JP2006201428A - LED projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED type projector capable of suppressing brightness unevenness of a projected image, requiring no heat protection measures, and miniaturizing.
An LED light source unit 13 includes an LED 12 that emits visible light that passes through a film surface on which an image to be projected is recorded, and a light control unit 14 uses visible light emitted from the LED light source unit 14 as an optical axis. And a central lens unit 15 that controls the radiation so as to radiate substantially in parallel, and a total reflection unit 16 that condenses the visible light emitted from the LED light source unit 14 so that the reflected light trajectory crosses forward in a substantially total reflection manner. A film holding part 18 for holding the film 19 is disposed between the projection lens 20 and the shortest position from the light control means 14 where the reflected light locus of the total reflection part 16 crosses forward; The projection lens 20 is disposed in the vicinity of the position where the combined light flux from the total reflection portion 16 is most focused, and the image on the film 19 is projected onto the screen 21.
[Selection] Figure 1

Description

  The present invention relates to an LED projector using a light emitting diode as a light source.

  In a projector that projects light onto a projection surface such as a screen by transmitting light through a film on which an image to be projected is recorded, a light bulb such as a halogen lamp or a high-intensity discharge lamp is used as a light source. In addition, there is a slide projector using a light bulb that is small and light, can be easily carried, and can be used in a place without a commercial power supply (see, for example, Patent Document 1). This slide projector is provided with a frame guide passage for passing a slide support frame on which a plurality of photographs to be slid are affixed in a housing, receives light from a light bulb irradiated to photographs on the frame with a mirror, It is projected by a projection lens in a slidable lens support tube and projected onto a screen placed in front of the projection lens.

On the other hand, as a light emitting diode (hereinafter referred to as LED) as a light source of a projection type liquid crystal display device, there is a structure in which uniform light can be emitted using a plurality of LEDs (for example, see Patent Document 2). ). In this projection type liquid crystal display device, the incident surface of the plurality of LEDs on the light guide means and the light exit surface of the light incident on the light guide means are linear or in series, and the light guide is a point light source. Incident light from the LED can be uniformly diffused, and it is possible to display a projection image that is compact and has no unevenness in light intensity.
Registered Utility Model No. 30471152 JP 2004-110062 A

  However, in LED projectors that use halogen lamps or high-intensity discharge lamps as the light source, the infrared radiation emitted from the light source reaches the film surface, so use an inorganic film with high heat resistance, or use infrared radiation light. Reduction of heat insulation is essential. Similarly, for the small portable type disclosed in Patent Document 1, it is necessary to take measures against heat by lighting the bulb. As measures against heat insulation, for example, infrared radiation emitted from a light bulb is removed by an infrared cut filter to suppress heat generation.

  Further, in the projection type liquid crystal display device using a plurality of LEDs disclosed in Patent Document 2, it is necessary to take measures to prevent unevenness in light intensity. For example, a light guiding unit that uniformly diffuses and emits incident light is required, and it is difficult to reduce the size.

  An object of the present invention is to provide an LED projector that can suppress unevenness in brightness of a projected image, does not require a heat-proof measure, and can be miniaturized.

  An LED projector according to a first aspect of the present invention is an LED light source unit that includes a light emitting diode that emits visible light that passes through a film surface on which an image to be projected is recorded; and that emits visible light emitted from the LED light source unit. Light having a central lens unit that is controlled to radiate substantially parallel to the axis, and a total reflection unit that condenses the visible light emitted from the LED light source unit so as to substantially totally reflect and the reflected ray trajectory crosses forward. A control unit; a projection lens that is arranged in the vicinity of a position where the combined light flux from the central lens unit and the total reflection unit is most narrowed; and that projects an image on the film onto a projection plane; reflection of the total reflection unit And a film holding section for holding the film, which is disposed between the shortest position from the light control means where the ray trajectory crosses forward and the projection lens.

  In the present invention and the following invention, the definitions and technical meanings of terms are as follows. The LED light source unit has one light emitting diode (LED) and emits visible light that passes through a film surface on which an image to be projected is recorded.

  The light control means controls and collects light from the LED of the LED light source unit, and includes a central lens unit and a total reflection unit, and the emission surface is formed as a flat surface. The central lens part is a convex lens formed at the central part of the light control means, and controls the visible light emitted from the LED light source part to be emitted almost in parallel with the optical axis and emits it from the emission surface. On the other hand, the total reflection part is a concave reflection surface formed in the peripheral part of the central lens part of the light control means, almost totally reflects the visible light emitted from the LED light source part, and the reflected ray trajectory crosses forward. Condensate like so.

  The projection lens projects an image on the film onto the projection surface, and is disposed in the vicinity of the position where the combined luminous flux from the central lens portion and the total reflection portion of the light control means is most focused. The position where the light beam is most narrowed is a portion where the combined cross-sectional area of the light beam from the central lens portion and the total reflection portion is the smallest.

