply line VDD1, and the signal line COM1, and the diameter of the coaxial line I1P is the largest. The coaxial lines I1P and I1N have the same diameter. The diameters of the power supply lines VDD1 and VDD2 and the ground lines GND1 and GND2 are equal to each other. The signal lines COM1 and COM2 have the same diameter.

This arrangement and the diameter of the signal line make one coaxial line pair I1 and three conductor pairs densely packed and reduce the dead space. Since the limited space inside the insertion portion 112 through which the composite coaxial line 117 is inserted is effectively utilized, the diameter of the insertion portion 112 can be reduced. On the other hand, the cross-sectional shape of a conventional typical twinax line illustrated in FIG. 3 is an ellipse. The major axis direction is a direction in which the pair of conducting wires IL1P and IL1N are separated from each other via the insulator IN1, and the direction perpendicular to that direction is the minor axis direction. In general, since the resistance in the major axis direction is weaker than the resistance to bending in the minor axis direction, the risk of breakage due to repeated bending increases. Therefore, according to the composite coaxial line 117 according to the present embodiment, since the conducting wire is filled in the cross section having an isotropic shape, the dependency of the bending resistance on the bending direction is alleviated. Therefore, the risk of breakage that may occur due to repeated bending is reduced. The twinax wire may be formed by being twisted around a longitudinal axis in order to ensure bending resistance. In that case, since a dead space due to twisting occurs, the space inside the insertion portion 112 is not fully utilized. Further, in the composite coaxial line 117 according to the present embodiment, alternating current in the high-frequency region generated in the coaxial line pair I1 is used for transmission of the same kind of signal between the conductors arranged symmetrically with respect to the symmetry point A. The anti-symmetry of the electric field distribution due to the components is not disturbed. For this reason, even when a signal of another system is transmitted, the skew between pairs is suppressed, so that erroneous decoding of an imaging signal based on LVDS is suppressed.

For example, the power supply lines VDD1 and VDD2 are used for supplying DC power for supplying the power supply voltages VDD1 and VDD2 from the base unit 12 to the imaging unit 112a, respectively. The ground lines GND1 and GND2 are used for grounding each component of the imaging unit 112a and the potential reference points GND1 and GND2 of the base unit 12, respectively. Therefore, the electrical signals transmitted through the power supply lines VDD1 and VDD2 and the ground lines GND1 and GND2 have a direct current component as a main component. The signal lines COM1 and COM2 are used for transmission and reception of control signals COM1 and COM2 between the imaging unit 112a and the imaging signal processing unit 123, respectively. Since the control signal generally has a lower frequency than the LVDS based on the imaging signal, the electric field generated around the signal lines COM1 and COM2 does not interfere with the electric field generated around the coaxial lines I1P and I1N.
However, as the control signals COM1 and COM2, differential signals in which the phases of the AC components are opposite to each other may be used. At this time, the electric field distribution of the AC component is antisymmetric between the signal lines COM1 and COM2 across the symmetry point A, so that the antisymmetry of the electric field distribution generated in the coaxial line pair I1 is maintained.

(Configuration example of equalizer section)
Next, a configuration example of the equalizer unit 119 according to the present embodiment will be described. 6A to 6C are diagrams illustrating a configuration example of the equalizer unit 119 according to the present embodiment.
FIG. 6A shows a configuration example of the equalizer unit 119. In the example shown in FIG. 6A, the equalizer unit 119 includes a capacitor 119-1, resistance elements 119-2 to 119-4, and a coil 119-5. One end of each of the capacitor 119-1 and the resistance element 119-2 is connected to the input end. The other ends of the capacitor 119-1 and the resistance element 119-3 are connected to the output end. The other end of the resistance element 119-2 is connected to one end of the resistance element 119-3 and the resistance element 119-4. One end and the other end of the coil 119-5 are connected to the other end and the base end of the resistance element 119-4, respectively. C represents the capacitance of the capacitor 119-1. R1 represents a resistance value common to the resistance elements 119-2 and 119-3. R2 represents the resistance value of the resistance element 119-4. L represents the inductance of the coil 119-5.

