JP2014082383A - Light-emitting unit, light-emission control unit, and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the amount of luminescence at high speed.SOLUTION: A light-emitting unit 11 has a light-emitting element 17 and a resistor 18. The light-emitting element 17 is such that its amount of luminescence and calorific power change. The resistor 18 is disposed in close vicinity to the light-emitting element 17. The resistor 18 generates heat with such calorific power that total calorific power, with the calorific power of the light-emitting element added, is substantially constant with respect to a change in the amount of luminescence of the light-emitting element.

Description

  The present invention relates to a light emitting unit capable of emitting light with a stable light emission amount, a light emission control unit, and a light emitting device.

  For inspection of optical equipment, light emitting devices that illuminate the optical equipment with various brightnesses are used. Conventionally, a discharge tube such as a xenon lamp or a halogen lamp has been used as a light source of a light emitting device. In recent years, light emitting elements such as LEDs have been used as light sources of light emitting devices.

  In a light-emitting element such as an LED, the amount of light emission varies not only with the energized current but also with temperature. Therefore, while the light emitting device is required to emit light with a desired light emission amount, it is difficult for the light emitting element to emit light with a stable light emission amount.

  Therefore, in a configuration in which the current flowing to the light emitting element is determined according to the inflow current to the light receiving element that detects the light emission amount of the light emitting element, the temperature change is controlled by controlling the inflow current to the light receiving element to be always constant. It has also been proposed to stabilize the amount of emitted light (see Patent Document 1).

Japanese Patent Laid-Open No. 11-63979

  In the light emitting device used for the above-described inspection, it is required to switch the light emission amount at high speed in order to increase the inspection speed. When the current supplied to the light-emitting element is adjusted, the temperature of the light-emitting element itself varies due to the change in the current. Therefore, the light emission amount varies until the temperature is stabilized. For this reason, even if it is controlled to emit light with a desired light emission amount, the light emission amount may become unstable depending on the response time of the control. Therefore, it has been difficult to switch and stabilize the light emission amount at high speed.

  Accordingly, an object of the present invention made in view of such circumstances is to provide a light-emitting unit, a light-emission control unit, and a light-emitting device capable of stabilizing the light emission amount at high speed.

In order to solve the above-mentioned problems, the light emitting unit according to the first aspect is
A light emitting element in which the light emission amount and the heat generation amount are changed;
And a resistor that is disposed in the vicinity of the light emitting element and generates heat with a calorific value such that a total amount of the calorific value of the light emitting element is substantially constant with respect to a change in the amount of light emitted from the light emitting element. Is.

The light emitting unit according to the second aspect is
It is preferable that the heat generation amount with respect to the flowing current is substantially the same between the light emitting element and the resistor.

The light emitting unit according to the third aspect is
The light emitting element is preferably an LED chip.

The light emitting unit according to the fourth aspect is
The resistor is incorporated in the same chip as the LED chip.

The light emission control unit according to the fifth aspect is
A light emitting element in which the light emission amount and the heat generation amount are changed, and a heat generation amount that is disposed in the vicinity of the light emitting element, and the sum of the heat generation amount of the light emitting element is substantially constant with respect to the change in the light emission amount of the light emitting element. A heat generating resistor, and a heat generation amount with respect to a flowing current is substantially the same between the light emitting element and the resistor, and the light emitting element and the resistor are subjected to a change in the light emitting amount of the light emitting element of the light emitting unit. The resistor is provided with a current control unit for energizing the current so that the sum of the flowing currents is substantially constant.

The light emission control unit according to the sixth aspect is
The light emission amount of the light emitting element is changed by adjusting a current to be supplied to the light emitting element by PWM control, and the current control unit supplies a current having a waveform obtained by inverting the waveform of the PWM control to the resistor. Is preferred.

The light emitting device according to the seventh aspect is
A light emitting element in which the light emission amount and the heat generation amount are changed, and a heat generation amount that is disposed in the vicinity of the light emitting element, and the sum of the heat generation amount of the light emitting element is substantially constant with respect to the change in the light emission amount of the light emitting element. A light emitting unit comprising a resistor that generates heat;
A photometric sensor for detecting the light emission amount of the light emitting element;
A current to be supplied to the light emitting element is adjusted based on a light emission amount detected by the photometric sensor, and a current to be supplied to the resistor is adjusted so that a total heat generation amount of the light emitting element and the resistor is substantially constant. And a control unit for adjustment.

  According to the light emitting unit, the light emission control unit, and the light emitting device according to the present invention configured as described above, the light emission amount can be stabilized at high speed.

It is a functional block diagram which shows schematic structure of the light-emitting device which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a light emitting unit, a light emission control unit, and a light emitting device according to an embodiment of the present invention will be described. FIG. 1 is a functional block diagram illustrating a schematic configuration of a light emitting device according to an embodiment.

  As shown in FIG. 1, the light emitting device 10 includes a light emitting unit 11, a photometric sensor 12, an amplifier circuit 13, a control unit 14, a PWM signal generation circuit 15, and a light emission control unit 16.

  The light emitting unit 11 includes a light emitting element 17 and a resistor 18. The light emitting element 17 is, for example, an LED chip, and the amount of emitted light and the amount of generated heat change according to the current that is energized. The resistor 18 has a resistance that is substantially equal to that of the light emitting element 17 in terms of heat generation characteristics with respect to a current to be applied. Accordingly, when the same current is applied, the light emitting element 17 and the resistor 18 have substantially the same temperature. The light emitting element 17 and the resistor 18 are incorporated in the same chip.

