JP2001356247A - Lighting equipment - Google Patents

Abstract

(57) [Problem] To provide a lighting device using an optical fiber, which has high luminance, low loss, low cost, and small size. A light source including one or more light emitting elements.
And one or more optical fibers 4, a lens 3 for condensing light from the light source 10 and entering the optical fibers 4, and a power supply device 5 for turning on the light emitting element 2. Lighting equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device using an optical fiber.

[0002]

2. Description of the Related Art For example, in the field of manufacturing semiconductors, liquid crystals, films, etc., in order to judge the quality of products,
Inspection by image processing using a CCD camera, a computer, and the like, and inspection by the inspector's eyes are performed. In the case of performing such an inspection, it is necessary to perform high-intensity uniform illumination on the product at the time of imaging or visual observation. For example, an illumination device including an optical fiber and a light source device is preferably used. A lighting device using an optical fiber is basically configured so that light from a light source device is incident on an incident end surface at one end of the optical fiber and is emitted from an emission surface at the other end. I have. The lighting device using such an optical fiber is relatively small since the light emitting portion is formed by the emission end face of the optical fiber, and can bend the optical fiber freely, so that it is close to the object to be illuminated (the object to be illuminated). There is an advantage that the light source can be illuminated from a short distance by arranging the light source unit at a short distance, and that the light source device can be installed in a place where the operation and maintenance are easy, since the degree of freedom is high. By the way, as a light source device constituting a lighting device using such an optical fiber, for example, a halogen lamp, a high-intensity discharge lamp,
A device provided with a light emitting body such as an LED (Light Emitting Diode) is used. Among these light emitters, LEDs have a long life and generate less heat due to light emission, which is preferable in forming a light source device. However, since the amount of light per light is small, a plurality of LEDs are collected to form one light emitter. Often configured.

However, if a light emitting body is formed by arranging a large number of LEDs in order to secure a necessary light emitting amount, the light emitting area of the light emitting body becomes large, so that light emitted from the light emitting body has a relatively small diameter. There is a problem that it is difficult to make the light efficiently enter the end face of the optical fiber. Therefore,
For example, Japanese Patent Application Laid-Open No. H11-219608 discloses that, as shown in FIG. 3, light emitted from a large number of LEDs 21 arranged on a plane is condensed into a substantially frustoconical shape having a tapered peripheral surface. A configuration in which the light is condensed by the member 22 and made incident on the optical fiber 23 is described. Also, JP-A-7-2125
No. 37 discloses that a plurality of LEDs are arranged in an integrating sphere,
There is described a configuration in which light emitted from this is reflected in an integrating sphere and condensed on an incident end face of an optical fiber.

[0004]

However, in the case of using a light collecting member 22 having a substantially frusto-conical shape as shown in FIG. 3, when the number of LEDs 21 is further increased to obtain high-luminance illumination light. There was a problem that it was difficult to respond. That is, since the light emitting area increases as the number of the LEDs 21 increases, the optical fiber 2
In order to converge light on the incident end face of No. 3, the taper angle of the peripheral surface of the condensing member 22 is increased as shown in FIG. 4 to cope with an increase in the light emitting area, or as shown in FIG. It is necessary to increase the light emitting area of the LED 21 by increasing the length of the light collecting member 22 in the optical axis direction while keeping the taper angle of the surface unchanged. However, as shown in FIG. 4, when the taper angle of the peripheral surface is increased, the angle of reflection of light on the peripheral surface is increased and the light transmission efficiency is reduced.
Has a larger output NA (numerical aperture) than the incident NA of the optical fiber 23, which causes a problem that the coupling loss between the light condensing member 22 and the optical fiber 23 increases. On the other hand, when the length of the light collecting member 22 is increased as shown in FIG. 5, the distance over which the light is transmitted in the light collecting member 22 is increased, so that the transmission efficiency is reduced and the size of the light source device is increased. The problem arises. Further, the light collecting member 22
Is relatively expensive which requires high transparency and polishing, and there is also a problem that an increase in the volume of the light condensing member 22 causes an increase in cost. On the other hand, the method of condensing light by using an integrating sphere has a problem that the loss in the integrating sphere is so large that a sufficient amount of light cannot be obtained, and that the integrating sphere is expensive and large and is vulnerable to impact.

The present invention has been made in view of such circumstances, and has as its object to provide a high-luminance, low-loss, inexpensive, and compact lighting device.