FIG. 6B shows another configuration example of the equalizer unit 119. In the example shown in FIG. 6B, the equalizer unit 119 is a so-called π-type equalizer that includes a coil 119-6 and capacitors 119-7 and 119-8. One end of each of the coil 119-6 and the capacitor 119-7 is connected to the input end. The other end of the capacitor 119-7 is connected to one end and a base end of the capacitor 119-8. The other ends of the coil 119-6 and the capacitor 119-8 are connected to the output end. C1 and C2 indicate the capacitances of the capacitors 119-7 and 119-8. L represents the inductance of the coil 119-6.

FIG. 6C shows another configuration example of the equalizer unit 119. In the example shown in FIG. 6C, the equalizer unit 119 is a so-called T-type equalizer including coils 119-9 and 119-10 and a capacitor 119-11. One end of the coil 119-9 is connected to the input end. The other end of the coil 119-9 is connected to one end of the coil 119-10 and one end of the capacitor 119-11. The other end of the coil 119-10 is connected to the output end. The other end of the capacitor 119-11 is connected to the base end. C represents the capacitance of the capacitor 119-11. L1 and L2 indicate the inductances of the coils 119-9 and 119-10.

6A to 6C, coaxial lines I1P and I1N are connected to the input end and the base end, respectively, and the frequency characteristics of the voltage between the input end and the base end are equalized. The voltage between the output unit and the base end is obtained as an equalized voltage. Therefore, the circuit constants according to the respective configuration examples are set in advance so that the frequency characteristics of the equalizer unit 119 approximate the inverse characteristics of the frequency characteristics obtained by multiplying the frequency characteristics of the imaging device 116 and the composite coaxial line 117. Keep it. The circuit constant refers to the above-described capacitances C, C1, C2, resistance values R, R1, R2, inductance L, and the like. Therefore, since the equalizer unit 119 is installed at the base end of the composite coaxial line 117 in the scope unit 11, the frequency characteristics of the coaxial line pair I1 that varies depending on the diameter and length of the insertion unit 112 are flattened.

Next, an example of frequency characteristics of the equalizer unit 119 according to the present embodiment will be described. FIG. 7 is a diagram illustrating an example of frequency characteristics of the equalizer unit 119 according to the present embodiment. The vertical axis and the horizontal axis indicate gain and frequency, respectively. A solid line, a broken line, and an alternate long and short dash line indicate frequency characteristics of the coaxial line pair I1, the equalizer unit 119, and the equalized coaxial line pair I1, respectively. In the example shown in FIG. 7, the gain of the coaxial line pair I1 is substantially constant in a frequency band of 10 MHz or less, but when it exceeds 10 MHz, the higher frequency component attenuates and approximates to zero. On the other hand, the gain of the equalizer unit 119 is substantially constant in a frequency band of 10 MHz or less, but when the frequency exceeds 10 MHz, higher frequency components are amplified. This frequency characteristic is a frequency characteristic obtained using the configuration shown in FIG. 6A. The gain of the coaxial line pair I1 after equalization is within 6 dB in the gain range up to the frequency band of 1 GHz or less, and the width of the frequency band in which the gain is substantially constant is expanded to 1 GHz. Note that the circuit constant of the equalizer unit 119 may be adjusted for each individual in order to eliminate individual differences in frequency characteristics such as the image sensor 116 and the composite coaxial line 117. In the adjustment, the width of the frequency band in which the gain of the equalized coaxial line pair I1 is within a predetermined range (for example, within 6 dB) is made as wide as possible. As described above, the equalizer unit 119 can suppress the attenuation of the high-frequency component that is the main component of the LVDS by flattening the frequency characteristics. Since intersymbol interference caused by interference with other components is suppressed, erroneous decoding of LVDS is suppressed.

As described above, the composite coaxial line 117 according to the present embodiment includes the coaxial lines I1P and I1N, and the coaxial lines I1P and I1N respectively include the conductor coaxial line shield IS1P and the conductor IN1P and IN1N, respectively. Conductive wires IL1P and IL1N covered with IS1N are provided. Further, the respective cross sections of the coaxial line I1P and the coaxial line I1N are arranged symmetrically.
With this configuration, when a high-frequency differential signal having phases opposite to each other is transmitted to each of the conductive wires IL1P and IL1N, an electric field of an AC component that is antisymmetric with respect to each cross section is mainly induced. Since the pair-to-pair skew between the coaxial lines I1P and I1N is suppressed, the high-frequency differential signal transmitted to the imaging signal processing unit 123 is normally decoded.

