JPH0515036U - Projector - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a projection device having a simple structure and capable of appropriately adjusting the light amount during projection. [Arrangement] A light amount adjusting means capable of reducing the light amount of the light source is provided in an optical path between a light source and a projection surface such as a screen to realize an accurate light amount adjustment of a light flux irradiating the projection surface. Projection device.

Description

[Detailed description of the device]

[0001]

【Technical field】

 The present invention relates to a projection device that projects an image to be projected by a light source onto a projection surface via a projection lens.

[0002]

[Prior art and its problems]

 In this type of projection device, for example, a liquid crystal projector, it is possible to adjust the light amount by changing the voltage supplied to the light source of the projector. However, the light source used for the projection device such as the liquid crystal projector is generally a discharge lamp type such as a metal halide lamp or a xenon lamp, and these do not discharge unless a voltage is supplied above a certain level, so that the light amount is adjusted. Even if it does, its usable current width is extremely narrowed. Therefore, with such a light quantity adjusting means, the light quantity cannot be largely changed even though it has a complicated device for voltage adjustment.

Further, there are some lamps that use a halogen lamp as a light source instead of a metal halide lamp, a xenon lamp, etc. According to this, the color temperature changes with a change in voltage, and the color changes, etc. It causes the inconvenience.

[0004]

[The purpose of the device]

 The present invention has been made in view of the above circumstances, and an object thereof is to provide a projection device having a simple configuration and capable of accurately adjusting the light amount during projection.

[0005]

[Outline of the device]

 The present invention relates to a projection device for projecting an image to be projected by a light source onto a projection surface through a projection lens, wherein the light amount of the light source is in an optical path between the light source and the projection surface. It is characterized in that a light quantity adjusting means capable of reducing the light quantity is provided.

[0006]

Embodiments The present invention will be described below with reference to illustrated embodiments. FIG. 1 shows a liquid crystal projector 29 to which the present invention is applied. A parallel light flux emitted from a light source 10 that emits white illumination light is reflected by a cold mirror 11, and then an R dichroic mirror 12 and a B dichroic mirror 13 are reflected. Reflected and separated by.

The R dichroic mirror 12 reflects only the R (red) component, and the reflected light is reflected by the aluminum mirror 14 and then enters the R liquid crystal unit 15. The light flux emitted from the R liquid crystal unit 15 passes through a B dichroic mirror 16 that transmits the R component and a G dichroic mirror 17 that transmits the B (blue) component and the R component, and then enters a projection lens 18.

The B dichroic mirror 13 reflects only the B component, and the reflected light enters the B liquid crystal unit 20. The light flux emitted from the B liquid crystal unit 20 is reflected by the B dichroic mirror 16, passes through the G dichroic mirror 17, and then enters the projection lens 18.

On the other hand, the luminous flux transmitted through the R dichroic mirror 12 and the B dichroic mirror 13 enters the G (green) liquid crystal unit 21, is reflected by the aluminum mirror 22 and the G dichroic mirror 17, and is then reflected by the projection lens 18. Incident.

The R liquid crystal unit 15 has an R liquid crystal panel 15P and a condenser lens 15L arranged on the emission side of the R liquid crystal panel 15P. Similarly, the B liquid crystal unit 20 has a B liquid crystal panel 20P and a condenser lens 20L arranged on the exit side of the B liquid crystal panel 20P. The G liquid crystal unit 21 includes a G liquid crystal panel 21P and this G liquid crystal panel 21P. It has a condenser lens 21L arranged on the emission side of the panel 21P. The R liquid crystal panel 15P outputs red image information of a color image to be projected, the B liquid crystal panel 20P outputs blue image information, and the G liquid crystal panel 21P outputs green image information. Then, these pieces of image information are superposed by the above optical system, and are projected on the screen (projected surface) 28 in front of the projection lens 18 through the projection lens 18.

The condenser lenses 15L, 20L and 21L are arranged on the emission sides of the liquid crystal panels 15P, 20P and 21P, respectively. That is, the collimated light flux from the light source 10 is incident on the condenser lenses 15L, 20L, and 21L, and therefore, these do not cause the transmittance change (decrease) depending on the angle of the light rays. Further, these condenser lenses 15L, 20L and 21L focus the light fluxes transmitted through the corresponding liquid crystal panels 15P, 20P and 21P on the pupils of the projection lens 18, respectively.

Between the projection lens 18 and the G dichroic mirror 17, a variable diaphragm (light quantity adjusting means) 32 having the optical axis O of the projection lens 18 at its center is provided. The variable diaphragm 32 can change the diaphragm diameter by driving a drive motor (not shown) to increase or decrease the amount of light of the passing light flux. A controller 31 is connected to the variable diaphragm 32. The controller 31 rotates the drive motor in the forward and reverse directions based on the operation of the light amount increasing / decreasing operation buttons 35 and 36 provided outside the liquid crystal projector 29, and switches the diaphragm diameter between large and small.