  The film holding unit holds the film, and is disposed between the projection lens and the shortest position from the light control means where the reflected light ray trajectory of the total reflection unit crosses forward. The shortest position from the light control means that crosses forward is the cross position that is closest to the exit surface of the light control means among the positions where the reflected light ray trajectory from the total reflection portion crosses in front of the light control means.

  An LED projector according to a second aspect of the present invention is an LED light source unit including a light emitting diode that emits visible light passing through a film surface on which an image to be projected is recorded; and forward visible light emitted from the LED light source unit. A central lens portion that radiates substantially uniformly, and a total reflection portion that condenses almost all of the light that has passed through the central lens portion so that the reflected ray trajectory crosses forward, and has an exit surface. And a light control means in which the curvature of the central lens portion and the total reflection portion is set so that the density of the passing light beam is substantially uniform; and the vicinity of the position where the reflected ray trajectory from the total reflection portion is most narrowed A projection lens that projects an image on the film onto a projection surface; and a film holding unit that is disposed in the vicinity of the exit surface of the light control unit and holds the film.

  The central lens portion of the light control means of the present invention is formed, for example, in a hemispherical concave shape in the central portion of the light control means, and radiates visible light emitted from the LEDs of the LED light source portion substantially uniformly forward. The total reflection part is a concave reflection surface formed in the peripheral part of the central lens part, almost totally reflects a part of the radial light transmitted through the central lens part, and the reflected ray locus is in front of the light control means. The light is condensed so as to cross and is emitted from the emission surface. The curvature of the central lens portion and the total reflection portion is set so that the density of the passing light beam is substantially uniform on the exit surface.

  The film holding unit holds the film and is disposed in the vicinity of the light emission surface of the light control means. The projection lens projects an image on the film onto the projection surface, and is disposed in the vicinity of the position where the reflected ray trajectory from the total reflection portion is most reduced. The position where the reflected ray trajectory from the total reflection part is most narrowed is a place where the cross-sectional area of the light beam reflected and synthesized by the total reflection part is the smallest.

  According to the first aspect of the present invention, the film held by the film holding part is incident and transmits the reflected light from the total reflection part without omission, so that it is projected with almost no dark part near the axis. Brightness unevenness of the image can be suppressed. In addition, since the projection lens is arranged at the position where the luminous flux is most focused, the diameter of the projection lens can be reduced and the projection lens can be reduced in size. Further, since an LED is used as the light source, a special infrared cut filter is not necessary and can be configured at low cost.

  According to the invention of claim 2, since the film held by the film holding unit is disposed in the vicinity of the exit surface of the light control means in which the density of the passing light beam is substantially uniform, the brightness unevenness of the projected image Can be suppressed and downsizing can be achieved. Further, similarly to the first aspect, since the diameter of the projection lens can be reduced, the projection lens can be reduced in size, and a special infrared cut filter is not required and can be configured at low cost.

(First embodiment)
FIG. 1 is a configuration diagram of an LED projector according to a first embodiment of the present invention. The LED projector 11 includes an LED light source unit 13 that uses an LED 12 as a light source, and light from the LED 12 of the LED light source unit 13 is controlled and condensed by a light control unit 14. The light control means 14 controls the light collection from the LED 12 of the LED light source unit 11, and includes a central lens unit 15 and a total reflection unit 16. The light exits from the surface 17.

  The film holding unit 18 holds the film 19 on which an image to be projected is recorded. The film holding unit 18 transmits light from the light control unit 14 and projects the light onto the screen 21 that is a projection surface through the projection lens 20.

  FIG. 2 is an explanatory diagram of a light collection state of the light from the LED 12 in the light control unit 14 according to the first embodiment of the present invention. A central lens portion 15 is formed in the central portion of the light control means 14, and a total reflection portion 16 is formed in the peripheral portion of the central lens portion 15. The central lens unit 15 is a convex lens, and the light emitted from the LED 12 toward the periphery of the optical axis is controlled so as to be radiated to substantially parallel light and is emitted from the emission surface 17. On the other hand, the total reflection part 16 is a concave reflection surface, almost totally reflects light emitted in the peripheral direction away from the optical axis of the LED 12 of the LED light source part 13, and the reflected ray locus of the light control means 14 is forward. The light is condensed so as to cross and is emitted from the emission surface 17.