  The photometric sensor 12 detects the amount of illumination light emitted from the light emitting element 17, for example, the luminance, and outputs a signal corresponding to the amount of emitted light.

  The amplification circuit 13 amplifies the signal output from the photometric sensor 12 to a signal level that can be read by the control unit 14. The amplification circuit 13 can adjust the amplification factor in order to ensure the detection resolution from low luminance to high luminance.

  The control unit 14 recognizes the light emission amount detected by the photometric sensor 12 based on the signal adjusted by the amplifier circuit 13. The control unit 14 includes, for example, a differential circuit and an integration circuit, or an A / D conversion circuit, an MPU, and a D / A conversion circuit, and performs feedback control so that the light emission amount of the light emitting element 17 matches the set value. The control unit 14 outputs the duty ratio as a signal in order to adjust the light emission amount of the light emitting element 17 by PWM control.

  The PWM signal generation circuit 15 includes a triangular wave generation circuit and a comparator, for example, and outputs a PWM signal corresponding to the duty ratio output from the control unit 14.

  The light emission control unit 16 includes a first current control unit 19 and a second current control unit 20. The first current control unit 19 is a transistor, for example, and switches ON / OFF of a current to be supplied to the light emitting element 17 in accordance with a PWM signal output from the PWM signal generation circuit 15. The second current control unit 20 is, for example, an inverting amplifier circuit, and switches ON / OFF of a current supplied to the resistor 18 according to a waveform obtained by inverting the output signal from the PWM signal generation circuit 15.

  According to the light emitting unit of the present embodiment configured as described above, the resistor 18 disposed close to the light emitting element 17 generates heat, and the light emitting element 17 and the resistor 18 generate heat even when the light emission amount is changed. It is possible to keep the total amount constant. Therefore, even when the duty ratio of the current to be supplied to the light emitting element 17 is changed, the heat generation amount of the entire light emitting unit 11 is constant and the temperature of the light emitting element 17 is substantially constant, so that the light emission amount is stabilized at high speed. It is possible to make it.

  Further, according to the light emitting unit of the present embodiment, the heat generation characteristics with respect to the current of the light emitting element 17 and the resistor 18 are substantially the same. Therefore, it is possible to easily keep the heat generation amount of the entire light emitting unit 11 constant by keeping the total amount of current to be supplied to the light emitting element 17 and the resistor 18 constant.

  Further, according to the light emitting unit of the present embodiment, since the light emitting element 17 and the resistor 18 are incorporated in the same chip, for example, the temperature of the entire light emitting surface can be made constant when the multichip light emitting unit 11 is formed. It is. For example, when a multi-chip LED is cooled by providing a temperature adjustment mechanism, a temperature gradient may occur along the light emitting surface. On the other hand, in this embodiment, since the temperature of each light emitting unit 11 is kept constant, a temperature gradient does not occur and the entire temperature can be made constant.

  Further, according to the light emission control unit of the present embodiment, it is possible to supply the resistor 18 with a current adjusted with a signal having a waveform obtained by inverting a PWM signal for adjusting a current supplied to the light emitting element 17. Therefore, according to the light emission control unit 16, it is possible to keep the total current flowing through the light emitting element 17 and the resistor 18 substantially constant before and after the change in the light emission amount of the light emitting element 17. As described above, since the heat generation characteristics of the light emitting element 17 and the resistor 18 with respect to the current are substantially the same, the temperature in the light emitting unit 11 can be stabilized by the control of the light emission control unit 16.

  Although the present invention has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various changes and modifications based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Light-emitting device 11 Light-emitting unit 12 Photometric sensor 13 Amplifier circuit 14 Control part 15 PWM signal generation circuit 16 Light-emission control unit 17 Light-emitting element 18 Resistor 19 1st electric current control part 20 2nd electric current control part

Claims (7)

A light emitting element in which the light emission amount and the heat generation amount are changed;
And a resistor that is disposed in the vicinity of the light emitting element and generates heat with a calorific value such that a total amount of the calorific value of the light emitting element is substantially constant with respect to a change in the amount of light emitted from the light emitting element. Light emitting unit.   The light-emitting unit according to claim 1, wherein a heat generation amount with respect to a flowing current is substantially the same between the light-emitting element and the resistor.   3. The light emitting unit according to claim 1, wherein the light emitting element is an LED chip.   4. The light emitting unit according to claim 3, wherein the resistor is incorporated in the same chip as the LED chip.   3. A current for passing a current through the resistor so that a total of currents flowing through the light emitting element and the resistor is substantially constant before and after a change in light emission amount of the light emitting element of the light emitting unit according to claim 2. A light emission control unit comprising a control unit.   6. The light emission control unit according to claim 5, wherein the light emission amount of the light emitting element is changed by adjusting a current supplied to the light emitting element by PWM control, and the current control unit inverts the waveform of the PWM control. A light emission control unit, wherein a current having a waveform is applied to the resistor. The light emitting unit according to claim 1;
A photometric sensor for detecting the light emission amount of the light emitting element;
A current to be supplied to the light emitting element is adjusted based on a light emission amount detected by the photometric sensor, and a current to be supplied to the resistor is adjusted so that a total heat generation amount of the light emitting element and the resistor is substantially constant. A light emitting device comprising: a control unit that adjusts.

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