JP2001043728A - Light emitting diode lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting diode lighting system which does not have fluctuating light quantity due to temperature. SOLUTION: A plurality of LEDs arrayed by a prescribed pattern on a substrate are fitted into a heat radiating plate 32, on which LED insertion holes of the same pattern are punched. The LEDs emit light by current pulses supplied from an LED drive part 53. On the heat radiating plate, thermocouples 51 for detecting a temperature of the heat radiating plate and thermo modules 52 for absorbing heat on the heat radiating plate are arranged. A temperature control part 54 determines current for driving the thermo modules 52 for controlling the temperature of the heat radiating plate detected by the thermocouples 51 at a set temperature. Therefore, rise in temperature is suppressed, even if the system is used over a long time, and fluctuation of light quantity is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode illuminating device, and more particularly to a light emitting diode illuminating device capable of obtaining a predetermined amount of light regardless of temperature.

[0002]

2. Description of the Related Art In order to inspect whether a mold or a component such as a relay is finished in a shape and a dimension as designed,
It is known to use images taken by a television camera or the like. In order to obtain an image with a television camera or the like, it is necessary to appropriately illuminate the object to be photographed. Conventionally, illumination using a halogen lamp or a fluorescent lamp as a light source has been used.

However, a halogen lamp or a fluorescent lamp has a short life and requires frequent replacement, and it is difficult to obtain a predetermined directivity characteristic. That is, when measuring the dimensions of a predetermined portion by performing image processing, a light source such that a shadow is not included in an image photographed by a television camera so that an image is not clear due to a shadow and the measurement of the dimension by the image is not inaccurate. It is necessary to adjust the installation. However, when using a halogen lamp or fluorescent lamp,
Since there is only one light source, the irradiation direction of the light source had to be adjusted by trial and error.

[0004] In order to solve this problem, there has been proposed a light emitting diode lighting device in which a plurality of light emitting diodes (LEDs) are embedded in a substrate. FIG. 1 is a top view (a), an AA cross-sectional view (b), and a partially enlarged view (c) of an example of a conventional light emitting diode lighting device. That is, it has a configuration in which a plurality of LEDs 11 are arranged concentrically inside the concave mirror 10. An imaging hole 12 is formed at the center of the concave mirror 10.

[0005] Such a light-emitting diode illuminating device can select the wavelength (color) of the illuminating light, has a short response time, and has a desired directional characteristic because each LED can be regarded as a point light source. It has advantages such as easy realization.

[0006]

SUMMARY OF THE INVENTION However, LEDs
Has the characteristic that the luminous intensity decreases as its temperature rises. Therefore, the conventional light emitting diode lighting device has a problem that the luminous intensity gradually decreases as time elapses after lighting. FIG. 2 is a graph of a surface luminous intensity fluctuation characteristic of a conventional light emitting diode lighting device, wherein (a) shows time-luminance characteristics and (b) shows time-temperature characteristics. The mark "◆" is LE
D indicates the case where the lighting duty ratio of D is set to the maximum, and Δ indicates the case where the lighting duty ratio of the LED is set to about 50%.

As can be understood from this graph, the LED
When the lighting duty ratio is set to the maximum, the temperature of the conventional light emitting diode illuminating device rises by about 60 degrees and the light quantity decreases to about 2/3 in about 10 minutes. Then, when the light amount decreases, an error may occur when measuring the dimensions of the imaging target based on the image. Further, when the ambient temperature changes, the luminous intensity also fluctuates due to the change in the ambient temperature, which causes an error.

The present invention has been made in view of the above problems, and has as its object to provide a light-emitting diode illuminating device whose light quantity does not vary with temperature.

[0009]

A light emitting diode illuminating device according to the present invention is fitted with a plurality of light emitting diodes by a plurality of light emitting diodes and an insertion hole formed in accordance with an arrangement pattern of the plurality of light emitting diodes. The heat radiating plate includes a heat radiating plate and heat removing means for removing heat from the heat radiating plate. In the present invention, the heat generated by the light emitting diode is transmitted to the heat sink fitted to the light emitting diode, and is further removed by the heat removing means installed on the heat sink, so that the temperature of the light emitting diode rises. Is prevented.

[0010]

FIG. 3 is a block diagram of a first embodiment of a light emitting module used in a light emitting diode lighting device according to the present invention, in which LEDs 31 are arranged on a substrate 30 at a predetermined pitch. Is done. A heat radiating plate 32 having an LED insertion hole formed in a pattern corresponding to the arrangement pattern of the LEDs 31 is fitted and installed in the LED 31. As the heat radiating plate 32, for example, a high thermal conductivity material such as aluminum or copper is used. .

On the heat radiating plate 32, there are further provided a temperature detecting element 33 for detecting the temperature of the heat radiating plate 32 and a heat removing means 34 for removing the heat of the heat radiating plate 32. Here, as the temperature detecting element 33, a thermocouple or a thermistor can be used. In addition, the following four can be applied as the heat removing means 34.

1. Heat radiation fins 2. Heat radiation fins + cooling fan Water cooling tube 4. FIG. 4 is a comparison table of four heat removal means.
Although the radiation fin, the radiation fin + cooling fan, and the water cooling tube are all practical, they have practical disadvantages such as an increase in size or weight.