  The reflected light from the total reflection portion 16 is emitted from the emission surface 17 and crosses in front of the light control means 14 as shown in FIG. This cross position differs depending on the exit position from the exit surface 17. The cross position of the light beam emitted from the edge side of the exit surface 17 is far from the exit surface 17, and the cross position of the light beam exited from the center side of the exit surface 17 is Nearer from the exit surface 17. Focusing on the cross position A closest to the exit surface 17 of the light control means 14 among the positions where the light flux from the total reflection section 16 crosses in front of the light control means 14, the film is held at the front position B further on the shortest position A. The part 18 is arranged. That is, the film holding unit 18 is disposed between the shortest position A and the projection lens 20.

  The reason why the film holding portion 18 is arranged at the further forward position B of the shortest position A is that the reflected light from the total reflection portion 16 is incident on the film 19 held by the film holding portion 18 without omission. That is, in the position ahead of the shortest position A, almost all the reflected light rays from the total reflection portion 16 pass, and the reflected light from the total reflection portion 16 can pass through the film 19 without leakage. Thereby, a dark part hardly arises around an axis | shaft and the brightness nonuniformity of the image projected can be suppressed.

  On the other hand, the projection lens 20 is disposed in the vicinity of the position C where the combined light flux from the central lens portion 15 and the total reflection portion 16 of the light control means 14 is most focused. At the position C where the light beam is most focused, the cross-sectional area of the combined light beam from the central lens unit 15 and the total reflection unit 16 is the smallest. The reason why the projection lens is arranged at the position C at which the light beam is most focused is that the cross-sectional area of the light beam is the smallest at the position C, so that the diameter of the projection lens 20 can be reduced and the projection lens 20 can be downsized.

  The distance between the projection lens 20 and the film holding unit 18 is the focal length of the projection lens 20. That is, the shortest distance A at which the light beam of the total reflection unit 16 crosses and the position C at which the light beam is most focused take into consideration the focal length of the projection lens 20 to be used, and the shape of the central lens unit 15 and the total reflection unit 16. To decide.

The LED 12 emits light having a ratio of infrared radiation density to visible light density passing through the surface of the film 19 of 1 or less, or radiation density other than visible light passing through the surface of the film 19 is 100 mW / cm ² or less. Use one. That is, the LED 12 is selected in consideration of the distance between the LED 12 and the film holding unit 18. Thereby, it is not necessary to provide an infrared cut filter in the tube of the light control means 14 and the film holding unit 18.

By using the LED 12 as a light source, direct infrared radiation from the light source can be made small enough to be ignored, so there is no need to take measures against heat. Although the temperature of the entire LED light source unit 13 rises due to the power loss (heat generation) of the LED 12, if the color temperature difference of the LED light source unit 11 reaching the surface of the film 19 is 100K, the heat from the LED 12 reaching the surface of the film 19 Radiation does not exceed 100 mW / cm ² .

On the other hand, if visible light of about 30 lm passes through the surface of the film 19 of 1 cm ² , this light amount corresponds to radiant energy of about 100 mW / cm ² . Moreover, this light quantity is obtained by using LED12 of the current power consumption 1W class. In the future, larger values will be obtained if the efficiency of the LED increases.

Accordingly, the ratio of the infrared radiation density to the visible light density passing through the film 19 surface on which the image to be projected is recorded is 1 or less, and the radiation density other than visible light passing through the film surface from the LED light source unit is 100 mW / LED12 which becomes cm < ² > or less can be prepared easily. For this reason, an infrared cut filter other than visible light, an ultraviolet cut filter, or the like is unnecessary, and the LED projector can be made inexpensive and downsized. The visible light has a wavelength of 380 nm to 680 nm, and the infrared radiation light has a wavelength of over 680 nm. The density is the energy density per unit area, for example, the unit is mW / cm ² .

(Second Embodiment)
FIG. 3 is an explanatory diagram of a light collection state of the light from the LED 12 in the light control unit 14 according to the second embodiment of the present invention. In the second embodiment, the density of the passing light beam is substantially uniform on the exit surface 17 of the light control means 14 as compared to the light control means 14 in the first embodiment shown in FIG. It is.

  The central lens portion 15 of the light control means 14 of the second embodiment is formed in a hemispherical concave shape at the central portion of the light control means 14. The central lens unit 15 receives light from the LED 12 from the concave side of the hemisphere and emits the light almost uniformly forward from the convex side of the hemisphere. That is, the light is uniformly emitted toward the total reflection portion 16 and the emission surface 17. The total reflection portion 16 is a concave reflection surface formed in the peripheral portion of the central lens portion 15. The total reflection portion 16 substantially totally reflects a portion of the radial light transmitted through the central lens portion 15, collects the light so that the light beam crosses in front of the light control means 14, and emits the light from the emission surface 17. In this case, the curvature of the central lens portion 15 and the curvature of the total reflection portion 16 are set such that the density of the passing light flux is substantially uniform on the exit surface 17. Therefore, the density of the passing light beam becomes substantially uniform on the exit surface 17 of the light control means 14.

