Optical sensor

Abstract

To provide an optical sensor ensuring durability.SOLUTION: An optical sensor includes: a light projection section for generating light projection beams by a light source element; a light reception section for outputting a detection signal by receiving reflection beams; and a control section for controlling the light projection section and the light reception section. The control section is configured to execute monitoring of a heat propagation temperature Tt propagated to the periphery of the light source element in the light projection section, and controlling of light emission output Pl in the light source element so as to absorb an efficiency change amount of light emission efficiency that decreases according to an increase in the heat propagation temperature Tt in the light source element and a temperature change amount of a junction temperature Tj in the light source element so as to be correlated with the heat propagation change amount of the heat propagation temperature Tt.SELECTED DRAWING: Figure 9

Claims

1. An optical sensor (10) that emits a light beam (Bp) and receives a reflected beam (Br) reflected from the light beam, A light-emitting unit (21) that generates the light-emitting beam using a light source element (24), A light receiving unit (41) that receives the reflected beam and outputs a detection signal, The system includes a control unit (51) that controls the light-emitting unit and the light-receiving unit, The control unit, The light-emitting unit monitors the heat transfer temperature (Tt) transferred to the surrounding light source element, An optical sensor configured to perform the following actions: control the light emission output (Pl) of the light source element to absorb the amount of temperature change that rises from the upper limit of the allowable temperature range of the junction temperature (Tj) in the light source element, which is correlated with the amount of efficiency change of the light emission efficiency that decreases in accordance with the rise in the heat transfer temperature of the light source element and the amount of heat transfer change of the heat transfer temperature.

2. The control unit, The optical sensor according to claim 1, wherein the light emission output is controlled by adjusting the voltage (Vl) applied to the light source element so as to absorb the amount of temperature change.

3. The control unit, The optical sensor according to claim 1, wherein the heat transfer temperature is set to a reference heat transfer range (τt) corresponding to the allowable temperature range that is permissible for the junction temperature, and the light emission output is controlled to absorb the amount of temperature change when the heat transfer temperature rises outside the reference heat transfer range.

4. The control unit, The allowable output range for the aforementioned light emission output is defined as the allowable output range (ρl). The optical sensor according to claim 3, wherein when the heat transfer temperature rises outside the reference heat transfer range, the light emission output is controlled within the allowable output range to absorb the amount of temperature change.

5. The control unit, The optical sensor according to claim 4, wherein the light emission output is controlled within the allowable output range by maintaining the applied voltage (Vl) to the light source element when the heat transfer temperature is within the reference heat transfer range.

6. The control unit, The optical sensor according to claim 5, wherein the light emission output is maintained at the maximum output (Plu) of the allowable output range when the heat transfer temperature within the reference heat transfer range is in a low-temperature range (τtl) that is lower than the high-temperature range (τth) that maintains the applied voltage (Vl) to the light source element.

7. The light-emitting unit is The light source unit (22) is provided with a plurality of light source elements that generate the light beam, The control unit, The heat transfer temperature from each of the light source elements to a common surrounding location is monitored. The optical sensor according to any one of claims 1 to 6, wherein the light emission output for each light source element is individually controlled so as to absorb the amount of temperature change for each light source element.

8. The light-emitting unit is A power supply circuit (2) that supplies the power supply voltage (Vs), It includes an adjustment circuit (4) that adjusts the voltage (Vl) applied to the light source element from the power supply voltage, The control unit, The optical sensor according to any one of claims 2, 5, or 6, which controls the power supply circuit to absorb fluctuations in the power supply voltage corresponding to the rise and fall of the heat transfer temperature.

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