JP2000181376A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection type display device capable of enhancing the brightness of a projected picture when plural light sources are used in the device. SOLUTION: A light source device 11 is mounted on this projection type display device. This light source device 11 is provided with a prism 30 as a light synthesizing means and combines light beams from light sources 1a, 1b by making the light beam from the light source 1a to be made incident on the side 30a of one side forming the apex angle of the prism to be reflected on the side 30b of other side and by making it to be emitted from the bottom side 30c of the prism and, moreover, by making the light beam from the light source 1b to be made incident on the side 30b to be reflected on the side 30a of other side and by making it to be emitted from the bottom side 30c. In this case, the prism 30 is made so that angles of incidence θof the light beams with respect to perpendicular lines of respective sides 30a, 30b are set equal to or smaller than 20 deg. and, moreover, the angle of incidence θ' of the light beam entering from the side 30a to the side 30b is set equal to or larger than the critical angle of about 41.8 deg. due to the refractive index of the prism. Thus, since the light beams of respective lamps 1a, 1b are totally reflected to be combined without loss, the brightness of the projected picture is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device such as a liquid crystal projector, and more particularly to a projection type display device which combines and projects illumination light from a plurality of light sources.

[0002]

2. Description of the Related Art In recent years, a liquid crystal projector using a liquid crystal panel has been actively developed with a demand for a small-sized and lightweight display device having a large screen. As is well known, a liquid crystal projector uses a liquid crystal panel as a light valve, and displays an image by changing the transmittance of light from a light source according to a video signal. It is to enlarge and display on the screen by means.

[0003] In general, in such a liquid crystal projector, the larger the screen, the darker it tends to be. In other words, the larger the screen, the more difficult it is to realize a bright screen. Also, when trying to view the projected image in a bright room, the projected image may be difficult to see. For this reason, in order to expand the range of use of the liquid crystal projector, it is desired to improve the brightness, that is, improve the light use efficiency so that a bright image can be projected even on a large screen and can be recognized even in a slightly bright room. .

[0004] In response to such demands, proposals have conventionally been made in which a plurality of light sources are provided in order to further improve the brightness of a screen or in consideration of the case where a lamp as a light source is cut off. ing. FIG. 6 shows a conventional technique based on such a proposal.

FIG. 6 is a schematic diagram showing a light source device used in a conventional liquid crystal projector.

[0006] The liquid crystal projector of FIG. 6 employs a light source device 10 comprising a plurality of light sources. In this light source device 10, for example, the illumination light of the two light sources 10 A and 10 B is configured to be combined by a half mirror. As these light sources 10A and 10B, metal halide lamps and the like constituted by lamps 1a and 1b for emitting light and reflectors 2a and 2b for reflecting light emitted from these lamps 1a and 1b are used. The illumination light from these light sources 10A and 10B is applied to the half mirror 11.

The half mirror 11 transmits the light of the lamp 1a and reflects the light of the other lamp 1b, and combines and irradiates the lights of the two lamps 1a and 1b. The combined light combined by the half mirror 11 is narrowed down by a condenser lens or a fly-eye lens 12, and then irradiates a light valve element such as a liquid crystal panel (not shown) to project an image formed on the light valve element. The projection is enlarged.

By the way, in consideration of the light use efficiency of the projection type display device, the above-described conventional light sources (for example, two light sources) are used.
In a device in which the illumination light from the light source is combined by a half mirror, if the light amount of one light source is I, the combined light amount is also a maximum I. However, assuming that one of the two lamps is cut off due to some influence, for example, the light amount at that time becomes a maximum of I / 2. In other words, even if two light sources are used, the illumination light from these light sources is combined by a half-mirror, so there is a large loss of light, and as a result, the projected screen is not bright and one of the lamps is cut off. However, only half the brightness of a single lamp can be achieved. That is, there is a problem that the light use efficiency cannot be improved.

