WO2017187535A1 - Endoscope device and temperature inspection method - Google Patents

Abstract

This endoscope device has, on a tip of an insertion portion, members having different electrical characteristics according to the temperature and a physical quantity other than the temperature, and includes: a detection unit that detects a characteristic value of each electrical characteristic; a storage unit that stores temperature characteristic information that indicates a temperature characteristic of the characteristic value; and an inspection unit that inspects, on the basis of the characteristic value of each physical quantity, a measured condition of the temperature specified by referring to the temperature characteristic information from the characteristic value.

Description

Endoscope apparatus and temperature inspection method

The present invention relates to an endoscope apparatus and a temperature inspection method.

Endoscope devices are used in various fields to observe the inside of a space that cannot be directly observed from the outside. For example, observation of organs in body cavities, and treatment and treatment of medical equipment using boilers as necessary, observation and inspection of internal scratches, corrosion, etc. in boilers, turbines, engines, chemical plants, etc. There are industrial fields, etc. Some endoscope apparatuses include an electrical member at the distal end of an insertion portion to be inserted into a subject.

As the electrical member, an imaging member and a lighting member are typical as exemplified below. Examples of the imaging member include a solid-state imaging device such as a CCD (Charge Coupled Device) sensor and a CMOS (Complementary Metal Oxide Semiconductor) sensor. Illuminating members include light emitting elements such as LEDs (Light Emitting Diodes) and LDs (Laser Diodes).
In addition, the electrical member provided in the endoscope apparatus may include passive electrical components. Passive electrical components include, for example, passive elements such as resistance elements, capacitors, and coils.

Depending on the subject to be observed, the temperature at the observation location may become high. In that case, the temperature of the solid-state image sensor provided in the insertion part of the endoscope apparatus may rise. In addition, the temperature of the solid-state imaging device may rise due to illumination light that illuminates the subject. This rise in temperature causes an increase in dark current generated in the solid-state imaging device, and causes a deterioration in image quality of the observed image. Further, when the temperature rises, the solid-state image sensor may be destroyed. In a light emitting element, the amount of light emission may change, and the quality of an observed image may deteriorate.

For example, it has been proposed to estimate the temperature without providing a separate temperature sensor by utilizing the fact that the dark current of the solid-state imaging device changes with temperature, as in the imaging device described in Patent Document 1.
Further, as in the light emission control device described in Patent Document 2, it is proposed that the forward voltage of the LED is detected to calculate the ambient temperature, adjust the driving current of the light emitting element, and adjust the light emission intensity. ing.

Japanese Unexamined Patent Publication No. 2010-11116 Japanese Unexamined Patent Publication No. 2005-129598

However, in the imaging device disclosed in Patent Document 1, depending on the imaging device, there may be a noticeable variation in signal level (shading) between pixels. For this reason, an error may occur in the temperature due to individual output pixels or individual differences in shading.
Further, the light emission control device described in Patent Document 2 does not include means for confirming whether the temperature estimated from the detected forward voltage is normal. For this reason, if a failure occurs in the measurement of the forward voltage, the temperature may not be measured normally.

The present invention has been made in consideration of such problems, and provides an endoscope apparatus and a temperature inspection method capable of inspecting an operation state of a temperature measurement function while using main functions of members. For the purpose.

According to a first aspect of the present invention, there is provided a detection unit for detecting a characteristic value of the electrical characteristic, including a member having a different electrical characteristic according to a temperature and a physical quantity distinct from the temperature at a distal end of the insertion part, and the characteristic A storage unit that stores temperature characteristic information indicating a temperature characteristic of the value, and an inspection unit that inspects the measurement state of the temperature specified by referring to the temperature characteristic information from the characteristic value based on the characteristic value for each physical quantity And an endoscope apparatus.

According to a second aspect of the present invention, in the first aspect, a plurality of members having different electrical characteristics depending on the temperature are provided at the distal end of the insertion portion, and the characteristic value of the electrical characteristics is set for each of the members. A detection unit for detecting, a storage unit for storing temperature characteristic information indicating a temperature characteristic of the characteristic value, and a temperature measurement state specified from the characteristic value with reference to the temperature characteristic information for each member And an inspection unit that inspects based on the comparison of the characteristic values.

According to a third aspect of the present invention, in the second aspect, the inspection unit calculates a change amount from the start of measurement of the temperature for each member, and based on the change amount for each member. The measurement state may be inspected.

According to a fourth aspect of the present invention, in any one of the first to third aspects, at least one of the members is a light emitting element that emits light in response to current supply, and the detection unit The voltage generated according to the supply of the current is detected as the characteristic value of the light emitting element, and the storage unit includes information indicating the temperature characteristic of the voltage generated according to the supply of the current as the temperature characteristic information. Remember.

According to a fifth aspect of the present invention, in the fourth aspect, the luminance detection unit that detects the luminance of the light from the light emitting element and the storage unit are configured to transmit light that is emitted in response to the supply of the current. Luminance temperature characteristic information indicating a temperature characteristic of luminance is stored, and the inspection unit is identified from the voltage with reference to the temperature with reference to the luminance temperature characteristic information and the temperature with reference to the temperature characteristic information. The measured state of the temperature may be inspected by comparing the measured temperature.

According to a sixth aspect of the present invention, in any one of the second to fifth aspects, the other one of the members is an image sensor that photoelectrically converts incoming light, and the detection unit Detects a dark current generated in the image sensor as the characteristic value of the image sensor, and the storage unit further stores dark current temperature characteristic information indicating a temperature characteristic of the dark current as the temperature characteristic information. .

According to a seventh aspect of the present invention, there is provided a method for an endoscope apparatus, comprising: a member provided at a distal end of an insertion portion; and a member having different electrical characteristics according to a temperature and a physical quantity separate from the temperature. A detection step for detecting a characteristic value of the electrical characteristic; a temperature specified by the characteristic value detected in the detection step with reference to temperature characteristic information stored in a storage unit and indicating the temperature characteristic of the characteristic value; An inspection step for inspecting a measurement state based on a characteristic value for each physical quantity, and a temperature inspection method.

An eighth aspect of the present invention is a method in an endoscope apparatus, wherein a plurality of members are provided at the distal end of an insertion portion, and each of the members has different electrical characteristics depending on temperature. A detection step for detecting the characteristic value, and temperature characteristic information stored in the storage unit and indicating the temperature characteristic of the characteristic value, and the temperature measurement state specified from the characteristic value is determined for each member And a test step for testing based on the comparison of the characteristic values.

According to the endoscope apparatus and the temperature measurement method of each aspect of the present invention, the operation state of the temperature measurement function can be inspected while using the main functions of the members.

It is a schematic block diagram which shows the structural example of the endoscope apparatus which concerns on 1st Embodiment. It is a schematic circuit diagram which shows the structural example of the drive circuit which concerns on 1st Embodiment. It is a figure which shows an example of the temperature characteristic of a forward voltage. It is a flowchart which shows an example of the temperature measurement process which concerns on 1st Embodiment. It is a flowchart which shows an example of the temperature test process which concerns on 1st Embodiment. It is a schematic block diagram which shows the structure of the endoscope apparatus which concerns on 2nd Embodiment. It is a flowchart which shows an example of the temperature test process which concerns on 2nd Embodiment. It is a schematic block diagram which shows the structure of the endoscope apparatus which concerns on 3rd Embodiment. It is a conceptual diagram which shows the example of the output signal input from the signal driver which concerns on 3rd Embodiment. It is a figure which shows an example of the amount of dark current accumulation charges. It is a figure which shows an example of the temperature dependence of the dark current which arises in a photodiode. It is a figure which shows an example of the frequency distribution of the difference value of the signal value between frames. It is a flowchart which shows an example of the temperature test process which concerns on 3rd Embodiment. It is a schematic block diagram which shows the structure of the endoscope apparatus which concerns on the modification of 3rd Embodiment. It is a figure which shows an example of the temperature characteristic of the relative luminance of LED. It is a flowchart which shows an example of the temperature test process which concerns on the modification of 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
FIG. 1 is a schematic block diagram illustrating a configuration example of an endoscope apparatus 10 according to the first embodiment of the present invention.
The endoscope apparatus 10 includes an insertion unit 11 and a housing 12.
The insertion portion 11 is configured to include a tube material having an elongated shape whose length in one direction is longer than the other direction. The distal end portion which is one end in the longitudinal direction of the insertion portion 11 includes a lens 111, two LEDs 112-1 and 112-2, an image sensor 113 and a signal driver 114. The tip is a part that is first inserted or approached to the subject. In the following description, the other end in the longitudinal direction of the insertion portion 11 is referred to as a base end or a base end portion. A conducting wire penetrates the insertion portion 11 in the longitudinal direction. The conductors are respectively the current from the power supply terminal Vcc stored in the housing 12 to the LEDs 112-1 and 112-2, the current from the LEDs 112-1 and 112-2 to the current sources 132-1 and 132-2, and the signal driver. It is used for transmission of an image signal from 114 to the image processing unit 136.

