Measurement circuit, driving method, and electronic instrument

Patent metadata

Field	Value
Publication number	US-11464416-B2
Application number	US-201716083323-A
Country	US
Kind code	B2
Filing date	Mar 3, 2017
Priority date	Mar 17, 2016
Publication date	Oct 11, 2022
Grant date	Oct 11, 2022

Abstract

The present technology relates to a measurement circuit, a driving method, and an electronic instrument capable of reducing power consumption. In the measurement circuit, irradiation light is emitted from the light emitting unit toward the object, and light from the object is received to measure pulse waves or the like. The measurement circuit includes: a light receiving unit that receives light from an object; an integrating unit that performs integration of a current generated in accordance with the reception of the light by the light receiving unit and generates a voltage according to the amount of reception of the light; and a pulse generating unit that generates a pulse signal having a pulse width corresponding to the amount of reception of the light on the basis of the voltage. The present technology can be applied to electronic instruments such as wearable devices, for example.

First claim

The invention claimed is:

1. A measurement circuit, comprising:
circuitry configured to:
control a first light emitting diode (LED) to start emission of first light at a start of a first light emission period, wherein the first light is emitted towards an object;
receive the first light reflected by the object;
generate a first current based on the received first light;
execute integration of the generated first current in the first light emission period, wherein the integration of the generated first current is completed before an end of the first light emission period;
control the first LED to stop the emission of the first light at the end of the first light emission period;
generate a first voltage based on the integration of the generated first current;
generate a first pulse signal having a pulse width based on the generated first voltage;
control a second light emitting diode (LED) to start emission of second light at a start of a second light emission period, wherein
the second light is emitted towards the object, and
the second light emission period is different from the first light emission period;

receive the second light reflected by the object;
generate a second current based on the received second light;
execute integration of the generated second current in the second light emission period, wherein the integration of the generated second current is completed before an end of the second light emission period;
control the second LED to stop the emission of the second light at the end of the second light emission period;
generate a second voltage based on the integration of the generated second current;
generate a second pulse signal having a pulse width based on the generated second voltage;

control a counter to:
measure a first number of clocks in a first pulse width period of the first pulse signal, wherein
the counter is stopped during the first light emission period, and
the measurement of the first number of clocks is executed after the end of the first light emission period and before a start of the second light emission period; and

measure a second number of clocks in a second pulse width period of the second pulse signal, wherein
the counter is stopped during the second light emission period, and
the measurement of the second number of clocks is executed after the end of the second light emission period; and

generate digital measurement data based on the measured first number of clocks and the measured second number of clocks.

2. The measurement circuit according to claim 1 , wherein the circuitry is further configured to generate the first pulse signal after the end of the first light emission period.

3. The measurement circuit according to claim 1 , further comprising a capacitor configured to accumulate electric charges based on the generated first current, wherein
the circuitry is further configured to execute the integration of the generated first current based on the accumulated electric charges in the capacitor.

4. The measurement circuit according to claim 3 , further comprising an amplifier, wherein
the capacitor is connected between an inverting input terminal of the amplifier and an output terminal of the amplifier, and
the output terminal is configured to output the first voltage based on the electric charges accumulated in the capacitor.

5. The measurement circuit according to claim 3 , further comprising a transistor, wherein
the capacitor is connected to a gate of the transistor, and
the gate of the transistor is configured to generate the first voltage based on the electric charges accumulated in the capacitor.

6. The measurement circuit according to claim 1 , wherein the circuitry is further configured to:
generate a ramp wave having a third voltage that changes in a slope shape, wherein the ramp wave is generated based on the first voltage;
compare a fourth voltage with the ramp wave; and
output a comparison result as the first pulse signal based on the comparison of the fourth voltage with the ramp wave.

7. The measurement circuit according to claim 1 , wherein the circuitry is further configured to:
generate a ramp wave having a third voltage that changes in a slope shape;
compare the first voltage with the ramp wave; and
output a comparison result as the first pulse signal based on the comparison of the first voltage with the ramp wave.

8. A driving method, comprising:
controlling a first light emitting diode (LED) to start emission of first light at a start of a first light emission period, wherein the first light is emitted towards an object;
receiving the first light reflected by the object;
generating a first current based on the received first light;
executing integration of the generated first current in the first light emission period, wherein the integration of the generated first current is completed before an end of the first light emission period;
controlling the first LED to stop the emission of the first light at the end of the first light emission period;
generating a first voltage based on the integration of the generated first current;
generating a first pulse signal having a pulse width based on the generated first voltage;
controlling a second light emitting diode (LED) to start emission of second light at a start of a second light emission period, wherein
the second light is emitted towards the object, and
the second light emission period is different from the first light emission period;

receiving the second light reflected by the object;
generating a second current based on the received second light;
executing integration of the generated second current in the second light emission period, wherein the integration of the generated second current is completed before an end of the second light emission period;
controlling the second LED to stop the emission of the second light at the end of the second light emission period;
generating a second voltage based on the integration of the generated second current;
generating a second pulse signal having a pulse width based on the generated second voltage;
measuring a first number of clocks in a first pulse width period of the first pulse signal, wherein
the measurement is stopped during the first light emission period, and
the measurement of the first number of clocks is executed after the end of the first light emission period and before a start of the second light emission period;

measuring a second number of clocks in a second pulse width period of the second pulse signal, wherein
the measurement is stopped during the second light emission period, and
the measurement of the second number of clocks is executed after the end of the second light emission period; and

generating digital measurement data based on the measured first number of clocks and the second number of clocks.

9. An electronic instrument, comprising:
a first light emitting diode (LED);
a second LED;
a counter; and
circuitry configured to:
control the first LED to start emission of first light at a start of a first light emission period, wherein the first light is emitted towards an object;
receive the first light reflected by the object;
generate a first current based on the received first light;
execute integration of the generated first current in the first light emission period, wherein the integration of the generated first current is completed before an end of the first light emission period;
control the first LED to stop the emission of the first light at the end of the first light emission period;
generate a first voltage based on the integration of the generated first current;
generate a first pulse signal having a pulse width based on the gen

Assignees

• Sony Corp

Inventors

• Sako Michiya
• Kitada Masatoshi

Classifications

• A61B5/6826

  Finger · CPC title

• A61B5/1455

  using optical sensors, e.g. spectral photometrical oximeters · CPC title

• A61B2560/0209

  adapted for power saving · CPC title

• G01J1/46

  using a capacitor · CPC title

• A61B5/7225

  Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316) · CPC title