[0009]

As described above, in a conventional projection type display device in which illumination light from a plurality of light sources (two light sources) is combined by a half mirror, the light amount of one light source per light is assumed to be I. In this case, the combined light amount becomes the maximum I, and 2
The light quantity when one of the lamps is cut off is a maximum of I / 2. Therefore, even if two light sources are used, the projection screen does not become bright, and even if one of the lamps is cut off, the brightness becomes only half of the brightness of one lamp, thereby improving the light use efficiency. There was a problem that it was not possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a projection display device capable of improving the brightness of a projection screen when a plurality of light sources are used.

[0011]

According to the present invention, there is provided a projection display device, comprising: a light combining means for combining and outputting light from a plurality of light sources; and irradiating the light output from the light combining means to a light valve element. A projection type display device comprising: means for projecting an image formed by the light valve element, wherein the light combining means faces the first side and the second side forming an apex angle, and the apex angle. The prism includes a triangular prism having a base, and light from a first light source is incident on the first side from outside the prism, reflected by a second side in the prism, and emitted from the base. At the same time, the light from the second light source is made incident on the second side from outside the prism, reflected by the first side in the prism and emitted from the bottom side, and from the first and second light sources. Combines the incident light and outputs it It is characterized in.

According to the present invention, the light from the first light source is made incident on the first side forming the apex angle of the prism, reflected on the second side and emitted from the bottom side of the prism. Light from the light source is incident on the second side;
The light from the plurality of light sources is efficiently combined by providing a triangular prism that combines the light from the first and second light sources so that the light is reflected by the side and emitted from the bottom side of the prism. And the brightness of the projection screen can be improved.

[0013]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a projection type display device according to the present invention, and showing a light source device 11 employed in the device for synthesizing light from a plurality of light sources.

In the present embodiment, in order to use light from a plurality of light sources without loss, a light combining means such as a prism is employed to improve light use efficiency.

In the light source device 11 shown in FIG.
The illumination light from the light sources 11A and 11B is combined by a triangular prism 30 as a light combining means. As these light sources 11A and 11B, metal halide lamps and the like constituted by lamps 1a and 1b emitting light and reflectors 2a and 2b respectively reflecting light emitted from these lamps 1a and 1b are used. . The illumination light from these light sources 11A and 11B
Is irradiated.

The prism 30 is connected to these light sources 11A, 1A.
1B (the lamps 1a and 1b) are combined and emitted. The combined light combined by the prism 30 is narrowed down by a condenser lens or a fly-eye lens 12 as an optical system lens, and then not shown. A light valve element such as a liquid crystal panel is irradiated, and an image formed on the light valve element is enlarged and projected by a projection lens.

The prism 30 is formed in a triangular shape as shown in FIG. 1, and is combined with the two sides 30a and 30b through which light from each of the lamps 1a and 1b is incident by the light combining action of the prism 30. 3 that irradiates the condenser lens or fly-eye lens 12 with the
0c.

In the prism 30, as shown in the figure, light from the lamp 1a is made incident on one side 30a forming the apex angle of the prism 30, reflected by the other side 30b in the prism, and emitted from the bottom 30c. On the other hand, the light from the light source 1b is made incident on the side 30b, reflected by the side 30a in the prism, and emitted from the bottom 30c. In this case, it is important that the light emitted from the base 30c be parallel to the perpendicular of the base 30c.

In order to emit the combined light from each of the lamps 1a and 1b in parallel with the perpendicular to the bottom 30c of the prism 30,
The positioning of the lamps 1a and 1b with respect to the prism 30, that is, the incident angles θ and θ ′ of the light from the lamps 1a and 1b with respect to the sides 30a and 30b of the prism 30 are important.

The setting conditions of the lamps 1a and 1b for efficiently combining the light from the lamps 1a and 1b will be described with reference to FIG.