[0006]

In order to solve the above-mentioned problems, a lighting device according to the present invention comprises a light source having one or more light-emitting elements, one or more optical fibers, and light from the light source. It is characterized by comprising a lens for condensing light and entering the optical fiber, and a power supply device for turning on the light emitting element. It is preferable that the light emitting element is one of a light emitting diode and a laser diode. As the light emitting diode, it is preferable to use a shell type light emitting diode in which the directional angle of emitted light is 25 degrees or less. It is preferable to use a Fresnel lens as the lens. It is preferable to use a plastic optical fiber as the optical fiber. It is preferable that the power supply device includes a constant current circuit. It is preferable that the power supply device further includes a current adjustment circuit that adjusts a current value in the constant current circuit. It is preferable that the light source includes a plurality of light emitting elements having different emission wavelengths.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram showing one embodiment of a lighting device according to the present invention. In the figure, reference numeral 2 denotes a light emitting element, 3 denotes a lens, 4 denotes an optical fiber, 5 denotes a power supply device, 10
Indicates a light source. In the present embodiment, the light source 10
Is configured by mounting a plurality of light emitting elements 2 on a substrate 1. The light emitting elements 2 are arranged adjacent to each other on the substrate 1 so as to have a substantially regular hexagonal shape as shown in FIG. As the light emitting element 2, an LED or a laser diode (Laser Diode, sometimes abbreviated as LD hereinafter) is preferably used. In the present invention, it is preferable that the light emitting element 2 has a directivity angle of 25 degrees or less, and among the LEDs, a bullet-type LED or a LED with a reflecting mirror with a directivity angle of 25 degrees or less is preferable. It is more preferable because it is very small and has a large light emission amount. LDs are also preferable because they have a small directivity angle of 25 degrees or less, are relatively small, and emit a large amount of light. Here, the directivity angle of the light emitting element refers to the maximum value of the angle between the optical axis of the light emitting element and the emitted light. If the directivity angle of the light emitting element 2 is 25 degrees or less, the light emitted from the light source 10 becomes substantially parallel light, so that the light can be efficiently collected by the lens 3 and incident on the optical fiber 4 with low loss.

The lens 3 is disposed so as to face the light emitting surface of the light source 10, that is, the light emitting element 2 mounted on the substrate 1, and collects light emitted from the light source 10. Lens 3
A light emitting element whose effective area is larger than the light emitting area of the light source 10, that is, the area where the light emitting element 2 is mounted on the substrate 1 is used. The effective area of the lens 3 is preferably equal to or slightly larger than the light emitting area of the light source. An incident end face 4a of the optical fiber 4 is disposed on the central axis of the lens 3, and the light condensed by the lens 3 is incident on the incident end face 4a. As the lens 3, any shape can be used as long as the light emitted from the light source 10 can be focused on the incident end face 4a of the optical fiber 4, and for example, a Fresnel lens or a convex lens can be used. Fresnel lenses are particularly preferred because they are thin and relatively inexpensive.

The optical fiber 4 may have any configuration as long as it has an optical transmission function.
The optical fiber cable may be a single-core wire composed of a plurality of optical fibers or an optical fiber cable formed by assembling a plurality of optical fibers. The material of the optical fiber 4 is not particularly limited, and a glass-based or plastic-based material can be used. In particular, a plastic optical fiber is preferable because it is inexpensive and has good flexibility.

A power supply device 5 is provided so as to be electrically connected to the light emitting element 2 constituting the light source 10. The power supply device 5 is provided with a circuit for turning on the light emitting element 2 by supplying a current to the light emitting element 2 at least, and is preferably provided with a constant current circuit. Light emitting element 2 by constant current circuit
When a constant current is applied to the light-emitting element to turn on the light-emitting element 2, the light-emitting element 2 is prevented from fluctuating with time and the light-emitting light quantity from the light source 10 is stabilized. In addition, it is preferable that a constant current circuit be provided in the power supply device 5 and a current adjustment circuit that adjusts a current value in the constant current circuit be provided. By providing the current adjustment circuit, it is possible to control the value of the current flowing through the light emitting element 2, thereby controlling the light emitting element 2 from a light-off state to a light-on state with the maximum light amount. When the current value to the light emitting element 2 is 0 mA, the light is turned off. The upper limit of the current flowing to the light emitting element 2 is determined by the maximum power consumption determined by the rating of the light emitting element 2. Further, by providing the current adjustment circuit, it is possible to switch between a DC current in which a current continuously flows through the light emitting element 2 and a pulse current in which a current flows intermittently through the light emitting element 2 as necessary. If a pulse current is applied to the light emitting element 2, it can be turned on only at the time of photographing, for example, in synchronization with the timing of photographing the illuminated object (imaging cycle).

In order to illuminate using the illuminating device having such a configuration, first, the light source 10 is turned on by causing the power supply device 5 to supply a current to the luminous element 2 to cause the luminous element 2 to emit light. The light emission amount of the light emitting element 2 increases and decreases according to the current value. Since the light emitted from the light source 10 enters the lens 2 and is collected toward the focal point of the lens 2, the incident end face 4 a of the optical fiber 4 should be arranged on the optical path of the light emitted from the lens 2. As a result, the collected light is incident on the optical fiber 4. Since the incident light is transmitted through the optical fiber 4 and is emitted from the emission end face 4b of the optical fiber 4, the light emitted from the optical fiber 4 is illuminated on the object to be illuminated as illumination light.

According to the illuminating device of the present embodiment, the light emitted from the large number of light emitting elements 2 mounted on the substrate 1 is condensed by using the lens 3, so that the light can be condensed in a short distance. Therefore, the loss of light is small, and the lighting device can be made compact. Since the lens 3 is relatively inexpensive, the cost can be kept low. In addition, even when the number of light emitting elements 2 increases, it is possible to easily cope with the problem by increasing the effective area of the lens 3, and the loss of light does not increase as the number of light emitting elements 2 increases. In addition, high-luminance illumination light can be efficiently obtained.

Further, since a constant current circuit is provided in the power supply device 5 and the light emitting element 2 is lit by the constant current circuit, fluctuations in the amount of light emitted from the light emitting element 2 are prevented, so that illumination light having excellent luminance stability is provided. Is obtained. In addition, by providing a current adjusting circuit in the power supply device 5 so as to adjust the value of the current flowing through the light emitting element 2, it is possible to adjust not only the blinking of the light emitting element 2 but also the light emission amount of the light emitting element 2. The brightness of light can be controlled freely. Further, it is possible to control the pulse current of a predetermined cycle from the constant current circuit to the light emitting element 2 by the current adjusting circuit. Of the illumination light can be pulse-lit in synchronization with the imaging cycle of imaging the object to be illuminated. Also,
Although the maximum power consumption of the light emitting element 2 is determined by the rating of the light emitting element 2, when the pulse forward current is passed, for example, it is larger than that when the DC forward current is continuously passed because the power is not consumed when the light is turned off. It is possible to pass a forward current. Therefore, brighter illumination light can be obtained by pulsing the light emitting element 2 using the current adjustment circuit.

Further, as another embodiment of the present invention, it is preferable that the light source 10 be constituted by using a plurality of types of light emitting elements 2 having different emission wavelengths. In this case, it is preferable that a constant current circuit and a current adjusting circuit are provided for each light emitting element of each wavelength or for each light emitting element, so that the amount of emitted light of each wavelength can be controlled. With such a configuration, the color of the illumination light emitted from the optical fiber 4 can be arbitrarily changed.

In the above embodiment, the plurality of light emitting elements 2
Although the surface (mounting surface) on which is mounted is a flat surface, the shape of the mounting surface is arbitrary, and the shape of the substrate 1 can be changed as appropriate. The arrangement and number of the light emitting elements 2 on the substrate 1 can be changed as appropriate. The mounting form of the light emitting element 1 is preferably changed according to the shape of the lens 3.
And a plurality of light emitting elements 2 are preferably arranged in a dense manner so that there is as little space as possible, in order to efficiently obtain bright illumination light while reducing the size of the light source.

[0016]

Embodiments of the present invention will be described below. (Example 1) The lighting device shown in FIG. 1 was configured using a shell-type LED (directivity angle = 25 degrees or less) having a diameter of 3 mm to 5 mm as the light emitting element 2. That is, as shown in FIG. 2, a plurality of LEDs having the same emission wavelength are mounted side by side on a circular substrate 1 having a radius of 30 mm without any gap, and a light source 10 is mounted.
Was configured. Also, radius 30mm, focal length 20mm ~
A 40 mm Fresnel lens 3 was arranged opposite to the LED so as to be coaxial with the substrate 1. Near the focal position on the central axis of the Fresnel lens 3, the incident end face 4a of the optical fiber 4
Are arranged such that the central axis of the Fresnel lens 3 and the incident end face 4a are perpendicular to each other. When a DC forward current is applied to the LED by the constant current circuit of the power supply device 5 and the current value per LED is adjusted from 0 mA to 100 mA by the current adjustment circuit to adjust the light emission amount of the LED, the emission end of the optical fiber 4 4b emitted illumination light of a single wavelength, and the brightness of the illumination light changed according to the current value. Current value is 0 mA
At the time, the light was turned off.