In addition, the composite coaxial line 117 according to the present embodiment includes an equalizer section 119 that equalizes the frequency characteristics of the high-frequency differential signal transmitted from one end of the conducting wires IL1P and IL1N at the proximal ends of the conducting wires IL1P and IL1N. The imaging signal processing unit 123 acquires an imaging signal by decoding a signal obtained by amplifying the high-frequency differential signal input from the equalizer unit 119 with an amplifier.
With this configuration, attenuation of a high-frequency differential signal whose main component is a high-frequency component is suppressed, so that the inter-pair skew between the coaxial lines I1P and I1N is suppressed. For this reason, the high-frequency differential signal transmitted to the imaging signal processing unit 123 is normally decoded. Further, by providing the base end of the composite coaxial line 117, at least frequency characteristics corresponding to the specifications of the composite coaxial line 117 are set in advance, and equalization based on the set frequency characteristics is performed. Therefore, by replacing the scope unit 11 integrated with the composite coaxial line 117, equalization suitable for the specifications of the composite coaxial line 117 having various specifications is performed.

Further, in the composite coaxial line 117 according to the present embodiment, the coaxial lines I1P and I1N are covered with insulating coaxial line coatings IC1P and IC1N, respectively, and between the center points of the respective cross sections of the coaxial lines I1P and I1N. They touch each other at a point of symmetry A that is a point.
With this configuration, the spread of the electric field distribution induced by the transmitted high-frequency differential signal is suppressed. Further, the symmetrical positional relationship between the coaxial lines I1P and I1N due to bending is stabilized. Since the anti-symmetric electric field distribution induced mainly is stabilized, skew between pairs is further suppressed, so that erroneous decoding of an imaging signal based on LVDS is further suppressed.

Further, in the composite coaxial line 117 according to the present embodiment, both the coaxial lines I1P and I1N are covered with the conductor total shield OS, and the cross-sectional shape of the total shield is symmetric with respect to the symmetry point A.
With this configuration, the spread of the electric field distribution induced by the transmitted high-frequency differential signal is suppressed. Further, the symmetrical positional relationship between the coaxial lines I1P and I1N due to bending is stabilized. Since the anti-symmetric electric field distribution induced mainly is stabilized, skew between pairs is further suppressed, so that erroneous decoding of an imaging signal based on LVDS is further suppressed.

The composite coaxial line 117 according to the present embodiment further includes a pair or a plurality of pairs of conducting wires.
The centers of the cross-sections of one of the pair of conductive wires and the other are arranged symmetrically with respect to the symmetry point A.
With this configuration, separate conductors are provided in regions of the composite coaxial line 117 that are not occupied by the coaxial lines I1P and I1N. Therefore, it is possible to effectively use the limited space inside the insertion portion 112 into which the composite coaxial line 117 is inserted, and to reduce the diameter of the insertion portion 112 inserted into the subject. In addition, since the electric field distribution induced by separate differential signals transmitted to one and the other of each pair of conductors is antisymmetric with respect to the symmetry point A, the induction is mainly induced around the coaxial lines I1P and I1N. The antisymmetric electric field distribution is maintained. Since the pair-to-pair skew is not promoted by transmission of a separate differential signal, erroneous decoding of the imaging signal based on LVDS is suppressed.

In the composite coaxial line 117 according to the present embodiment, each of the pair or plural pairs of conductors is in contact with at least one of the other conductors among the coaxial lines I1P and I1N and the pair or plural pairs of conductors, and the pair or plural pairs. Each of at least a pair of conducting wires is in contact with the general shield OS via a bind tape BT covering the coaxial wires I1P and I1N.
With this configuration, in the composite coaxial line 117, the conducting wires provided separately from the coaxial lines I1P and I1N are densely arranged in an isotropic space covered with the comprehensive shield OS. Therefore, it is possible to further effectively utilize the limited space to further reduce the diameter of the insertion portion, and to increase the bending resistance.