The lens 111 is installed at the distal end of the insertion portion 11. The direction of the optical axis of the lens 111 is parallel to the longitudinal direction of the insertion portion 11. The lens 111 is a convex lens that transmits light incident from one side surface to the other side surface.

The LEDs 112-1 and 112-2 are light-emitting elements that convert electric power supplied by the drive current into light, respectively. One end of each of the LEDs 112-1 and 112-2 is electrically connected to a common power supply terminal Vcc. The other ends of the LEDs 112-1 and 112-2 are electrically connected to the current sources 132-1 and 132-2. Forward currents flowing from the power supply terminal Vcc to the current sources 132-1 and 132-2 are supplied as driving currents to the LEDs 112-1 and 112-2, respectively. The light emitting surfaces of the LEDs 112-1 and 112-2 are directed toward the tip of the insertion portion 11, and light emitted from the LEDs 112-1 and 112-2 is emitted from the tip of the insertion portion 11, respectively. Therefore, the LEDs 112-1 and 112-2 mainly function as illumination that emits light to the surface of the subject. As will be described later, the voltage between both terminals of the LED 112-1 is detected as a forward voltage by the A / D 133 stored in the housing 12. This forward voltage is used to specify the temperature of the LED 112-1.

The image sensor 113 includes a plurality of pixels that photoelectrically convert light incident from the lens 111 into an output signal that is an electrical signal. The imaging device is, for example, a CCD image sensor, a CMOS image sensor, or the like that includes a photodiode for each pixel. The plurality of pixels are two-dimensionally arranged at predetermined spatial intervals on the imaging surface of the image sensor 113. The imaging surface is orthogonal to the optical axis of the lens 111 and is irradiated with incident light focused by the lens 111. Therefore, an image of the subject is formed on the imaging surface. A region where pixels are arranged on the imaging surface corresponds to a pixel region. The image sensor 113 reads out an output signal from each pixel in response to an input of an imaging control signal from the signal driver 114, and outputs the read output signal to the signal driver 114.

The signal driver 114 generates an imaging control signal for controlling imaging by the imaging element 113. The imaging control signal is a control signal for controlling the exposure time for the pixels included in the imaging element 113 and the timing for reading the output signal from each pixel. The imaging control signal is, for example, a drive pulse for instructing the output order of the output signal for each pixel in a predetermined frame cycle for the pixels arranged in the pixel region of the image sensor 113 (for example, raster scan order). . Each pixel includes, for example, a photodiode having a PN junction where a P-type semiconductor made of silicon and an N-type semiconductor are in contact. Charge is accumulated in each pixel as time passes. Each pixel releases the accumulated charge in response to the input of the imaging control signal from the signal driver 114. From the pixel, an output signal indicating a voltage generated by releasing the charge as a signal value is output. Therefore, the exposure time substantially corresponds to the frame period (that is, the reciprocal of the frame rate). Here, charge accumulation in each pixel is mainly caused by photoelectric conversion with respect to incident light.
The signal driver 114 reads out an output signal for each pixel from the image sensor by outputting an imaging control signal to the image sensor 113. The signal driver 114 outputs the read output signal for each pixel to the image processing unit 136.

The endoscope apparatus 10 further includes a power supply terminal Vcc, two current sources 132-1 and 132-2, an A / D 133, a temperature calculation unit 134, an inspection unit 135, an image processing unit 136, a display unit 138, a memory 139, and a control. The unit 140 and the drive circuit 151 (FIG. 2) are included. These parts are all housed in the housing 12 and configured as a main body of the endoscope apparatus 10. In FIG. 1, the drive circuit 151 is not shown.

The power supply terminal Vcc is a positive terminal to which the drive circuit 151 is electrically connected. The drive current generated by the drive circuit 151 is supplied to the LEDs 112-1 and 112-2 as a forward current through the power supply terminal Vcc.

The current sources 132-1 and 132-2 are electric circuits that maintain the current value of the current flowing between both ends at a predetermined current value. Each of the current sources 132-1 and 132-2 includes a variable resistance element (not shown) for adjusting the current value, and is configured by connecting the variable resistance elements in series. One end of each of the current sources 132-1 and 132-2 is electrically connected to the other end of the LEDs 112-1 and 112-2. The other ends of the current sources 132-1 and 132-2 are grounded. The current source 132-1 controls the current value of the current flowing between both ends thereof to be equal to the current value of the forward current indicated by the current control signal input from the control unit 140. In the following description, the current value of the forward current may be simply referred to as the forward current.

One end and the other end of an A / D (Analog-to-Digital; analog / digital converter) 133 are electrically connected to one end and the other end of the LED 112-1, respectively. The A / D 133 converts the voltage between one end and the other end of the LED 112-1 that is an analog signal into forward voltage data that indicates the voltage value of the forward voltage that is digital data. The forward voltage means a voltage generated at both ends of the LED 112-1 or a voltage value of the voltage when a forward current that is a current supplied from the power supply terminal Vcc is supplied. The forward voltage varies depending on the forward current supplied to the LED 112-1. The A / D 133 detects the forward voltage V1 of the LED 112-1 as a characteristic value indicating the electrical characteristics of the LED 112-1 under a predetermined forward current I1. The A / D 133 detects the forward voltage V2 of the LED 112-1 under the forward current I2. The forward currents I1 and I2 are instructed by a current control signal input from the control unit 140. Further, the forward current I2 has a current value different from that of the forward current I1. The A / D 133 outputs the forward voltage data indicating the detected forward voltage V1 and forward voltage V2 to the temperature calculation unit 134.

The temperature calculation unit 134 reads the forward voltage versus ambient temperature table stored in the memory 139 in advance. The forward voltage vs. ambient temperature table is data indicating the correspondence between the forward voltage supplied to the LED 112-1 and the ambient temperature. The ambient temperature means the temperature around the LED 112-1. That is, the forward voltage vs. ambient temperature table is data indicating the temperature characteristic of the forward voltage generated by the forward current passing through the LED 112-1 as one kind of the electrical characteristics of the LED 112-1. The temperature calculation unit 134 refers to the forward voltage vs. ambient temperature table, the temperature T (V1) corresponding to the forward current I1 and the forward voltage V1, and the temperature corresponding to the forward current I2 and the forward voltage V2. Specify T (V2). The temperature calculation unit 134 outputs temperature data indicating the specified temperature T (V1) and temperature T (V2) to the inspection unit 135.

The inspection unit 135 inspects the measurement state of the temperature specified from the forward voltage of the LED 112-1 based on the temperature T (V1) and the temperature T (V2) indicated by the temperature data input from the temperature calculation unit 134. . The inspection unit 135 compares the temperature T (V1) and the temperature T (V2) to determine whether the temperature T (V1) or the temperature T (V2) is appropriate as the measurement state. More specifically, the inspection unit 135 determines that the difference | T (V1) −T (V2) | between the temperature T (V1) and the temperature T (V2) is a predetermined difference threshold ε (for example, 0.1 °). C is determined to be appropriate when it is smaller than 0.3 ° C., and inappropriate when the difference is equal to or greater than a predetermined difference threshold ε. Note that the determination target may be either the temperature T (V1) or the temperature T (V2) that is the comparison target. In the following description, the case where the determination target is mainly the temperature T (V1) is taken as an example, including other embodiments and modifications.
When determining that the temperature T (V1) is appropriate, the inspection unit 135 further inspects whether or not the temperature T (V1) is within a predetermined usable temperature range. The usable temperature is a temperature range in which an expected function can be achieved by normal use of the endoscope apparatus 10 and the structure thereof is not significantly damaged or deteriorated. The usable temperature is, for example, in the range from −10 ° C. to 70 ° C.

The inspection unit 135 outputs display information corresponding to the determination result to the display unit 138. For example, when it is determined that the temperature T (V1) is inappropriate or when it is determined that the temperature T (V1) is not within the usable temperature range, the inspection unit 135 is stored in advance from the memory 139. Read warning information. Then, the inspection unit 135 outputs the read warning information to the display unit 138. On the display unit 138, warning information input from the inspection unit 135 is displayed. The warning information is information for notifying the user that the specified temperature T (V1) is inappropriate or that the specified temperature T (V1) is not within the usable temperature range.

Note that the warning information that the inspection unit 135 outputs to the display unit 138 is determined when the temperature T (V1) is determined to be inappropriate and when the temperature T (V1) is determined not to be within the usable temperature range. May be different. That is, when determining that the temperature T (V1) is inappropriate, the inspection unit 135 outputs warning information indicating that the measured temperature T (V1) is inappropriate to the display unit 138. When determining that the temperature T (V1) is not within the usable temperature range, the inspection unit 135 outputs warning information indicating that the temperature T (V1) is not within the usable temperature range to the display unit 138. . The warning information may include an instruction to stop using the endoscope apparatus 10 or an instruction to wait until the temperature T (V1) changes within the usable temperature range.

When determining that the temperature T (V1) is appropriate, the inspection unit 135 generates temperature information indicating the temperature T (V1) and outputs the generated temperature information to the display unit 138. The display unit 138 displays the temperature T (V1) as temperature information input from the inspection unit 135.
Note that the format of the information to be displayed may be any message, symbol, figure, or image made up of predetermined characters. Also, the format of information presented as warning information is not limited to a format that can be visually recognized, and may be audio information. In that case, the endoscope apparatus 10 further includes an audio reproduction unit (not shown). For example, the sound reproducing unit includes a speaker. The inspection unit 135 outputs the warning information to the audio reproduction unit. The sound reproducing unit reproduces sound indicating the warning information input from the inspection unit 135.

The image processing unit 136 aggregates the signal values indicated by the output signals for each pixel input from the signal driver 114 for each frame, and generates an image signal indicating the signal value (pixel value) for each pixel. The image signal is a signal indicating an image of the subject. The image processing unit 136 performs predetermined image processing on the generated image signal. Examples of the predetermined image processing include A / D conversion, γ correction, YC conversion, resizing, and the like. The image processing unit 136 outputs an image signal obtained by performing predetermined image processing to the display unit 138. Note that the image processing unit 136 may store the image signal in the memory 139. Thereby, the captured image of the subject is recorded.

The display unit 138 displays characters, symbols, figures, or images based on the warning information input from the inspection unit 135. The display unit 138 displays an image based on the image signal input from the image processing unit 136. When the warning information and the image signal are input at the same time, the display unit 138 may superimpose characters based on the warning information and the image based on the image signal and display a display image obtained by the superimposition.
The display unit 138 includes a display device such as a liquid crystal display (LCD) or an electro-luminescence (EL) display. The display unit 138 may include a structure that can be detachably fixed to the main body of the endoscope apparatus 10.

The memory 139 stores various data used by each unit of the endoscope apparatus 10 for processing and data generated by each unit as described above. The memory 139 includes, for example, a nonvolatile storage medium such as EEPROM (Electrically Erasable Programmable Read-Only Memory) and a volatile storage medium such as DRAM (Dynamic Random Access Memory).

The control unit 140 controls various operations of the endoscope apparatus 10. For example, when inspecting the temperature measurement state, the control unit 140 generates a current control signal for controlling the forward current supplied to the LED 112-1, and outputs the generated current control signal to the current source 132-1. To do. The control unit 140 sequentially generates the current control signal indicating the forward current I1 and the current control signal indicating the forward current I2 described above as current control signals. When the current control signal input from the control unit 140 indicates the forward current I1, the current source 132-1 has a forward current control signal indicating the current value of the current supplied from the power supply terminal Vcc via the LED 112-1. Control to directional current I1. When the current control signal input from the control unit 140 indicates the forward current I2, the current source 132-1 has a forward current control signal indicating the current value of the current supplied from the power supply terminal Vcc via the LED 112-1. Control to directional current I2.

Further, the control unit 140 generates a light emission control signal for controlling whether or not light is emitted from the LEDs 112-1 and 112-2, and outputs the generated light emission control signal to the drive circuit (FIG. 2). When the light emission control signal input from the control unit 140 indicates that light emission is required (ON), the drive circuit generates a drive current and supplies the generated drive current to the LEDs 112-1 and 112-2 via the power supply terminal Vcc. . When the light emission control signal input from the controller 140 indicates that light emission is not required (OFF), the drive circuit stops generating and supplying the drive current.

Also, the control unit 140 generates a display control signal for controlling whether to display or record the captured image of the subject, and outputs the generated display control signal to the image processing unit 136. When the display control signal input from the control unit 140 indicates that display is required (ON), the image processing unit 136 outputs the generated image signal to the display unit 138. When the display control signal input from the control unit 140 indicates that display is not required (OFF), the image processing unit 136 stops outputting the image signal to the display unit 138. When the display control signal input from the control unit 140 indicates that recording is required (ON), the image processing unit 136 stores the generated image signal in the memory 139. When the display control signal input from the control unit 140 indicates that recording is not required (OFF), the image processing unit 136 stops storing the image signal in the memory 139.

Note that the control unit 140 may realize the function by executing processing instructed by a predetermined control program. The endoscope apparatus 10 may further include, for example, an operation input unit (not shown), and the control unit 140 may constitute a user interface in cooperation with the operation input unit and the display unit 138. The operation input unit accepts a user operation and outputs an operation signal indicating a user-desired function to the control unit 140 in accordance with the operation. The operation signal is a function of the endoscope apparatus 10, for example, whether or not the temperature measurement state needs to be inspected, whether or not the LEDs 112-1 and 112-2 emit light, whether or not the image captured by the image sensor 113 is displayed, This is a signal for instructing whether or not to record the image. It should be noted that the inspection of the temperature measurement state may be continuously performed during the light emission of the LED 112-1, or may be performed every predetermined time (for example, at intervals of 1 to 15 minutes). The operation input unit may include a dedicated member such as a button or a knob, or may include a general-purpose member such as a mouse or a touch sensor.

(Drive circuit)
Next, a configuration example of the drive circuit 151 connected to the power supply terminal Vcc will be described.
FIG. 2 is a schematic circuit diagram illustrating a configuration example of the drive circuit 151. The drive circuit 151 is an electric circuit that includes a power source 152 and a variable resistance element 153. One end of the power source 152 is electrically connected to one end of the variable resistance element 153, and the other end of the power source 152 is grounded. The other end of the variable resistance element 153 is connected to one end of the LEDs 112-1 and 112-2 via the power supply terminal Vcc. The current from the power supply 152 is supplied to one end of the LEDs 112-1 and 112-2 via the variable resistance element 153 and the power supply terminal Vcc. In FIG. 2, the LED 112-2 of the two LEDs 112-1 and 112-2 is not shown, and the LED 112-1 is shown as a measurement target of the forward voltage Vf that is the voltage across the LED 112-1. It should be noted that the forward current If supplied to the LED 112-1 can also be adjusted by adjusting the resistance value of the variable resistance element 153.

(Relationship between ambient temperature and forward voltage)
Next, the relationship between the ambient temperature, which is the temperature of the LED 112-1, and the forward voltage will be described. FIG. 3 is a diagram illustrating an example of temperature characteristics of the forward voltage. In FIG. 3, the horizontal axis and the vertical axis indicate the ambient temperature T and the forward voltage Vf, respectively. The three curves show the forward voltage generated across the LED 112-1 when the forward currents are I1, I2, and I3, respectively. For a certain forward current If, the forward voltage Vf decreases as the ambient temperature T increases and increases as the ambient temperature T decreases. The higher the ambient temperature T, the lower the rate of change of the forward voltage Vf with respect to the change in the ambient temperature T. Further, when the forward current If is sequentially increased as I1, I2, and I3 at a constant ambient temperature, for example, T1, the forward voltage Vf is sequentially increased as V1, V2, and V3.

