Endoscope and endoscope apparatus
An endoscope includes a sensor, and a temperature compensation circuit configured to perform temperature compensation of an output signal of the sensor, in a distal end portion. The temperature compensation circuit includes a differential amplifying section configured to amplify an output signal of the sensor, and a temperature sensing section in which a resistance is connected in series to a parallel connection portion of a temperature sensing element and a resistance.
1. An endoscope comprising:
an insertion portion;
a sensor arranged in a distal end portion of the insertion portion; and
a temperature compensation circuit configured to perform temperature compensation of an output signal of the sensor, arranged in the distal end portion of the insertion portion,
wherein the temperature compensation circuit comprises:
an operational amplifier configured to amplify an output signal of the sensor; and
a temperature sensing section comprising:
a temperature sensing element and a first resistance connected in a parallel connection; and
a second resistance connected in series to the parallel connection of the temperature sensing element and the first resistance.
2. The endoscope according to claim 1 ,
wherein the operational amplifier is connected to an input portion of an amplifier, and
wherein the amplifier comprises the temperature sensing section.
3. The endoscope according to claim 2 ,
wherein an amplification factor of the operational amplifier is larger than an amplification factor of the amplifier.
4. The endoscope according to claim 1 ,
wherein a combined resistance of the temperature sensing element and the first resistance changes in accordance with a temperature,
wherein the second resistance is configured to adjust a change amount of the combined resistance to the temperature, and
wherein the change amount is set so that a sum of:
a temperature coefficient of a conversion ratio from a detected physical quantity of the sensor to a voltage; and
a temperature coefficient of a differential amplification factor by temperature dependency of the sensor, decreases.
5. The endoscope according to claim 1 , further comprising: a magnet wherein the sensor comprises a magnetoresistive element, wherein a combined resistance of the temperature sensing element and the first resistance changes in accordance with a temperature, wherein the second resistance is configured to adjust a change amount of the combined resistance to the temperature, and wherein the change amount is set so that a sum of: a temperature coefficient of a magnetic flux density of the magnet, a temperature coefficient of a conversion rate from a magnetic flux density of the magnetoresistive element to a voltage; and a temperature coefficient of a differential amplification factor by temperature dependency of an output resistance of the magnetoresistive element, decreases.
6. The endoscope according to claim 1 ,
wherein the temperature sensing element comprises a chip type negative temperature coefficient thermistor having a negative temperature coefficient.
7. An endoscope apparatus comprising:
the endoscope according to claim 1 ; and
a processor,
wherein the endoscope comprises:
a cable; and
a connector configured to be detachably connected to the processor, and
wherein the processor is configured to:
generate a reference voltage that is supplied to the operational amplifier; and
transmit the reference voltage through the connector and the cable.
8. An endoscope apparatus comprising:
the endoscope according to claim 1 ; and
a processor,
wherein the endoscope comprises:
a cable; and
a connector configured to be detachably connected to the processor, and
wherein the connector is configured to:
generate a reference voltage that is supplied to the operational amplifier; and
transmit the reference voltage through the cable.