Therefore, when the large liquid crystal projector 29 is projecting on the screen 28 in front, if the light amount increasing / decreasing operation buttons 35 and 36 are appropriately operated, the diameter of the variable diaphragm 32 is appropriately changed by the controller 31 based on this. Therefore, it is possible to freely change the light amount of the light flux emitted from the projection lens 18 and view the projected image with desired brightness.

Furthermore, since the depth of focus can be increased by changing the aperture diameter of the variable aperture 32, it is possible to deal with shaking of the screen 28 during projection. Further, since the light flux is narrowed to be dimmed by changing the aperture diameter, there is no inconvenience such as deterioration in gradation and color reproducibility as compared with the case where the voltage supplied to the light source 10 is changed. Instead, the amount of light can be changed in a wide range.

Although the variable diaphragm 32 is provided between the projection lens 18 and the light source 13 in this embodiment, the light quantity adjusting means such as the variable diaphragm 32 is essential in the optical path from the light source 10 to the screen 28. Therefore, it may be provided between the dichroic mirror 17 and the projection lens 18 as in this embodiment, or the front portion of the projection lens 18, that is, the projection lens 18 and the screen 28. You may provide in between. When the projection lens 18 is composed of a plurality of lenses, a light amount adjusting means such as the variable diaphragm 32 may be provided between the plurality of lenses.

In the present embodiment, the variable diaphragm 32 is driven to change the diaphragm diameter by a command from the controller 31 based on the operation of the light amount increasing / decreasing operation buttons 35 and 36. However, the variable diaphragm 32 is changed to, for example, a rotating operation ring. The variable aperture 32 may be operated in conjunction with each other by manually operating the rotary operation ring to change the aperture diameter. Further, the light amount adjusting means may have a structure in which, instead of the variable diaphragm 32, diaphragms having different diaphragm diameters are advanced and retracted in the optical path to the projection lens 18. This diaphragm does not necessarily have to be circular, but may have a shape such as a rectangle or a polygon depending on how the amount of light (light flux) is changed.

Further, instead of changing the aperture diameter in the optical path to the projection lens 18, the ND filter is moved forward and backward in the optical path by a command from the controller 31 based on the operation of the light amount increasing / decreasing operation buttons 35 and 36. You may adjust. The advance / retreat of the ND filter may be configured to be performed manually without depending on the command from the controller 31. Further, instead of the variable diaphragm 32, a liquid crystal unit is arranged at the same position, and the liquid crystal density is changed so as to approach the black level by a command from the controller 31 based on the operation of the light amount increasing / decreasing operation buttons 35 and 36, and The light amount may be increased or decreased by increasing or decreasing the transmittance.

In the present embodiment, the present invention is applied to the liquid crystal projector 29 which is a color projector, but the present invention may be applied to a projector of a type that projects a monochrome image.

[0019]

[Effect of the device]

 As described above, according to the projection device of the present invention, a simple structure is simply provided in the optical path between the light source and the projection surface, and the light quantity adjusting means for reducing the light quantity is provided. It is possible to realize accurate light amount adjustment. As a result, the image projected on the projection surface can be viewed with desired brightness. Moreover, since no adjustment method such as changing the supply voltage to the light source is taken, there is no problem such as deterioration of gradation and color reproducibility.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical system showing an example of a projection apparatus to which the present invention is applied.

[Explanation of symbols]

 10 light source 12 13 16 17 dichroic mirror 15 20 21 liquid crystal unit 15P 20P 21P liquid crystal panel 15L 20L 21L condenser lens 18 projection lens 28 screen (projection surface) 29 liquid crystal projector 31 controller 32 variable aperture (light quantity adjusting means) 35 36 light quantity increase / decrease Manual operation button

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Iizuka 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Kogaku Kogyo Co., Ltd.

Claims (4)

[Scope of utility model registration request] 1. A projection device for projecting an image to be projected by a light source onto a projection surface via a projection lens, wherein a light amount of the light source is reduced in an optical path between the light source and the projection surface. A projection device, which is provided with a light amount adjusting means capable of performing the above. 2. The projection device according to claim 1, wherein the light amount adjusting means is a diaphragm that is located in the optical path and shields a part of the light beam. 3. The projection device according to claim 1, wherein the light amount adjusting means has an ND filter that moves forward and backward in the optical path. 4. The projection apparatus according to claim 1, wherein the light amount adjusting means has a liquid crystal unit interposed in the optical path and capable of reducing the amount of transmitted light by changing the liquid crystal concentration.