In addition, the endoscope apparatus 1 according to the present embodiment includes a composite coaxial line 117, an imaging unit 112a that outputs a high-frequency differential signal to the distal ends of the conducting wires IL1P and IL1N, and a high-frequency difference from the proximal ends of the conducting wires IL1P and IL1N. An imaging signal processing unit 123 that decodes the motion signal.
With this configuration, high-frequency differential signals that carry captured images whose phases are opposite to each other are transmitted to the conductors IL1P and IL1N, respectively, and an electric field of an AC component that is antisymmetric with respect to each cross section is mainly used. Induced. Since the pair-to-pair skew between the coaxial lines I1P and I1N is suppressed, the imaging signal processing unit 123 can normally decode the high-frequency differential signal from the base ends of the conductive lines IL1P and IL1N.

In the above-described embodiment, the case where the number of the pair of conductors separate from the coaxial line pair I1 included in the composite coaxial line 117 is three is an example, but it is one, two, four or more. May be. Any of these conducting wire pairs, or any combination thereof, may be a coaxial wire pair having a configuration similar to that of the coaxial wire pair I1. Further, the light guide portion 113 may be inserted through the composite coaxial line 117. Further, the space inside the bind tape BT of the composite coaxial line 117 may be further filled with an insulator other than air, for example, polyethylene.

In addition, you may make it implement | achieve a part of endoscope apparatus 1 which concerns on embodiment mentioned above, for example, the CPU part 121, and the imaging signal process part 123 with a computer. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed. Here, the “computer system” is a computer system built in the endoscope apparatus, and includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM or a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In this case, a volatile memory inside a computer system that serves as a server or a client may be included that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

Also, a part or all of the endoscope apparatus 1 according to the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each functional block of the endoscope apparatus 1 may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to the advancement of semiconductor technology, an integrated circuit based on the technology may be used.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment and its modification. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention.
Further, the present invention is not limited by the above description, and is limited only by the scope of the appended claims.

DESCRIPTION OF SYMBOLS 1 Endoscope apparatus 11 Scope unit 12 Base unit 13 Optical adapter 111 Illumination part 112 Insertion part 112a Imaging part 113 Light guide part 114 Oscillator 115 Scope lens part 116 Imaging element 117 Compound coaxial line 118 First connector part 119 Equalizer part 119- 1, 119-7, 119-8, 119-11 Capacitor 119-2, 119-3, 119-4 Resistance element 119-5, 119-6, 119-9, 119-10 Coil 121 CPU part 122 Illumination drive part 123 Image pickup signal processing unit 124 Input unit 125 Memory unit 126 Display unit 127 Second connector unit 131 Illumination lens unit 132 Objective lens unit BT Bind tape COM1, COM2 Signal line GND1, GND2 Ground line I1 Coaxial line pair I1P, I1N Coaxial IC1P, IC1N coaxial line coating IL1P, IL1N wire IN1, IN1P, IN1N insulator IS1P, IS1N coaxial line shield OC Overall coating OS overall shield VDD 1, VDD2 power supply line

Claims

A first coaxial line and a second coaxial line;
Each of the first coaxial line and the second coaxial line is:
It has a signal line covered with a conductor shield through an insulator,
A cable in which the respective cross sections are arranged symmetrically.
The cable according to claim 1, further comprising an equalization unit that equalizes frequency characteristics of a signal transmitted from one end of the signal line at the other end of the signal line.
Each of the first coaxial line and the second coaxial line is:
Covered with an insulating covering,
The cable according to claim 1, wherein the cables are in contact with each other at a midpoint between center points of the respective cross sections.
Both the first coaxial line and the second coaxial line are covered with a conductor covering member,
The cable according to claim 3, wherein a shape of a cross section of the covering member of the conductor is symmetric with respect to the midpoint.
Further comprising one or more pairs of conductors;
The cable according to any one of claims 3 and 4, wherein the center of each cross section of one of the pair of conductive wires is arranged symmetrically with respect to the midpoint.
Each of the one or more pairs of conducting wires is
In contact with at least one of the first coaxial line, the second coaxial line, and the conducting wire among other conducting wires;
6. The cable according to claim 5, wherein each of at least a pair of the conductors out of the pair or the plurality of pairs of conductors is in contact with a covering member that covers the first coaxial line and the second coaxial line.
A cable according to any one of claims 1 to 6,
An imaging unit that outputs a high-frequency differential signal to one end of the signal line;
A signal processing unit for decoding a high-frequency differential signal from the other end of the signal line;
An endoscope apparatus comprising: