JP2003035883A - Optical output device, pointer and image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical output device with which a luminous flux of which the divergent angle is sufficiently small is projected by using a light emitting diode. SOLUTION: A composite lens 25 of which the central part 27 is a concave lens and the peripheral part 26 is a convex lens is arranged as a second lens group 22 in front of a light emitting diode unit 10 provided with a convex lens 16 which serves as a first lens group 21 at the end of the unit. An A-mode luminous flux directly outputted from the light emitting diode 12 of the light emitting diode unit becomes a parallel luminous flux by means of the first lens group 21 and the peripheral part 26 of the second lens group, and a B-mode luminous flux which is outputted from the light emitting diode 12 and reflected on a rear cone-shaped reflection surface 14 also becomes a parallel luminous flux by means of the first lens group 21 and the central part 27 of the second lens group. Thus, a luminous flux 55 having a small divergent angle, which is composed of the A-mode and B-mode luminous fluxes, is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light output device such as a light source device using a point light source such as a light emitting diode.

[0002]

2. Description of the Related Art A semiconductor laser is widely used as a light source of a pointer that can point a point on an image displayed on a screen or the like by using an emitted light beam such as red light. However, since laser light has high coherence and becomes high-power light, it is pointed out that there is a danger when the eye is directly irradiated, and a safer light source is required.

[0003]

The light emitted from the light emitting diode has a low coherence and does not become a high output light, so that the danger to the eye is low. However,
Compared with a semiconductor laser, the amount of emitted light is small and the divergence angle of light is large. Therefore, although it is safer than a semiconductor laser, it is not considered to be effective as a light source such as a pointer light source that requires a luminescence amount. In recent years, the amount of emitted light has been increasing with the development of light emitting diodes, but no technique has been developed for effectively reducing the divergence angle of light.

Therefore, an object of the present invention is to provide a light output device using a point light source that emits light with a large divergence angle, such as a light emitting diode, which can project a light beam with a sufficiently small divergence angle. And It is an object of the present invention to provide a light output device based on a light emitting diode, which can be sufficiently used as a light source for a pointer instead of a semiconductor laser.

Therefore, when the inventors of the present application examined the luminous flux emitted from the light emitting diode unit 10 called a lamp type as shown in FIG. 1, the light emitting diode emits light in the following radiation mode. It was found that the emitted light flux can be expressed. The light emitting diode unit 10 shown in FIG. 1 includes a light emitting diode 12 arranged substantially in the center, a reflector 13 having a cone-shaped reflecting surface 14 arranged on the rear surface (back surface) of the light emitting diode 12, and a light emitting diode. 12 has an electrode 11 for supplying electric power, and these are integrated by being molded or covered with a transparent resin 17. The resin on the front surface of the light emitting diode 12 is molded so as to be convex at the tip (front), and this portion functions as the tip convex lens 16. Therefore, the light flux emitted from the light emitting diode 12 is emitted forward along the optical axis 19 connecting the center 14 a of the reflecting surface 14 and the light emitting diode 12, and is supplied to the tip convex lens 16 after being condensed to some extent. .

This lamp type light emitting diode (chip)
Reference numeral 12 is a minute light source having a size of about 0.1 to 0.3 mm and outputs light having a large divergence angle. Therefore, 2 mm
In the optical system of the reflecting mirror of about 5 mm and the tip lens of about 5 mm, it becomes a divergent light source, that is, a point light source, and the light flux emitted from the chip 12 can be roughly classified into the following four modes. (A) A radiation mode (A mode) relating to a light beam that is emitted from the front surface of the chip 12 and does not hit the conical reflecting surface 14 but is directly refracted by the front convex lens 16 and projected forward. (B) A radiation mode (B mode) relating to a light beam that is emitted from the periphery of the chip 12 and is reflected by the conical reflecting surface 14 and then refracted by the tip convex lens 16 and projected forward. (C) A radiation mode (C mode) relating to light that is totally reflected by the side surface of the resin portion 17 of the light emitting diode light source 10 and then refracted by the tip convex lens 16 and emitted to the outside. (D) Radiation mode (D mode) relating to diffused light emitted from the side surface of the resin portion of the light emitting diode light source 10 to the outside.

Of the above radiation modes, the C-mode light and the D-mode light are too diffuse to be used in a pointer or an image projection device.
On the other hand, since the A-mode and B-mode light beams are emitted forward along the optical axis 19, they may be condensed and can be used. First, as shown in FIG. 2, by arranging the convex lens 34 in front of the light emitting diode unit 10, the divergence angle of the A mode light beam can be further reduced. However, when the convex lens is arranged, the B-mode light beam diverges and cannot be used.

On the other hand, the B-mode light beam can be made to have a small divergence angle by disposing a concave lens in front of the light emitting diode unit 10 as shown in FIG. However, the A-mode light flux diverges and cannot be used. Therefore, if only the A-mode or B-mode light beam can be output as a light beam with a small beam diameter while suppressing the divergence angle,
In order to obtain an emission amount that opposes the semiconductor laser, both A-mode and B-mode light fluxes are required. As a result, as shown in FIG. 1, the light emitting diode unit is provided with a lens (tip convex lens) 16 having a power that slightly suppresses the divergence of the A mode and does not significantly promote the divergence of the B mode. Is the limit when using as a light source.

[0009]

In view of the above, in the present invention, the second mode for converting the B-mode and A-mode light fluxes into parallel light fluxes in the vicinity of where the B-mode light flux, that is, the reflected light flux is condensed. By arranging the lens groups, it is possible to emit parallel light fluxes including light fluxes of A mode and B mode. That is, in the light output device of the present invention having a point light source and a reflector forming a cone-shaped reflecting surface on the rear surface of the point light source, a point is provided along the optical axis connecting the center of the reflecting surface and the point light source. In addition to the first lens group having a positive refractive power, which is arranged in front of the light source, the reflected light beam emitted from the reflecting surface and transmitted through the first lens group is condensed in the vicinity of the optical axis in the vicinity of the optical axis. A second lens group having negative or zero refractive power in the vicinity and positive refractive power in the periphery is arranged.

As described above, since the A-mode light flux and the B-mode light flux have different properties, it is impossible to convert them into a parallel light flux with one lens. Even if two types of lenses are arranged, they act on both the A-mode and B-mode light fluxes, so the situation cannot be improved. On the other hand, in the present invention, since the second lens group is arranged at the position where the B-mode light beam is condensed near the optical axis, the B-mode light beam has a refractive power near the optical axis. Can be made to act as a concave lens, and the light flux of A mode can be made to act as a convex lens by making the peripheral refracting power positive.
That is, by converging the B-mode light flux near the optical axis by the first lens group, the A-mode light flux and the B-mode light flux are substantially spatially separated at that position. Then, by disposing at that position a second lens group having a negative or zero refractive power near the optical axis and a positive peripheral refractive power, the A-mode light beam acts as a convex lens, It is possible to give a function as a concave lens to the B-mode light beam. As a result, it becomes possible to output light that can be used as a substantially parallel light flux with a small divergence angle, which is a composite light flux of the A mode and the B mode, from the second lens group.

Further, by making the refractive power in the vicinity of the optical axis zero, that is, by making the lens have an infinite focus, it is possible to prevent the light flux component along the optical axis of the A mode from diverging due to the effect of the concave lens, and It is possible to prevent the B-mode light flux from converging on the optical axis and diverging due to the effect of the convex lens. In particular,
The power of the first lens group is stopped to such an extent that the B-mode light beam becomes a parallel light beam, and the power of the second lens group mainly causes A
By configuring the mode light fluxes to be parallel light fluxes and preventing the B mode light fluxes from diverging, it is possible to obtain a light flux with a small divergence angle that is a combination of the A mode and B mode light fluxes. That is, a first lens group, which is arranged along the optical axis in front of the point light source and has a positive refractive power that makes the reflected light beam emitted from the reflecting surface almost parallel light beam, and in front of this first lens group. It is arranged, there is no refractive power near the optical axis,
A light output device having a second lens group having a positive refractive power in the periphery can also output a light beam having a small divergence angle, which is a light beam of A mode and B mode.

Therefore, according to the light output device of the present invention,
It is possible to emit a light flux having a small divergence angle, which is a combination of the light flux directly output from the point light source and the light flux reflected by the reflecting surface. Therefore, a light output device such as a light emitting diode, which emits light with a large divergence angle, can be used as a point light source with sufficiently high brightness and can be sufficiently used as a light source for a pointer instead of a semiconductor laser. It becomes possible to provide. The lamp type light emitting diode unit described above is a unit in which the light emitting diode which is a minute light source, the reflector, and the tip lens portion which functions as the first lens group are unitized. Further, according to the present invention, it becomes possible to efficiently concentrate the light emitted from the light emitting diode in a region of several cm on the screen 2-3 m away.

The second lens group can be constructed by combining a plurality of lenses, but it is preferable to employ a compound lens having a central portion having a negative or zero refractive power and a peripheral portion having a positive refractive index. Is the most economical. Further, of the A-mode light flux, the light flux incident on the central portion may have a large divergence angle, so it is desirable to make the size of the central portion sufficiently small. Therefore, the diameter of the central portion is preferably about 30% or less of the lens outer diameter, and more preferably about 20% or less. On the other hand, if the diameter of the central portion is too small, there is a possibility that the B-mode light flux cannot be sufficiently captured. Therefore, the diameter of the central portion is preferably about 1% or more of the lens outer diameter, and more preferably about 3% or more.

Further, if the surface of the compound lens on the point light source side is a flat surface, the cost can be further reduced.

The light output device of the present invention is a projection light source using a light emitting diode, but can project a light beam having a sufficiently small divergence angle. Therefore, when the pointer is used, a focused spot on the screen is sufficiently small, and it is possible to provide a safe and high-performance pointer that does not damage the eyes.

In image projection apparatuses such as liquid crystal projectors, attempts have been made to use light emitting diodes as light sources for illuminating image forming means such as liquid crystal light valves having a diagonal of about 1 inch. . In this case, there is a problem that the light emission amount of the light emitting diodes is smaller than the light emission amount of the conventional bulb lamp and the divergence angle of light is large. As a light source,
It is not easy to efficiently transmit the light from each light emitting diode to the liquid crystal light valve. Further, it is not easy to efficiently transfer from the liquid crystal light valve to the lens system for projection. Therefore, there is a problem that it is not easy to put a light source, which is a collection of a large number of light emitting diodes, into practical use as a light source for an image projection apparatus.

On the other hand, the light output device of the present invention is a projection light source using a light emitting diode, but can project a light beam having a sufficiently small divergence angle. Therefore, by adopting the light output device of the present invention in the image projection device,
It becomes possible to solve the above problems, and it is possible to provide an image projection device capable of projecting a bright and clear image using a light emitting diode.

[0018]

The present invention will be further described below with reference to the drawings. FIG. 4 shows a pointer according to the present invention. The pointer 60 of this example has a tip 61.
A thin light beam 62 is emitted from the screen 69
A point 68 of light can be projected on. Therefore, it is used to point to an explanation point in a presentation or the like. The pointer 60 has an elongated cylindrical housing 65, and a switch 63 for controlling the beam 62 is provided on the outer surface of the housing 60. Inside the housing 65, the projection light source 5 that outputs the beam 62
0 and a battery (dry cell) 64 as a power source are stored. Further, at the exit of the beam 62, an aperture 66 for cutting unnecessary divergent light components is provided.

FIG. 5 shows a schematic structure of the projection light source 50. This projection light source corresponds to the light output device of the present invention, and includes the light emitting diode unit 10 and the compound lens 25 arranged on the emitting side thereof. The light emitting diode unit 10 is the same as that described with reference to FIG. 1, and includes a light emitting diode 12 arranged substantially in the center and a cone-shaped reflecting surface 14 arranged on the rear surface (back surface) of the light emitting diode 12. It has a reflector 13 provided and an electrode 11 for supplying electric power to the light emitting diode 12, and these are covered with a transparent resin 17 to be integrated. The resin on the front surface of the light emitting diode 12 is molded so as to be convex at the tip (front), and this portion functions as the tip convex lens 16, that is, the first lens group 21. Therefore, the light emitting diode 12, which is a minute light source that outputs light with a large divergence angle, can be regarded as a point light source, and the A mode light beam (direct light) and the B mode light beam (reflected light) emitted from the minute light source. Is an optical axis 1 that connects the center 14a of the reflecting surface 14 and the light emitting diode 12.
A compound lens 2 which is emitted forward along 9 and is arranged in the front while being condensed to some extent by a convex lens 16 at the tip.
5 is supplied.

The compound lens 25 is arranged at a position where a B-mode light beam forward by a distance L from the tip of the light emitting diode unit 10 is substantially focused on the optical axis 19. The compound lens 25 has a flat side (rear surface) 25a facing the light emitting diode unit 10, and an exit side, that is, a front surface 25b.
Becomes a convex surface on the exit side, and has a plano-convex lens shape as a whole. However, the lens 2 through which the optical axis 19 passes
The central portion 27 of 0 is recessed so as to be convex toward the light emitting diode unit 10. Therefore, in the compound lens 25 of this example, the peripheral portion 26 is a convex lens region having a convex surface on the emitting side and a positive refractive power, and the central portion 27 is the light emitting diode unit 1.
It is a concave lens region that is convex on the 0 side and has a negative refractive power,
It functions as the second lens group 22 of the present invention.

Therefore, in the light output device 50 of this embodiment, the A-mode light beam emitted from the front surface of the chip 12 is not directly reflected by the cone-shaped reflecting surface 14 but is directly refracted by the front convex lens 16 and projected forward. Is further condensed by the convex lens-shaped peripheral portion 26 of the compound lens 25 to become a parallel light flux. On the other hand, the B-mode light beam emitted from the periphery of the chip 12 and reflected by the conical reflecting surface 14 and then refracted by the tip convex lens 16 and projected forward is caused by the concave lens-shaped central portion 27 of the compound lens 25. , Are converted into parallel light beams along the optical axis 19. Therefore, the compound lens 25 outputs a light flux 55 including the A-mode component and the B-mode component and having a small divergence angle and being almost parallel. Therefore, it is possible to obtain a light flux having a small divergence angle that can be used as the light flux 62 emitted from the pointer 60 shown in FIG. 4 while using the light emitting diode 12 that radially outputs light as a light source.

Of the A-mode light flux, the light flux emitted from the light-emitting diode unit 10 along the optical axis 19 is, together with the B-mode light flux, the central portion 2 of the compound lens 25.
It is incident on 7. Of the A-mode light flux, a light flux that is very close to the optical axis 19 has a central portion 27 of the compound lens 25.
The negative lens has little effect. However, the light flux around it diverges due to the action of the negative lens, and it becomes impossible to focus it into a parallel light flux. Therefore, it is desirable to dispose the compound lens 25 in the vicinity of the focal position where the B-mode light beam is condensed along the optical axis 19 and make the diameter of the central portion 27 as small as possible.

For example, the light emitting diode unit (LED) 10 and the compound lens 25 under the conditions of the following first case.
By combining and, it is possible to configure the light output device 50 that emits the light flux 55 with a divergence angle of a half angle of 1 degree or less. (First Case) Diameter of LED 10 5 mm Shape of Tip Convex Lens 16 Distance from Tip of Aspherical LED 10 to Complex Lens 25 5.5 mm Outer Diameter of Complex Lens 25 9.0 mm Focal Length of Convex Lens Section 24 mm Concave Lens Section 27 Outer diameter 1.5 mm Focal length of concave lens portion -1.3 mm Effective divergence angle (half angle) 1 degree or less Since the divergence angle of the light beam 55 output from the light output device 50 of this first case is 1 degree or less, A spot 68 having a diameter of about 7 cm can be projected on the screen 69 or another wall surface 2 m away. Therefore, this light output device 5
It is possible to provide the pointer 60 using the light emitting diode 12 as a light source by adopting 0 as a projection light source and further installing an aperture 66 for cutting unnecessary light.

Further, by combining the light emitting diode unit (LED) 10 and the compound lens 25 under the condition of the second case below, a light output device 50 for emitting a light beam 55 having a divergence angle of a half angle of 4 degrees or less is obtained. Can be configured. (Second Case) Diameter of LED 10 5 mm Shape of Tip Convex Lens 16 Distance from Tip of Aspherical LED 10 to Complex Lens 25 5.5 mm Outer Diameter of Complex Lens 25 7.0 mm Focal Length of Convex Lens Section 24 mm Concave Lens Section 27 Outer diameter 1.0 mm Focal length of concave lens portion -1.0 mm Effective divergence angle (half angle) 4 degrees or less The divergence angle of the light beam 55 output from the light output device 50 of this second case is also 4 degrees or less and projection illumination. As a light source, the luminous flux is substantially parallel. Therefore, it has sufficient performance as a light source of an image projection device such as a liquid crystal projector.

The single plate type projector 70 shown in FIG.
Is a lighting device 71 in which a plurality of light output devices 50 of this example are arranged in an array or the like to secure a light amount, a liquid crystal light valve 72 that modulates a light beam output from the lighting device 71 to form an image, and a modulation device. A lens system 73 for projecting the generated light flux onto a screen 79 and a control device 74 for controlling the liquid crystal light valve 72 based on image data from a host computer are provided.

By adopting the light output device 50 for outputting a light beam with a small divergence angle of this example, when a plurality of light emitting diode units 10 are arranged in an array to form a lighting device 71, the light is output from the lighting device 71. The divergence angle of the luminous flux is small and the luminous flux is almost parallel. Therefore, it is possible to efficiently irradiate the liquid crystal light valve 72 with a light flux having a large light emission amount using the light emitting diode 12 as a light source. Further, since the divergence angle of the light flux to be applied is small, the divergence angle of the light flux output from the light valve 72 is also small, and the light can be swallowed efficiently by the projection lens 73 and applied to the screen 79. Therefore, the light emitting diode 1
It is possible to provide a projector that can project a bright and clear image on the screen 79 by using the light source 2 as the light source.
The same applies to not only a single-plate type projector but also a three-plate type projector, and further a light valve such as LCoS which is a reflective liquid crystal element and DMD using a micro mirror.

The configuration of the compound lens 25 and the numerical values shown as the first and second cases are merely examples. For example, in the above description, one compound lens 25 constitutes the second lens group 22, but a plurality of lenses constitutes a lens system in which the central portion 27 has a negative power and the peripheral portion 26 has a positive power. be able to. However, it is economical to employ the compound lens 25 as described above, and when the light source is a monochromatic light source such as a light emitting diode, achromatization is not necessary. Therefore, by using the compound lens of a single plate, sufficient optical performance can be obtained. Can be obtained. Further, in the A-mode light flux, the central portion 2 of the compound lens 25
On the contrary, since the divergence angle of the light beam incident on 7 becomes large, it is desirable to make the size of the central portion 27 sufficiently small. In the above case, it is set to be about 30% or less of the lens outer diameter. It is desirable that the lens outer diameter of the central portion 27 be small, and therefore, it is more preferable that it is about 20% or less of the lens outer diameter. On the other hand, if the diameter of the central portion 27 is too small, the B-mode light flux cannot be sufficiently taken in. Therefore, it is desirable that the diameter is within the range of about 1% or more, and further about 3% or more of the lens outer diameter.

Further, in the compound lens 25 of this example, the surface (rear surface) 25a on the side of the light emitting diode unit 10 is constituted by a flat surface, but the rear surface 25a has a convex and concave peripheral portion 26 and / or a central portion 27. It is also possible to employ a compound lens provided. However, in order to project the A-mode light flux forward as efficiently as possible, the position of the compound lens 25 should be as close to the light emitting diode unit 10 as possible, and the size of the concave surface of the central portion 27 should be as small as possible. On the other hand, when the distance is too close, the cross section of the B-mode light beam is sufficiently small and is not completely stopped.
In order to increase the incidence efficiency of the B-mode light beam on the central portion 27, the area of the concave surface of the central portion 27 must be increased,
This means that the area of the peripheral portion 26 becomes small for the A-mode light flux, which causes a reduction in efficiency. Therefore, as the position and shape of the compound lens, the central portion 2 of the compound lens is located at the position where the B-mode light beam is best condensed.
As shown in FIG. 5, the concave surfaces of 7 are arranged.
It is desirable to arrange the central portion 27 so as to be located on the side opposite to the light emitting diode unit 10.

Further, the central portion 27 of the compound lens 25 can be constructed by a plane so that the refracting power is zero, that is, the focal length is infinite. An example thereof is shown in FIG. This light output device 50 includes a light emitting diode 12
A reflector 13 having a cone-shaped reflecting surface 14 arranged on the rear surface (back surface) of the light emitting diode 12, a first lens group 21 arranged in front of the light emitting diode 12, and further arranged in front of it. The second lens group 22 is provided. The first lens group 21 is composed of a single convex lens 23, and has a power for collimating a B-mode light beam, that is, a light beam reflected by a cone-shaped reflecting surface along the optical axis 19. There is. The second lens group 22 is also composed of a single compound lens 25, and the peripheral portion 26 is a convex lens area, and has a power for converting the A-mode light beam slightly condensed by the first lens 23 into a parallel light beam. Is equipped with. On the other hand, the central portion 27 of the compound lens 25 is composed of a surface perpendicular to the optical axis 19, has no power, and allows the B-mode light beam collimated by the first lens 23 to pass therethrough as it is. Has become.

Therefore, the light beam 55 emitted from the light output device 50 also contains the A mode light beam and the B mode light beam and has a small divergence angle. Therefore, like the light output device described above, the pointer 60
It is suitable to be used as a light source of the projector 70.

Further, although the light output device using the light emitting diode as the point light source has been described above, if the light source can be regarded as the point light source in the optical system in which the light output device is adopted, the halogen light source is used as the point light source. The present invention can also be applied to a device that employs another diffused light source such as a lamp. Then, it is possible to provide a light output device capable of outputting a light beam having a small divergence angle and a large light amount, by using a cone type having a simple structure as the reflecting plate.

[0032]

As described above, the light output device of the present invention uses a point light source that emits light having a large divergence angle, and further bundles a plurality of light beams of different modes output from the point light source. The divergence angle is small, and it is possible to output a nearly parallel light beam. Therefore, it is possible to provide a light output device that supplies a light flux with a small divergence angle using a light emitting element, which is a small light source with a large divergence angle, as a light source, instead of a light emitting element with a small divergence angle like a semiconductor laser. . Therefore, according to the present invention, it is possible to provide a light output device applicable to many fields such as a small pointer that does not damage the eyes and a light source of a low power consumption type projector.

[Brief description of drawings]

FIG. 1 is a diagram showing luminous fluxes of several modes output from a light emitting diode unit.

FIG. 2 is an example in which a convex lens is set in front of the light emitting diode unit shown in FIG.

FIG. 3 is an example in which a concave lens is set in front of the light emitting diode unit shown in FIG.

FIG. 4 is a diagram showing a schematic configuration of a pointer of the present invention.

FIG. 5 is a diagram showing an outline of a light output device of the present invention.

FIG. 6 is a diagram showing a schematic configuration of a projector of the invention.

FIG. 7 is a diagram showing another example of the light output device of the present invention.

[Explanation of symbols]

10 Light emitting diode light source 12 Light emitting diode (chip) 14 cone-shaped reflector 16 Tip convex lens 21 First lens group 22 Second lens group 25 compound lens 26 Lens periphery (convex lens area) 27 Center of lens (concave lens area) 50 light output device 60 pointer 70 Projector

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 33/00 H01L 33/00 MF term (reference) 2H087 KA06 LA24 RA01 RA45 TA01 TA03 5F041 AA06 DA12 DA18 DA26 DA43 DA55 DA57 DA77 EE12 EE16 FF11

Claims (9)

[Claims] 1. A point light source, a reflector that forms a cone-shaped reflecting surface on the rear surface of the point light source, and a point in front of the point light source along an optical axis connecting the center of the reflecting surface and the point light source. The first lens group having a positive refractive power, which is arranged, and the second lens group, which is emitted from the reflecting surface and is reflected by the first lens group and which is transmitted through the first lens group, is condensed in the vicinity of the optical axis. The second lens group has a negative or zero refractive power in the vicinity of the optical axis and a positive peripheral refractive power. 2. The light emitting diode unit according to claim 1, comprising a light emitting diode serving as the point light source, the reflector, and a tip lens portion functioning as the first lens group. Light output device. 3. The light output device according to claim 1, wherein the second lens group includes a compound lens having a central portion having a negative or zero refractive power and a peripheral portion having a positive refractive index. 4. The diameter of the central portion according to claim 3,
A light output device having an outer diameter of about 1% to 30% of the compound lens. 5. The light output device according to claim 3, wherein the surface of the compound lens on the side of the point light source is a flat surface. 6. A point light source, a reflector that forms a cone-shaped reflecting surface on the rear surface of the point light source, and in front of the point light source along an optical axis connecting the center of the reflecting surface and the point light source. A first lens group having a positive refracting power, which is arranged to make a reflected light beam emitted from the reflecting surface into a substantially parallel light beam; and a first lens group arranged in front of the first lens group and having a refracting power in the vicinity of the optical axis. And a second lens group whose peripheral refractive power is positive. 7. The light output device according to claim 6, wherein the point light source is a light emitting diode. 8. A pointer having the light output device according to claim 2 or 7, and being capable of pointing to a single point with a light beam emitted from the light output device. 9. An image including the light output device according to claim 1 or 6, an image forming unit that modulates a light beam output from the light output device, and a lens system that projects the modulated light beam onto a screen. Projection device.