FIG. 2 shows the transmittance characteristics of the light from the light sources 1a and 1b incident on the sides 30a and 30b forming the apex angle of the prism 30 in FIG. 1 with respect to the incident angle θ.
Refractive index n1 of medium outside prism 30, prism 30
Is a case where the refractive index n2 is 1.5. The vertical axis shown in FIG. 2 represents the transmittance T, and the horizontal axis represents the sides 30a and 30.
3B shows an incident angle θ of light from the light sources 1a and 1b incident on the light incident point b. Note that the incident angle θ is an incident angle with respect to a perpendicular (a broken line in FIG. 1) of the sides 30a and 30b.

As shown in FIG. 2, P having a high transmittance
For the polarization Tp (denoted by the dashed line), the incident angle θ is 60
When the angle exceeds about 0 °, the transmittance T gradually decreases. However, when the angle is within 20 °, the transmittance T always becomes 95% or more. In addition, S-polarized light Ts with low transmittance (denoted by wavy lines)
When the incident angle θ exceeds 20 °, the transmittance T gradually decreases. However, when the incident angle θ is within 20 °, the transmittance T always becomes 95% or more as in the case of the P-polarized light.

That is, if the incident angle θ is within 20 °, the S-polarized light can always maintain a high transmittance of 95% or more like the P-polarized light. As a whole (T (P + S): described by a solid line), if the incident angle θ is set within 20 °, a high transmittance characteristic of 95% or more can be obtained even for S-polarized light whose transmittance is low. Become.

In this embodiment, the lamp 1a
Is incident on the side 30a of the prism 30, then is incident on the opposite side 30b and is reflected toward the bottom side 30c. If the incident angle of the light incident from the side 30a toward the side 30b is θ ′, The incident angle θ ′ is set to be equal to or greater than the critical angle determined by the refractive index, for example, equal to or greater than about 41.8 °. Thus, light incident from the side 30a to the side 30b can be totally reflected, and parallel light is emitted from the bottom side 30c without loss. (The incident angle θ ′ is the angle of incidence with respect to the perpendicular to the side 30b.) Similarly, the light from the lamp 1b is incident on the side 30b of the prism 30, then is incident on the opposite side 30a, and is incident on the base 30c. The incident angle θ ′ of the light that is reflected toward the side 30b from the side 30b is also set to a critical angle of about 41.8 ° or more due to the refractive index.

Therefore, as described above, the prism 30
, And the incident angles of the light sources 1a and 1b, respectively, make it possible to efficiently combine the light from the plurality of light sources 1a and 1b, improve the light use efficiency, and increase the brightness of the projection screen. Can be further improved.

Next, the overall configuration of a projection type display device employing the above light source device 11 will be described in detail with reference to FIG.

FIG. 3 is a configuration diagram when the light source device 11 shown in FIG. 1 is mounted on a three-panel liquid crystal projector.

The three-panel liquid crystal projector in FIG. 3 is provided with a light source device 11 shown in FIG. As described above, the light source device 11 efficiently combines the light from each of the lamps 1a and 1b without loss. The combined light is narrowed down by a condenser lens or a fly-eye lens 12 as an optical system lens, and a liquid crystal element is formed. To be irradiated.

The light from the light source device 11 is a UV light (not shown).
-IR light and ultraviolet light are removed by an IR filter, etc.
Only the visible light component is emitted, and this visible light is applied to the dichroic mirror 13a. This dichroic mirror 13
“a” reflects only the B light of the irradiation light, and transmits the R light and the G light.

After the B light is reflected by the total reflection mirror 14a,
The light passes through the condenser lens 15a and is incident on the B LCD panel (liquid crystal display panel) 16a. In this case, the condenser lens 1
5a has an optical characteristic of narrowing down the light so that the transmitted light of the B LCD panel 16a efficiently enters the entrance pupil of the projection lens 17. The R light of other colors shown in the figure,
The condenser lenses 15b and 15c provided corresponding to the G light also have similar optical characteristics.