On the other hand, when a thermo module is used, the evaluation of other items is "good" and is most practical, though it is somewhat expensive. FIG. 5 is a configuration diagram of a first embodiment of a light emitting module using a thermo module as the cooling means 34. A 4 × 9 on a rectangular substrate is shown.
The case where the LED 31 of FIG. A heat sink 32 of the same size is provided on the substrate.

Four thermocouples 51 are provided along the horizontal center line of the heat radiating plate 32, and a 2 × 8 thermo module 52 is provided between an LED array having four LEDs 31 as one set. Note that the 36 LEDs 31 are LED driving units 53
The LED driving unit 53 includes a light intensity setting unit 531 and a driving current control unit 532.

That is, the luminous intensity setting unit 531 sets a duty ratio corresponding to the required luminous intensity, and the driving current control unit 532 outputs an LED driving pulse having the set duty ratio. In addition, 16 thermo modules 5
2 is controlled by the temperature control unit 54, and the temperature control unit 54 includes a temperature detection unit 541, a temperature setting unit 542, and a comparison unit 5.
43 and a thermo module control unit 544.

That is, the output of the thermocouple 51 is supplied to the temperature detector 54.
At 1, the voltage is converted to a voltage proportional to the temperature of the heat sink 32. Then, the voltage corresponding to the set temperature set by the temperature setting unit 542 and the voltage proportional to the temperature of the heat sink 32 are compared with the comparison unit 54.
3 and the thermo module control section 544 outputs a drive current for the thermo module 52 based on the voltage corresponding to the temperature deviation which is the output of the comparison section 543.

In the present embodiment, four thermocouples 51 are arranged, but the temperature detector 541 outputs a voltage proportional to the average temperature of the four locations. The same current is supplied from the thermo module control unit 544 to all 16 thermo modules 52 in order to maintain the average temperature at the set temperature. However, since the temperature of the heat radiating plate 32 is different between the peripheral portion and the central portion of the light emitting module, it is inevitable that the light amount decreases at the central portion when the temperature is controlled based on the average temperature.

FIG. 6 is a configuration diagram of a light emitting module according to a second embodiment. The light emitting module is divided into five sections. Then, the temperature control unit 54I
The temperature is controlled by ~ 54V. In addition, each temperature control unit 5
4I to 54V have the same configuration as the temperature control unit 54 shown in FIG.

Although the lighting apparatus using the thermo module as the heat removing means has been described above, it is also possible to use a finned radiating plate, a finned radiating plate + fan, and a water cooling pipe as described above. It is. Although the temperature cannot be actively controlled with only the finned heat sink, the temperature is controlled by controlling the fan rotation speed when using a fan and by controlling the amount of cooling water when using a water cooling pipe. It is possible to

[0020]

According to the light emitting diode lighting apparatus of the present invention, the heat generated by the light emitting diode is removed by the heat removing means via the heat radiating plate. A rise in temperature is suppressed, and a change in light amount can be suppressed.

Further, since the heat sink is fitted with the light emitting diode, the posture of the light emitting diode can be maintained stably.

[Brief description of the drawings]

FIG. 1 is a top view of a conventional light-emitting diode lighting device,
It is A sectional drawing and a partial enlarged view.

FIG. 2 is a graph of a surface light amount variation characteristic of a conventional light emitting diode lighting device.

FIG. 3 is a configuration diagram of a light emitting module according to the present invention.

FIG. 4 is a comparison table of heat removal means.

FIG. 5 is a configuration diagram of the first embodiment.

FIG. 6 is a configuration diagram of a second embodiment.

[Description of Signs] 30 ... Substrate 31 ... LED 32 ... Heat sink 33 ... Temperature detecting element 34 ... Heat removing means 51 ... Thermocouple 52 ... Thermo module 53 ... LED drive unit 54 ... Temperature control unit

Claims (7)

[Claims] A plurality of light emitting diodes; a heat sink fitted to the plurality of light emitting diodes by an insertion hole formed in accordance with an arrangement pattern of the plurality of light emitting diodes; And a heating means. 2. The light emitting diode lighting device according to claim 1, wherein said heat removing means is a fin connected to said heat sink. 3. The light-emitting diode illuminating device according to claim 1, wherein said heat removing means is a fan that cools said radiator plate by air. 4. The light-emitting diode illuminating device according to claim 1, wherein said heat removing means is a cooling pipe for cooling said heat sink with water. 5. A heat detecting means, wherein the heat removing means detects a temperature of the heat radiating plate, a thermo module for absorbing heat of the heat radiating plate by a Peltier effect, and the heat radiating plate detected by the temperature detecting means. The light emitting diode lighting device according to claim 1, further comprising: a temperature control unit configured to control a current supplied to the thermo module so that the temperature of the thermo module becomes a predetermined set temperature. 6. A temperature detecting means for detecting, for each section of the radiator plate divided into a plurality of sections, a representative temperature of one section of the radiator plate divided into a plurality of sections. A thermo module that absorbs heat of one section of the radiator plate divided into a plurality of sections by a Peltier effect; and that the temperature of the radiator plate detected by the temperature detecting unit becomes a predetermined set temperature. The light emitting diode lighting device according to claim 1, further comprising a temperature control means for controlling a current supplied to the thermo module. 7. The light-emitting diode illuminating device according to claim 1, further comprising a light-emitting diode driving unit that supplies a current pulse having a duty ratio according to the amount of light emitted to the plurality of light-emitting diodes. .