In this embodiment, a forward voltage vs. ambient temperature table indicating the temperature characteristics of the forward voltage for each forward current is stored in the memory 139 in advance as one form of temperature characteristic information. Then, the temperature calculation unit 134 refers to the forward voltage versus ambient temperature table, and for each of the forward currents I1 and I2, the ambient temperature T corresponding to the forward voltages V1 and V2 detected by the A / D 133, respectively. (V1) and T (V2) are specified. If the operation of the endoscope apparatus 10 according to the present embodiment is normal, the specified ambient temperature T (V1) and ambient temperature T (V2) should be equal. Accordingly, the inspecting unit 135 can reliably obtain the obtained ambient temperature T (V1) depending on whether or not the magnitude of the difference between the ambient temperature T (V1) and the ambient temperature T (V2) is within a predetermined range. It can be determined whether or not the temperature is likely.

(Temperature measurement processing)
Next, the temperature measurement process based on the forward voltage will be described. FIG. 4 is a flowchart illustrating an example of the temperature measurement process. The temperature measurement process shown in FIG. 4 is a basic process for displaying the ambient temperature around the LED 112-1 based on the forward voltage generated in the LED 112-1.

(Step S101) The control unit 140 causes the drive circuit 151 to supply a predetermined forward current If to the LED 112-1. The A / D 133 detects the forward voltage Vf generated across the LED 112-1. Thereafter, the process proceeds to step S102.
(Step S102) The temperature calculation unit 134 refers to the forward voltage versus ambient temperature table stored in advance in the memory 139, and specifies the ambient temperature T at the forward voltage Vf under a predetermined forward current If. . Thereafter, the process proceeds to step S103.
(Step S103) The display unit 138 displays the specified ambient temperature T. Thereafter, the process shown in FIG.

(Temperature inspection process)
Next, the temperature inspection process according to the present embodiment will be described. FIG. 5 is a flowchart illustrating an example of the temperature inspection process according to the present embodiment.
(Step S111) The control unit 140 causes the drive circuit 151 to sequentially change the forward current If supplied to the LED 112-1 to I1 and I2. When the forward current If is set to I1 and I2, respectively, the A / D 133 detects the forward voltages V1 and V2 at the respective time points. Thereafter, the process proceeds to step S112.
(Step S112) The temperature calculation unit 134 refers to the forward voltage versus ambient temperature table stored in advance in the memory 139, and the ambient temperature T (V1) in the forward voltage V1 detected for the forward current I1. The ambient temperature T (V2) at the forward voltage V2 detected for the forward current I2 is specified. Thereafter, the process proceeds to step S113.

(Step S113) The inspection unit 135 determines that the absolute value | T (V1) −T (V2) | of the difference between the specified ambient temperature T (V1) and the ambient temperature T (V2) is smaller than a predetermined difference threshold ε. It is determined whether or not. When it is determined that the value is smaller (YES in step S113), the process proceeds to step S114. When it is determined that the difference is equal to or larger than the difference threshold ε (step S113: NO), the process proceeds to step S117.
(Step S114) The inspection unit 135 determines whether or not the specified ambient temperature T (V1) is a temperature within a predetermined usable temperature range. When it is determined that the temperature is within the usable temperature range (YES in step S114), the process proceeds to step S115. When it is determined that the temperature is out of the usable temperature range (NO in step S114), the process proceeds to step S117.

(Step S115) The inspection unit 135 outputs temperature information indicating the ambient temperature T (V1) determined to be within the usable temperature range to the display unit 138. At this time, the display unit 138 displays the ambient temperature T (V1). Thereafter, the process proceeds to step S116.
(Step S116) The control unit 140 determines to continue using the endoscope apparatus 10, that is, to continue temperature measurement, illumination, or imaging. Thereafter, the process shown in FIG.

(Step S117) The inspection unit 135 reads warning information from the memory 139 and outputs the read warning information to the display unit 138. A warning (alarm) is displayed on the display unit 138. Thereafter, the process proceeds to step S118.
(Step S118) The control unit 140 determines to stop using the endoscope apparatus 10. For example, the control unit 140 may stop at least one of temperature measurement, illumination, and imaging. When the temperature measurement is stopped or the lighting is stopped, the control unit 140 transmits a light emission control signal indicating that light emission is not required (OFF) to the drive circuit 151. When stopping the imaging, the control unit 140 outputs to the image processing unit 136 display control signals indicating that display is not necessary (OFF) and recording is not necessary (OFF). Thereafter, the process shown in FIG.

As described above, the endoscope apparatus 10 according to the present embodiment includes at least one LED 112-1 having different electrical characteristics according to temperature and a physical quantity different from the temperature at the distal end of the insertion portion 11, A / D 133 for detecting the characteristic value of the target characteristic is provided. In addition, the endoscope apparatus 10 stores the temperature characteristic information indicating the temperature characteristic of the characteristic value, and the measurement state of the temperature specified by referring to the temperature characteristic information from the characteristic value as the characteristic value for each physical quantity. And an inspection unit 135 for inspecting based on the above.
With this configuration, the measurement state of the temperature specified from the characteristic value of the electrical characteristic of the LED 112-1 is inspected based on the characteristic value of the electrical characteristic that differs for each physical quantity. Therefore, the operation state of the temperature measurement function can be inspected while using the illumination that is the main function of the LED 112-1.

Further, in the endoscope apparatus 10, at least one of the members is an LED 112-1 that emits light in response to supply of a forward current, and the A / D 133 corresponds to supply of forward current as a characteristic value of the LED 112-1. The forward voltage generated is detected. The memory 139 stores a forward voltage vs. ambient temperature table indicating temperature characteristics of the forward voltage generated in response to the forward current supply as temperature characteristic information.
With this configuration, a temperature specified based on different forward voltages for each forward current can be obtained. Therefore, the operation state of the temperature measurement function can be inspected based on each temperature.

Second Embodiment
Next, a second embodiment of the present invention will be described. About the same structure as embodiment mentioned above, the same code | symbol is attached | subjected and the description is used. In the following description, differences from the first embodiment are mainly used.
FIG. 6 is a schematic block diagram showing the configuration of the endoscope apparatus 10A according to the present embodiment. An endoscope apparatus 10A according to the present embodiment is configured to further include an A / D 141 and a temperature calculation unit 142 in the endoscope apparatus 10.

The endoscope apparatus 10A according to the present embodiment detects the temperature based on the forward voltage generated at both ends of the LED 112-2 in addition to the LED 112-1. Therefore, the control unit 140 further generates a current control signal for controlling the forward current supplied to the LED 112-2, and outputs the generated current control signal to the current source 132-2.
The current source 132-2 controls the current value of the current flowing between both ends thereof to be equal to the current value of the forward current indicated by the current control signal input from the control unit 140.

In the present embodiment, the control unit 140 may control the forward current flowing through both ends of the LED 112-1 to be constant by making the forward current indicated by the current control signal to the current source 132-1 constant. . Further, the control unit 140 makes the forward current equal to the forward current indicated by the current control signal to the current source 132-2, so that the forward current flowing through both ends of the LED 112-1 and the both ends of the LED 112-2 are set. It is also possible to control so that the forward current flowing through is equal. Here, the forward current indicated by the current control signal output to the current source 132-1 may be equal to the forward current indicated by the current control signal output to the current source 132-2.

The one end and the other end of the A / D 141 are electrically connected to the one end and the other end of the LED 112-2, respectively. The A / D 141 detects the forward voltage generated at both ends of the LED 112-2, and generates forward voltage data indicating the detected forward voltage V2. The A / D 141 outputs the generated forward voltage data to the temperature calculation unit 142.

The temperature calculation unit 142 reads a forward voltage versus ambient temperature table stored in advance from the memory 139. The temperature calculation unit 142 refers to the read forward voltage vs. ambient temperature table, and calculates the forward current If indicated by the current control signal to the current source 132-2 and the forward voltage data input from the A / D 141. The temperature T (V2) corresponding to the forward voltage V2 shown is specified. This temperature T (V2) corresponds to the ambient temperature of the LED 112-2. The temperature calculation unit 142 outputs temperature data indicating the specified temperature T (V2) to the inspection unit 135.

The inspection unit 135 receives temperature data indicating the temperature T (V1) from the temperature calculation unit 134 and temperature data indicating the temperature T (V2) from the temperature calculation unit 142. The inspection unit 135 determines that the temperature T (V1) is appropriate when the difference | T (V1) −T (V2) | between the temperature T (V1) and the temperature T (V2) is smaller than a predetermined difference threshold ε ′. When the difference | T (V1) −T (V2) | is equal to or greater than a predetermined difference threshold ε ′, it is determined that the temperature T (V1) is inappropriate.

When the inspection unit 135 determines whether or not the temperature T (V1) is appropriate, the inspection unit 135 compares the forward voltage V1 detected by the A / D 133 and the forward voltage V2 detected by the A / D 141. Also good. In the comparison, the inspection unit 135 determines that the temperature T (when the difference | V1−V2 | between the forward voltage V1 and the forward voltage V2 is smaller than a predetermined difference threshold δ (for example, 0.05 to 0.2V). V1) or temperature T (V2) is determined to be appropriate, and when the difference | V1-V2 | is equal to or greater than a predetermined difference threshold δ, it is determined to be inappropriate. In this determination, the conversion from the forward voltages V1 and V2 to the temperatures T (V1) and T (V2) is not necessarily performed. This means that the temperature calculation unit 142 may be omitted in the endoscope apparatus 10A according to the present embodiment.

(Temperature inspection process)
Next, the temperature inspection process according to the present embodiment will be described. FIG. 7 is a flowchart illustrating an example of the temperature inspection process according to the present embodiment. The temperature inspection process according to the present embodiment includes processes of steps S121 to S123 and processes of steps S114 to S118. The processing in steps S114 to S118 is common to the temperature inspection processing shown in FIG.

(Step S121) The control unit 140 sets the common forward current I1 as the forward current If supplied to the LEDs 112-1 and 112-2 for the current sources 132-1 and 132-2. A / D 133 and A / D 141 detect forward voltages V1 and V2, respectively. Thereafter, the process proceeds to step S122.
(Step S122) The inspection unit 135 determines whether or not the absolute value | V1−V2 | of the difference between the detected forward voltages V1 and V2 is smaller than a predetermined difference threshold δ. When it is determined that the value is smaller (YES in step S122), the process proceeds to step S123. When it is determined that the difference is equal to or greater than the threshold value δ (NO in step S122), the process proceeds to step S117.
(Step S123) The temperature calculation unit 134 refers to the forward voltage vs. ambient temperature table stored in advance in the memory 139 and specifies the ambient temperature T (V1) in the forward voltage V1 detected for the forward current I1. To do. Thereafter, the process proceeds to step S114.

<Modification>
In the above description, the inspection unit 135 compares the forward voltages V1 and V2 at that time or compares the ambient temperatures T (V1) and T (V2) to determine whether the ambient temperature T (V1) is appropriate. However, the present invention is not limited to this. In the modification according to the present embodiment, the inspection unit 135 determines the forward voltage V1 (t) at the time t from the forward voltages V1 (t ₀ ) and V2 (t ₀ ) at the temperature measurement start time t ₀ . , V2 (t) and ΔV1 (t) and ΔV2 (t) may be compared with each other. Here, the amount of change ΔV1 (t), ΔV2 (t ) , respectively _{V1 (t) -V1 (t 0} ), a _{V2 (t) -V2 (t 0} ).

In the comparison, the inspecting unit 135 first determines which of the three levels of change ΔV1 (t) and ΔV2 (t) is −γ or less, a value greater than −γ and smaller than γ, or γ or more. It is determined whether it belongs to the stage. γ is a predetermined threshold value for determining whether or not the variation amounts ΔV1 (t) and ΔV2 (t) are significantly different from zero. γ is, for example, 0.05 to 0.2V. That is, this three-stage determination is a determination of whether the change amounts ΔV1 (t) and ΔV2 (t) are significantly positive, substantially 0, and significantly negative, respectively.
The inspecting unit 135 determines that the ambient temperature T (V1) is appropriate when both the changes ΔV1 (t) and ΔV2 (t) are significantly positive, substantially 0, and significantly negative. Judge that there is. When the determination is different between the change amounts ΔV1 (t) and ΔV2 (t), for example, the inspection unit 135 has a significantly positive change amount ΔV1 (t) and a significant change amount ΔV2 (t). When it is negative, it is determined that the ambient temperature T (V1) is inappropriate. Therefore, in this determination, since it is determined whether or not the change tendency of the forward voltage V1 and the change tendency of the forward voltage V2 are common, it is easy to determine whether or not the ambient temperature T (V1) is appropriate. Is determined. In this determination, the forward current does not necessarily have to be equal between the LEDs 112-1 and 112-2. When the forward current is controlled independently, the brightness of the light emitted between the LEDs 112-1 and 112-2 is allowed to be different.

Note that this determination may be performed for the ambient temperatures T (V1) and T (V2) instead of the forward voltages V1 and V2. However, the inspection unit 135 determines that the variations ΔT (V1 (t)) and ΔT (V2 (t)) of the ambient temperatures T (V1) and T (V2) are significantly positive, substantially 0, and significantly When determining whether it is negative, a predetermined threshold ι is used instead of the threshold γ. ι is, for example, 0.1 ° C to 0.3 ° C.

In addition, the inspection unit 135 calculates a time-series correlation coefficient ρ from the temperature measurement start time t ₀ to the time t at the time point of the change amounts ΔV 1 (t) and ΔV 2 (t) of the forward voltages V 1 and V 2. May be. When the correlation coefficient ρ is larger than the predetermined correlation coefficient threshold ρ ′, the inspection unit 135 determines that the ambient temperature T (V1) is appropriate, and the correlation coefficient ρ is the predetermined correlation coefficient threshold. When it is equal to or lower than ρ ′, it may be determined that the ambient temperature T (V1) is inappropriate. The threshold value ρ ′ is, for example, 0.9. This determination may also be applied to the ambient temperatures T (V1) and T (V2) instead of the forward voltages V1 and V2.

As described above, the endoscope apparatus 10A according to the present embodiment includes a plurality of LEDs 112-1 and 112-2 having different forward voltages depending on the temperature at the distal end of the insertion portion 11. In addition, the endoscope apparatus 10A includes A / D 133 and 144 for detecting the characteristic value of the electrical characteristic for each of the LEDs 112-1 and 112-2, and a memory 139 for storing temperature characteristic information indicating the temperature characteristic of the characteristic value. Prepare. Further, the endoscope apparatus 10A refers to the temperature characteristic information, and inspects the measurement state of the temperature specified from the characteristic value based on the comparison of the characteristic values of the LEDs 112-1 and 112-2. Is provided.
With this configuration, the measurement state of the temperature specified from the characteristic values of the electrical characteristics of the LEDs 112-1 and 112-2 is inspected based on the respective characteristic values or temperatures. Therefore, it is possible to inspect the operation state of the temperature measurement function while using the illumination that is the main function of the LEDs 112-1 and 112-2.

In addition, the inspection unit 135 calculates the amount of change in temperature or characteristic value from the start of temperature measurement for each of the LEDs 112-1 and 112-2, and calculates the temperature based on the amount of change for each of the LEDs 112-1 and 112-2. Check the measurement status.
With this configuration, when the temperatures are not completely equal between the LEDs 112-1 and 112-2, or as a physical quantity other than the temperature that changes the characteristic value, for example, even when the forward current is not common, the temperature measurement state Can be inspected.

<Third Embodiment>
Next, a third embodiment of the present invention will be described. About the same structure as embodiment mentioned above, the same code | symbol is attached | subjected and the description is used. In the following description, differences from the first embodiment are mainly used.
FIG. 8 is a schematic block diagram showing the configuration of the endoscope apparatus 10B according to the present embodiment. The endoscope apparatus 10B according to the present embodiment is configured to further include a temperature calculation unit 137 in the endoscope apparatus 10.

The image processing unit 136 selects an output signal for each pixel in an optical black (OB) area from among the output signals for each pixel input from the signal driver 114. The OB region is a predetermined region that is shielded without being irradiated with incident light transmitted through the lens 111 among pixel regions in which pixels of the image sensor 113 are arranged. Charge accumulation in each pixel is mainly caused by photoelectric conversion with respect to incident light, but is also caused by thermal noise in pixels arranged in an OB region that is not irradiated with incident light. In other words, the signal value of the output signal for each selected pixel represents the amount of accumulated charge due to thermal noise.

For the signal value indicated by the selected output signal, the image processing unit 136 calculates, for each pixel, a difference value between the signal value of the current frame (current frame) and the signal value of the immediately preceding frame (previous frame), for example. . Then, the image processing unit 136 calculates the dark current value _ID in the current frame based on the distribution of the calculated difference values between the pixels. The image processing unit 136 outputs the calculated dark current value _ID to the temperature calculation unit 137. An example of the dark current calculation process will be described later.

The temperature calculation unit 137 calculates the temperature T2 of the image sensor 113 based on the dark current value _ID input from the image processing unit 136. In general, a larger dark current value _ID indicates a higher temperature T2. The temperature calculation unit 137 may calculate the temperature T2 using a relationship shown in a mathematical expression described later, or refers to a dark current temperature table stored in advance in the memory 139 and corresponds to the dark current value _ID. T2 may be specified. The dark current temperature table is data indicating the temperature dependence of the dark current value _ID as dark current temperature characteristic information. The temperature calculation unit 137 outputs temperature data indicating the calculated temperature T2 to the inspection unit 135.

The inspection unit 135 receives temperature data indicating the temperature T (V1) from the temperature calculation unit 134 and temperature data indicating the temperature T2 from the temperature calculation unit 137. The inspection unit 135 determines that the temperature T (V1) is appropriate when the difference | T (V1) −T2 | between the temperature T (V1) and the temperature T2 is smaller than a predetermined difference threshold ε, and the difference | T When (V1) −T2 | is equal to or greater than a predetermined difference threshold ε, it is determined that the temperature T (V1) is inappropriate.

(OB area)
Next, an example of the OB area will be described. FIG. 9 is a conceptual diagram illustrating an example of an output signal input from the signal driver 114 according to the present embodiment. FIG. 9 shows that output signals are sequentially acquired for each frame at a predetermined frame rate α [fps]. In FIG. 9, the output signals of the frames (0) to (n) are represented by rectangles. Also, among the output signals of each frame, the upper left filled area indicates the output signal from the pixel arranged in the OB area, and the other area indicates the output signal from the pixel arranged in the imaging area. . In the OB region, incident light transmitted through the lens 111 is always shielded by the arrangement of the image sensor 113. A dark current value _ID obtained from an output signal from a pixel arranged in the OB region is used for temperature measurement. On the other hand, an output signal from a pixel arranged in an imaging region irradiated with incident light is used for generating an image signal in the image processing unit 136.

(Temperature dependence of dark current accumulated charge)
Next, the dark current accumulated charge amount in the photodiode constituting each pixel of the image sensor 113 will be described. FIG. 10 is a diagram illustrating an example of the dark current accumulated charge amount. The vertical axis and the horizontal axis indicate the dark current accumulated charge amount Q and the accumulation time τ, respectively. The dark current accumulated charge amount Q is substantially proportional to the accumulation time τ. The dark current accumulated charge amount Q and the accumulation time τ have the relationship shown in the equation (1).

Q = k · τ (1)

In Equation (1), k represents a proportional coefficient. The proportionality coefficient k depends on the temperature. Generally, the higher the temperature, the larger the proportional coefficient k. This means that the dark current increases as the temperature increases. FIG. 10 shows that the dark current increases in the order of increasing temperature T _A , T _B , T _C and temperature. The accumulation time τ is the elapsed time from the start of charge accumulation. That is, the accumulation time τ corresponds to the exposure time or the frame period (reciprocal of the frame rate).

(Temperature dependence of dark current)
Next, dark current generated in the photodiode will be described. FIG. 11 is a diagram illustrating an example of temperature dependence of dark current generated in a photodiode. The vertical axis and the horizontal axis indicate the dark current value I _D and the temperature T, respectively. The dark current value _ID increases exponentially as the temperature T increases. The dark current value _ID and the temperature T have the relationship shown in Formula (2).

I _D = s · ^{er · T} (2)

In Equation (2), s and r are coefficients depending on the image sensor 113, such as the material, size, and shape of the photodiode. Equation (2) is transformed as shown in Equation (3).

T = (1 / r) · ln ( _ID / s) (3)

Therefore, Equation (3) indicates that the temperature T can be calculated from the acquired dark current value _ID . Therefore, a dark current temperature table representing the relationship between the dark current value represented by the equation (3) and the temperature is set in the memory 139. The temperature calculation unit 137 obtains a temperature T corresponding to the dark current value _ID input from the image processing unit 136 with reference to the dark current temperature table. Note that the temperature calculation unit 137 may calculate the temperature T from the dark current value _ID using the relationship shown in Equation (3) without using the dark current temperature table. In that case, the coefficients s and r are set in the temperature calculation unit 137 in advance.

(Dark current calculation process)
Next, the dark current calculation process according to the present embodiment will be described. The image processing unit 136 calculates the difference value _{V CAL} is a difference between the signal value _{V OUT} of the previous frame from the signal value _{V OUT} of the current frame for each pixel in the OB region.
The image processing unit 136 aggregates the difference values V _CAL calculated for each pixel in the OB area between the pixels, and determines a frequency-to-pixel distribution for each difference value V _CAL . The image processing unit 136 determines the noise level N _CAL of the difference value V _CAL from the determined inter-pixel distribution. Then, the image processing unit 136 calculates the dark current value _ID using the relationship shown in Expression (4) for the noise level N _CAL calculated by the image processing unit 136 and the preset read noise level N _RO . The readout noise level _NRO is a level of readout noise mixed in the output signal read from the pixel.

I _D = α · (N _CAL ² / 2-N _RO ² ) (4)

Equation (4) is the dark current value I _D is the dark current accumulation charge quantity Q _DC per frame obtained by subtracting the square of half the reading from the value the noise level N _RO of the square of the noise level N _CAL, frame rate α It is calculated by multiplying by.
Equation (4) is derived based on the relationships shown in equations (5) and (6).

N _CAL = √2 · N _OUT (5)
N _OUT = √ (N _DC ² + N _RO ² ) (6)

In Expression (5), N _OUT indicates the noise level of the signal value V _OUT of each frame. Expression (5) indicates that the noise of the signal value _VOUT that is generated at random in each pixel and whose average value for each frame is substantially equal between the frames is added to obtain the noise of the difference value _VCAL . Even if the signal value is subtracted between frames in the process of calculating the difference value V _CAL , the noise component is not canceled out. The noise level N _CAL of the difference value V _CAL is √2 times the noise level N _OUT of each frame. In Equation (6), N _DC represents the noise level of dark current shot noise in the photodiodes constituting each pixel. Equation (6) is obtained by adding the dark current shot noise randomly generated in each pixel and the readout noise to obtain the noise of the signal value _VOUT . The square value N _DC ² of the dark current shot noise level corresponds to the dark current accumulated charge amount Q _DC .

Accordingly, in the difference value V _CAL obtained from the difference between the signal values V _OUT between frames, the noise level N _CAL obtained without canceling out the noise component is used for the calculation of the dark current value _ID . On the other hand, by calculating the difference of the signal value V _OUT between frames, a common noise component between frames such as a fixed pattern noise (FPN) component included in the output signal is canceled.

(Noise level determination processing)
Next, the noise level determination process will be described. When determining the noise level N _CAL , the image processing unit 136 obtains the inter-pixel distribution of the difference value V _CAL . The inter-pixel distribution of the difference value is represented by the frequency (that is, the number of pixels) for each signal value (or a section composed of a plurality of adjacent signal values) as shown in FIG. Then, the image processing unit 136 calculates the standard deviation σ between the pixels of the signal value as the noise level N _CAL .

Next, a process in which the image processing unit 136 determines the read noise level _NRO will be described. The image sensor 113 includes a readout circuit (not shown) for reading out an output signal for each pixel. The readout circuit includes a photodiode, a pixel amplifier, and a post-amplifier for each pixel. The photodiode is a light receiving element that generates an electrical signal by photoelectric conversion. The pixel amplifier amplifies the output signal from the photodiode and outputs it to the post-amplifier and signal driver 114. The readout noise is added to the output signal for each pixel mainly between the pixel amplifier and the signal driver 114, but it is difficult to extract from the noise of the signal value _VOUT .

Therefore, the image processing unit 136 obtains the inter-pixel distribution of the signal value of the amplified signal from the post-amplifier, and calculates the standard deviation of the obtained signal value as the noise level N _RO of the read noise. The post-amplifier is configured to include an amplification circuit with a variable amplification factor function, and a sufficiently large amplification factor (for example, a maximum amplification factor in the specification) is set in advance. While the noise added to the output signal from the pixel amplifier is amplified, the readout noise is not amplified by the post-amplifier and is sufficiently smaller than the noise added to the output signal. Therefore, the read noise and the noise added to the output signal from the pixel amplifier can be discriminated by their levels. Accordingly, the image processing unit 136, can be determined with a standard deviation of the distribution of the signal values between the pixels indicated by the amplified signal from the post-amplifier noise level N _RO readout noise.

The image processing unit 136 calculates the noise level N _CAL based on the difference value V _CAL for each frame, but the noise level N _RO of the readout noise does not necessarily have to be calculated for each frame. The image processing unit 136 may acquire a noise level _NRO of readout noise based on the amplified signal in advance before capturing an image. The acquisition timing may be, for example, any of a test operation, a parameter setting, and the like. Normally the operating environment (e.g., usable temperature -10 ° C ~ 70 ° C) Under Because so little variation in the noise level N _RO is negligible, the noise level N _RO is continued as it was once set May be used.

(Temperature inspection process)
Next, the temperature inspection process according to the present embodiment will be described. FIG. 13 is a flowchart illustrating an example of a temperature inspection process according to the present embodiment. The temperature inspection process according to the present embodiment includes the processes of steps S131 to S136 and the processes of steps S114 to S118. The processing in steps S114 to S118 is common to the temperature inspection processing shown in FIG.

(Step S131) The control unit 140 sets the forward current If supplied to the LED 112-1 for the current source 132-1. The A / D 133 detects the forward voltage V1. Thereafter, the process proceeds to step S132.
(Step S132) The temperature calculation unit 134 refers to the forward voltage versus ambient temperature table stored in advance in the memory 139, and identifies the ambient temperature T (V1) in the forward voltage V1 detected for the forward current If. To do. Thereafter, the process proceeds to step S133.

(Step S133) The image processing unit 136 calculates an inter-frame difference value V _CAL for the signal value indicated by the output signal for each pixel in the OB area among the output signals for each pixel. The image processing unit 136 calculates a standard deviation indicating the magnitude of the calculated inter-pixel distribution of the difference value V _CAL as the noise level N _CAL . Thereafter, the process proceeds to step S134.
(Step S134) The image processing unit 136 calculates the dark current value _ID based on the noise level N _CAL , the preset read noise level N _RO and a predetermined frame rate α. Thereafter, the process proceeds to step S135.
(Step S135) The temperature calculation unit 137 calculates the ambient temperature T2 of the image sensor 113 based on the dark current value _ID . Thereafter, the process proceeds to step S136.

(Step S136) The inspection unit 135 determines whether or not the absolute value | T (V1) −T2 | of the difference between the specified ambient temperature T (V1) and the calculated ambient temperature T2 is smaller than a predetermined difference threshold ε. judge. When it is determined that it is small (YES in step S136), the process proceeds to step S114. When it is determined that the difference is equal to or larger than the difference threshold ε (NO in step S136), the process proceeds to step S117.

<Modification>
Next, a modification of this embodiment will be described. As shown in FIG. 14, an endoscope apparatus 10C according to this modification further includes a light guide 115 and a temperature calculation unit 143 in the endoscope apparatus 10B. The light guide 115 is disposed between the LED 112-1 provided at the distal end portion of the insertion portion 11 and the image sensor 113. The light guide 115 is a member that transmits a part of the light emitted from the LED 112-1 to the image sensor 113. The light that has passed through the light guide 115 is applied to a predetermined area of the pixel area in which the pixels of the image sensor 113 are arranged. In the following description, an area irradiated with light transmitted through the light guide 115 is referred to as an irradiation area. The irradiation area is a part of the non-imaging area excluding the imaging area in which the image of the subject is captured in the pixel area. The other part of the non-imaging area corresponds to the OB area described above.

In the present modification, the image processing unit 136 detects the relative luminance of the light emitted by the LED 112-1 based on the signal value indicated by the output signal for each pixel in the irradiation region among the output signals for each pixel. That is, the photodiode constituting each pixel in the irradiation area is used as a luminance sensor. The photodiode generates an output signal having a voltage value corresponding to the intensity of light from the LED 112-1 as a signal value. In the example shown in FIG. 15, the relative luminance is the ratio of the luminance at that time with reference to the luminance when the ambient temperature is 25 ° C. at the start of use of the LED 112-1. Therefore, the luminance of the light arriving at the irradiation area from the LED 112-1 does not necessarily have to be equal to the luminance of the light emitted from the tip of the insertion portion 11, and may be attenuated from the luminance. The image processing unit 136 outputs luminance information indicating the detected relative luminance to the temperature calculation unit 143. The memory 139 further stores a luminance vs. ambient temperature table in advance as luminance temperature information. The luminance vs. ambient temperature table is data indicating the temperature characteristics of the luminance of the LED 112-1 for each forward current.

The temperature calculation unit 143 refers to the luminance vs. ambient temperature table stored in the memory 139 and obtains the forward current indicated by the current control signal to the current source 132-1 and the luminance information input from the image processing unit 136. The temperature T2 ′ corresponding to the indicated relative luminance is specified. The temperature calculation unit 143 outputs temperature data indicating the specified temperature T2 ′ to the inspection unit 135.
The inspection unit 135 receives temperature data indicating the temperature T2. In the inspection unit 135, the difference | T (V1) −T2 ′ | between the temperature T (V1) specified by the temperature calculation unit 134 and the temperature T2 ′ specified by the temperature calculation unit 143 is smaller than a threshold ε of a predetermined difference. Temperature T (V1) is determined to be appropriate, and temperature T (V1) is determined to be inappropriate when the difference | T (V1) −T2 ′ |

As shown in FIG. 15, under the constant forward current, the relative luminance of the light emitted from the LED 112-1 decreases as the ambient temperature T increases. If the LED 112-1 continues to be exposed to a high temperature environment for a long time, the luminance decreases, and the luminance at the beginning of use cannot be maintained. This causes the temperature T2 'specified based on the forward current and the brightness indicated by the brightness information with reference to the brightness vs. ambient temperature table in the temperature calculation unit 143 to be higher than the actual temperature. Therefore, the inspection unit 135 can determine whether or not these temperatures are appropriate based on the difference | T (V1) −T2 ′ | between the temperature T (V1) and the temperature T2 ′.

(Temperature inspection process)
Next, a temperature inspection process according to this modification will be described. FIG. 16 is a flowchart illustrating an example of a temperature inspection process according to the present modification. The temperature inspection process according to the present embodiment includes processes of steps S131, S132, S136, S143, and step S144, and processes of steps S114 to S118. Since the processes in steps S131, S132 and S136 and the processes in steps S114 to S118 are common to the temperature inspection process shown in FIG. 13, the description thereof is omitted.

In the process illustrated in FIG. 16, the process proceeds to step S143 after the processes in step S131 and step S132.
(Step S143) The image processing unit 136 detects (measures) the relative luminance of the light emitted by the LED 112-1 based on the signal value indicated by the output signal for each pixel in the irradiation region of the image sensor 113. Thereafter, the process proceeds to step S144.
(Step S144) The temperature calculation unit 143 refers to the luminance versus ambient temperature table stored in the memory 139, and the forward current indicated by the current control signal to the current source 132-1 and the image processing unit 136 detect A temperature T2 ′ corresponding to the relative luminance is specified. Thereafter, the process proceeds to step S136.

In this modification, in step S136, the inspection unit 135 determines that the difference | T (V1) −T2 ′ | between the temperature T (V1) specified by the temperature calculation unit 134 and the temperature T2 ′ specified by the temperature calculation unit 143 is It is determined that the temperature T (V1) or the temperature T2 ′ is appropriate when it is smaller than the predetermined difference threshold ε, and is inappropriate when the difference | T (V1) −T2 ′ | is equal to or greater than the predetermined difference threshold ε. judge.

Note that, in the endoscope apparatus 10 according to the modification described above, even if the temperature calculation unit 137 for specifying the temperature T2 based on the dark current value _ID calculated by the image processing unit 136 is omitted as illustrated in FIG. Alternatively, the temperature calculation unit 137 may be provided. When the temperature calculation unit 137 is provided in the endoscope apparatus 10, the inspection unit 135 determines a difference | T () between the temperature T (V1) specified by the temperature calculation unit 134 and the temperature T2 specified by the temperature calculation unit 143. V1) −T2 | is greater than or equal to a predetermined difference threshold ε, or the difference | T (V1) −T2 ′ between the temperature T (V1) specified by the temperature calculation unit 134 and the temperature T2 ′ specified by the temperature calculation unit 137 When | is equal to or greater than a predetermined difference threshold ε, the temperature T (V1) specified by the temperature calculation unit 134 is determined to be inappropriate.

As described above, in the endoscope apparatus 10B according to the present embodiment, the other member having different electrical characteristics depending on the temperature is the image sensor 113 that photoelectrically converts the incoming light. Further, the image processing unit 136 detects a dark current generated in the image sensor 113 as a characteristic value of the electrical characteristics of the image sensor 113. Further, the memory 139 further stores a dark current temperature table indicating the temperature characteristics of dark current as temperature characteristic information.
With this configuration, the temperature measurement state based on the forward voltage generated in the LED 112-1 is inspected based on the temperature based on the dark current generated in the image sensor 113. Therefore, it is possible to inspect the operation state of the temperature measurement function while using the illumination that is the main function of the LED 112-1 and the imaging that is the main function of the image sensor 113.

In addition, the endoscope apparatus 10C includes an image processing unit 136 that detects the luminance of light from the LED 112-1. In addition, the memory 139 stores a luminance vs. ambient temperature table indicating the temperature characteristics of the luminance of light emitted in response to the forward current supply. The inspection unit 135 compares the temperature specified from the luminance detected with reference to the luminance vs. ambient temperature table and the temperature specified from the forward voltage with reference to the forward voltage vs. ambient temperature table. Check the measurement state.
With this configuration, the temperature measurement state based on the forward voltage generated in the LED 112-1 is inspected based on the temperature based on the brightness detected by the image processing unit 136. Therefore, it is possible to inspect the operating state of the temperature measurement function due to a decrease in luminance of the LED 112-1 due to long-term use in a high temperature environment or aging deterioration.

As mentioned above, although embodiment and the modification of this invention were demonstrated, in the range which does not deviate from the summary of this invention, a various deformation | transformation can be added.
For example, the number of LEDs included in the endoscope apparatuses 10, 10A, 10B, and 10C is not limited to two, and may be three or more. In that case, the inspection unit 135 determines whether or not the temperature calculated by comparing the forward voltages generated at both ends of each LED or the temperatures calculated based on each forward voltage is appropriate. Also good.
Note that the modification described in the second embodiment may be applied to the endoscope apparatus 10 according to the first embodiment or the endoscope apparatuses 10B and 10C according to the third embodiment. The modification described in the third embodiment may be applied to the endoscope apparatus 10 according to the first embodiment or the endoscope apparatus 10A according to the second embodiment.
Further, in the endoscope apparatuses 10, 10B, 10C, the LED 112-2 and the current source 132-2 may be omitted.

In the first embodiment described above, the LED 112 is mainly a member that is provided at the distal end of the insertion portion 11 of the endoscope apparatus 10 and has different electrical characteristics according to a physical quantity separate from the temperature. The case where the physical quantity is the forward current and the electrical characteristic is the forward voltage is taken as an example. In the second embodiment, the case where the member that is provided at the distal end of the insertion portion 11 of the endoscope apparatus 10A and has different electrical characteristics depending on the temperature is the LED 112, and the electrical characteristics are forward voltages. Take an example. In the third embodiment, the LED 112 and the image sensor 113 that are provided at the distal ends of the insertion portions 11 of the endoscope apparatuses 10B and 10C and have different electrical characteristics depending on the temperature are the LEDs 112 and the electric elements of the LED 112. An example is given in which the characteristic is a forward voltage and the electrical characteristic of the image sensor 113 is a dark current.
These members may be other types of members, for example, passive elements such as a resistance element, a capacitor, and a coil. The physical quantity separate from the temperature may be a passive element such as an electric resistance, an electric capacity, and an inductance. The electrical characteristic may be a voltage across the member.

A part of the endoscope apparatuses 10, 10A, 10B, and 10C, for example, the temperature calculation units 134, 137, 142, and 143, the inspection unit 135, the image processing unit 136, and the control unit 140 may be realized by 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 apparatuses 10, 10A, 10B, and 10C, and includes hardware such as an OS and 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, it may include a volatile memory inside a computer system serving as a server or a client, which 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.

Further, a part or all of the endoscope apparatuses 10, 10A, 10B, and 10C in 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 10 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.

According to the endoscope apparatus and the temperature measurement method of each aspect described above, the measurement state of the temperature specified from the characteristic values of the electrical characteristics of the members having different electrical characteristics according to the physical quantities other than the temperature and the temperature is determined for each physical quantity. Inspected based on characteristic values or temperatures of different electrical characteristics. Alternatively, the measurement state of the temperature specified from the characteristic values of the members having different electrical characteristics depending on the temperature is inspected based on the respective characteristic values or temperatures. Therefore, the operating state of the temperature measurement function can be inspected while using the main functions of each member.

DESCRIPTION OF SYMBOLS 10, 10A, 10B, 10C ... Endoscope apparatus, 11 ... Insertion part, 12 ... Housing, 111 ... Lens, 112 (112-1, 112-2) ... LED, 113 ... Imaging element, 114 ... Signal driver, 115: Light guide, 132 (132-1, 132-2) ... Current source, 133, 141 ... A / D, 134, 137, 142, 143 ... Temperature calculation unit, 135 ... Inspection unit, 136 ... Image processing unit, 138: Display unit, 139 ... Memory, 140 ... Control unit, 151 ... Drive circuit, 152 ... Power source, 153 ... Variable resistance element

Claims (8)

1. A member having different electrical characteristics according to temperature and a physical quantity distinct from the temperature is provided at the tip of the insertion portion,
   A detector for detecting a characteristic value of the electrical characteristic;
   A storage unit for storing temperature characteristic information indicating a temperature characteristic of the characteristic value;
   An inspection unit that inspects the measurement state of the temperature specified by referring to the temperature characteristic information from the characteristic value based on the characteristic value for each physical quantity;
   An endoscope apparatus comprising:
2. Equipped with a plurality of members with different electrical characteristics at the tip of the insertion section depending on the temperature,
   A detection unit for detecting a characteristic value of the electrical characteristic for each member;
   A storage unit for storing temperature characteristic information indicating a temperature characteristic of the characteristic value;
   With reference to the temperature characteristic information, an inspection unit that inspects the measurement state of the temperature specified from the characteristic value based on the comparison of the characteristic value for each member;
   An endoscope apparatus comprising:
3. The endoscope apparatus according to claim 2, wherein the inspection unit calculates an amount of change from the start of measurement of the temperature for each member, and inspects the measurement state based on the amount of change for each member.
4. At least one of the members is a light emitting element that emits light in response to current supply,
   The detection unit detects a voltage generated according to the supply of the current as the characteristic value of the light emitting element,
   The endoscope apparatus according to any one of claims 1 to 3, wherein the storage unit stores information indicating a temperature characteristic of a voltage generated according to the supply of the current as the temperature characteristic information.
5. A luminance detector for detecting the luminance of light from the light emitting element;
   The storage unit stores luminance temperature characteristic information indicating a temperature characteristic of luminance of light emitted according to the supply of the current,
   The inspection unit inspects the measurement state of the temperature by comparing the temperature specified from the luminance with reference to the luminance temperature characteristic information and the temperature specified from the voltage with reference to the temperature characteristic information. The endoscope apparatus according to claim 4.
6. Another one of the members is an image sensor that photoelectrically converts incoming light,
   The detection unit detects a dark current generated in the image sensor as the characteristic value of the image sensor,
   The endoscope apparatus according to any one of claims 2 to 5, wherein the storage unit further stores dark current temperature characteristic information indicating a temperature characteristic of the dark current as the temperature characteristic information.
7. A temperature inspection method for an endoscope apparatus,
   A detection step of detecting a characteristic value of the electrical characteristic of a member provided at the distal end of the insertion portion and having a different electrical characteristic in accordance with a temperature and a physical quantity separate from the temperature;
   The temperature measurement state specified from the characteristic value detected in the detection step with reference to the temperature characteristic information stored in the storage unit and indicating the temperature characteristic of the characteristic value is inspected based on the characteristic value for each physical quantity. An inspection step to perform,
   A temperature inspection method.
8. A temperature inspection method for an endoscope apparatus,
   A detection step of detecting a characteristic value of each of the electrical characteristics of each of the members provided in a plurality at the distal end of the insertion portion and having different electrical characteristics depending on the temperature;
   An inspection for inspecting the measurement state of the temperature specified from the characteristic value based on the comparison of the characteristic value for each member with reference to temperature characteristic information stored in the storage unit and indicating the temperature characteristic of the characteristic value Steps,
   A temperature inspection method.

Images