  The film holding unit 18 that holds the film is disposed at a position D in the vicinity of the emission surface 17 of the light control unit 14. This is to allow the film to transmit light having a substantially uniform density of passing light flux and to suppress unevenness in the brightness of the image projected on the screen (projection surface) 21.

  The projection lens 20 is disposed in the vicinity of the position E where the light beam from the total reflection portion 16 is most focused. The position where the light beam from the total reflection portion 16 is most focused is a portion where the cross-sectional area of the light beam reflected and synthesized by the total reflection portion 16 is the smallest. By arranging the projection lens 20 at this position E, the projection lens is arranged. The diameter of 20 can be reduced, and the light from the light control means 14 enters without leaking. Therefore, the projection lens 20 can be downsized, and the LED projector 11 itself can be downsized.

  Also in this case, since the distance between the projection lens 20 and the film holding unit 18 becomes the focal length of the projection lens 20, the position D in the vicinity of the exit surface 17 (the film holding unit 18 of the film holding unit 18) where the density of the passing light beam becomes substantially uniform. The distance between the installation position) and the position E at which the light flux from the total reflection portion 16 is most reduced determines the shapes of the central lens portion 15 and the total reflection portion 16 in consideration of the focal length of the projection lens 20 to be used. become.

By using the LED 12 as a light source, direct infrared radiation from the light source can be negligibly reduced, so there is no need to provide an infrared cut filter in the tube between the light control means 14 and the film holding unit 18, and the film holding unit 18 can be installed in the vicinity of the exit surface 17 of the light control means 14. As described above, the temperature of the entire LED light source unit 13 rises due to the power loss (heat generation) of the LED 12, but if the color temperature difference of the LED light source unit 11 reaching the vicinity of the emission surface 17 is 100K, the emission surface. 17, the heat radiation from the LED 12 reaching the surface of the film 19 does not exceed 100 mW / cm ² .

  The film 19 held on the film holding unit 18 of the LED projector 11 described above records an image projected on a projection surface such as characters and figures. This film 19 is actually used in the LED projector 11. It is absolutely necessary to use. Therefore, an image creation software medium for supporting the layout of the image to be recorded on the film 19 is supplied attached to the main body of the LED projector 11. Thereby, for example, a film used for projection can be easily created using a personal computer (PC) and a printer, so that convenience is improved.

  In addition, the image creation software attached to the main body of the LED projector 11 has not only an image layout support function but also a function of correcting the distortion of the projected image that inevitably occurs when projecting from an oblique direction. deep.

For example, when the body of the LED projector 11 must be installed in an oblique direction with respect to the projection surface, the recorded image on the film is corrected by the projection image distortion correction function. Thereby, at the time of projection, an image with little distortion can be projected from a place other than a place facing the projection plane. Therefore, restrictions on installation of the main body of the projector 11 are greatly removed.

1 is a configuration diagram of an LED projector according to a first embodiment of the present invention. Explanatory drawing of the condensing state of the light from LED in the light control means in the 1st Embodiment of this invention. Explanatory drawing of the condensing state of the light from LED in the light control means in the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... LED type projector, 12 ... LED, 13 ... LED light source part, 14 ... Light control means, 15 ... Central lens part, 16 ... Total reflection part, 17 ... Output surface, 18 ... Film holding part, 19 ... Film, 20 ... projection lens, 21 ... screen

Claims (2)

An LED light source unit including a light emitting diode that emits visible light passing through a film surface on which an image to be projected is recorded;
A central lens unit that controls the visible light emitted from the LED light source unit to be emitted almost in parallel with the optical axis, and the visible light emitted from the LED light source unit is almost totally reflected so that the reflected light locus crosses forward. A light control means having a total reflection part for condensing light;
A projection lens that is disposed in the vicinity of a position where the combined light flux from the central lens unit and the total reflection unit is most focused, and projects an image on the film onto a projection surface;
A film holding section for holding the film, which is disposed between the projection lens and the shortest position from the light control means where the reflected light locus of the total reflection section crosses forward;
An LED projector characterized by comprising: An LED light source unit including a light emitting diode that emits visible light passing through a film surface on which an image to be projected is recorded;
A central lens unit that emits visible light emitted from the LED light source unit almost uniformly forward, and a part of the light that has passed through the central lens unit is totally reflected so that the reflected ray trajectory crosses forward. And a light control means in which the curvature of the central lens part and the total reflection part is set so that the density of the passing light beam is substantially uniform on the exit surface;
A projection lens that is disposed in the vicinity of a position where the reflected light locus from the total reflection portion is most narrowed and projects an image on the film onto a projection surface;
A film holding unit arranged in the vicinity of the light exit surface of the light control means to hold the film;
An LED projector characterized by comprising:

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