(Embodiment 2) In the first embodiment, a plurality of LEDs having different emission wavelengths, that is, a plurality of LEDs emitting red light, LEDs emitting green light, and LEDs emitting blue light are used as the plurality of LEDs. The lighting device was constructed in the same manner except that a constant current circuit and a current value adjusting circuit were provided. The arrangement of the LEDs on the substrate 1 is regularly arranged so that LEDs of the same emission color are not adjacent to each other, for example, a mosaic arrangement pattern referred to as a color filter or the like. A DC forward current is supplied to the LED by each constant current circuit, and LE is controlled by each current adjustment circuit.
When the light emission amount of each color LED was adjusted by adjusting the current value per D from 0 mA to 100 mA, the emission end of the optical fiber 4 was adjusted according to the ratio of the magnitude of the current value in each color LED. The color of the illumination light emitted from 4b has changed.

(Example 3) A lighting device was constructed in the same manner as in Example 1 except that an LD was used as the light emitting element 2. When a DC forward current is supplied to the LD by the constant current circuit of the power supply device 5 and the current value per LD is adjusted from 0 mA to 100 mA by the current adjustment circuit to adjust the light emission amount of the LD, the emission end of the optical fiber 4 is obtained. 4b emitted single-wavelength illumination light, and the brightness of the illumination light changed in proportion to the current value. When the current value was 0 mA, the light was turned off.

[0019]

According to the present invention, a light source including one or more light emitting elements, one or more optical fibers, a lens for condensing light from the light source and making the light incident on the optical fibers,
By providing a power supply device for lighting the light-emitting element to constitute a lighting device, a high-luminance, low-loss, inexpensive, and compact lighting device can be realized. Further, the lighting device of the present invention,
Since the emission part of the illumination light is composed of the end face of the optical fiber, it is relatively small, and the optical fiber can be bent freely, so that the emission part can be arranged near the illuminated object to perform illumination from a short distance. Also, there is an advantage that the light source can be installed in a place where the degree of freedom of the light source is high and the operation and maintenance are easy.

The light emitting element in the present invention is preferably a light emitting diode or a laser diode. In particular, when the directional angle of the light emitting element is 25 degrees or less, the light emitted from the light source becomes substantially parallel light, so that the light is efficiently collected by the lens. It is preferable because light can be incident on the optical fiber with low loss. As a lens, a Fresnel lens is particularly preferable because it is relatively small and inexpensive. As the optical fiber, a plastic optical fiber is particularly preferable because it is inexpensive and has good flexibility.

Further, by providing a constant current circuit in the power supply device and supplying a constant current to the light emitting element and lighting the light emitting element, fluctuation of the light emission amount of the light emitting element is prevented, and the luminance of the illumination light is stabilized. Further, by providing a current adjusting circuit in the power supply device, it is possible to control the value of the current flowing through the light emitting element, thereby adjusting the amount of light emitted from the light emitting element and controlling the luminance of the illumination light. . In addition, pulsed lighting can be performed by supplying a pulse current to the light emitting element. When a single-wavelength light-emitting element is used, monochromatic illumination light with a narrow half-value width can be obtained, and when a plurality of light-emitting elements with different emission wavelengths are used, illumination light of any color can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a lighting device of the present invention.

FIG. 2 is a plan view showing an arrangement of light emitting elements in the lighting device of FIG.

FIG. 3 is a schematic configuration diagram illustrating an example of a conventional lighting device.

FIG. 4 is a schematic configuration diagram showing an example of a conventional lighting device.

FIG. 5 is a schematic configuration diagram illustrating an example of a conventional lighting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Light emitting element, 3 ... Lens, 4 ... Optical fiber, 5 ... Power supply device, 10 ... Light source.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // F21Y 101: 02 F21S 1/02 G F term (reference) 2H037 BA03 CA12 5F041 AA04 AA47 BB32 DA82 DB01 DC83 DC84 EE01 EE04 EE11 FF11

Claims (8)

[Claims] A light source having at least one light emitting element;
A lighting device comprising: at least one optical fiber; a lens for condensing light from the light source to be incident on the optical fiber; and a power supply device for turning on the light emitting element. 2. The lighting device according to claim 1, wherein the light emitting element is one of a light emitting diode and a laser diode. 3. The lighting device according to claim 2, wherein a shell-type light emitting diode having a directivity angle of emitted light of 25 degrees or less is used as said light emitting diode. 4. The lighting device according to claim 1, wherein a Fresnel lens is used as the lens. 5. The lighting device according to claim 1, wherein a plastic optical fiber is used as the optical fiber. 6. The lighting device according to claim 1, wherein the power supply device includes a constant current circuit. 7. The lighting device according to claim 6, wherein the power supply device further includes a current adjusting circuit for adjusting a current value in the constant current circuit. 8. The lighting device according to claim 1, wherein the light source includes a plurality of light emitting elements having different emission wavelengths.