The B image light transmitted through the B LCD panel 16a transmits through the dichroic mirrors 13c and 13e.
The projection lens 17 is irradiated together with the R and G image light.

On the other hand, as for the R light and the G light, only the G light is reflected by the dichroic mirror 13b, and the reflected G light is reflected.
The light passes through the condenser lens 15b, and the G LCD panel 16
b. The G image light transmitted through the G LCD panel 16b is reflected by the dichroic mirror 13c,
After passing through the dichroic mirror 13e together with the B image light, the light is applied to the projection lens 17.

The R light transmitted through the dichroic mirror 13b passes through the condenser lens 15c and then enters the R LCD panel 16c. The R image light transmitted through the R LCD panel 16c is reflected by the total reflection mirror 14b, and further reflected by the dichroic mirror 13e, so that the projection lens 17 is irradiated together with the B and G image lights.

Accordingly, each of the R, G, and B image lights is transmitted to the dichroic mirror 1 by the optical member.
After being synthesized by 3e, the image is enlarged and projected on a screen 18, a wall, or the like by the projection lens 17, whereby a projected image based on the input video source is displayed. The brightness of the projected image is extremely bright because parallel light obtained by efficiently combining light from the plurality of lamps shown in FIG. 1 is taken in.

In this embodiment, the case where the light source device 11 is adopted in the three-panel type liquid crystal projector has been described. However, the present invention is not limited to this, and aims at improving light use efficiency. It can be applied to any projection type display device.

Although the present invention has been described with respect to an example in which light from a plurality of light sources is efficiently combined using the prism 30, the use of a prism sheet to which this technique is applied allows the entire projection type display device to be combined. It is also possible to reduce the weight. Such an embodiment is shown in FIGS.

4 and 5 show another embodiment of the projection type display device according to the present invention. FIG. 4 is a structural view showing an improved light source device, and FIG. 5 is a prism of FIG. It is an expanded sectional view of a sheet. 4 and 5, the same components as those of the apparatus shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. Only different portions will be described.

The present embodiment is different from the above-described embodiment in that a light source device 20 having a prism sheet 31 is used as a light combining means for combining light from a plurality of light sources.

The light source device 20 according to the present embodiment includes:
As shown in FIG. 4, a prism sheet 3 for synthesizing light from each of the lamps 1a and 1b is provided at a predetermined position on the incident side of a condenser lens or fly-eye lens 12 as an optical system lens.
1 is provided.

The prism sheet 31 has the same light combining function as the prism 30 (see FIG. 1) in the above-described embodiment, and has a shape in which a number of micro prisms are arranged side by side as shown in FIG. Then, an incident surface 31a into which light from the light source 1a enters and an incident surface 31b into which light from the light source 1b enters are continuously formed, and the combined light (parallel light) obtained by combining the lights from the lamps 1a and 1b by these prism shapes. And an emission surface 31c for emitting light. Further, the prism shape of the prism sheet 31 is formed such that the incident angle θ and the incident angle θ ′ of the light satisfy the same setting conditions as in the above embodiment.

As a result, the light source device 20 has the same light synthesizing action as the prism 30 in the above-described embodiment, so that it is possible to obtain the same effects as in the above-described embodiment. Since the sheet 31 is lighter than the prism 30, it is possible to further reduce the weight when applied to a projection display device.

In the present embodiment, the positioning of the plurality of light sources 11A and 11B can be performed by forming a kit for mounting these light sources in advance so as to satisfy the above-described setting conditions. This can be easily performed even when assembling the light source described above, which greatly contributes to reduction in manufacturing cost.

[0043]

As described above, according to the present invention,
By using a prism as a light combining means for optically combining the light of a plurality of light source lamps, light from a plurality of light sources can be efficiently combined and the brightness of a projection screen can be improved. can get.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a projection type display according to the present invention, and showing a light source device employed in the device.

FIG. 2 is a characteristic diagram showing transmittance of a prism in FIG.

FIG. 3 is a configuration diagram showing a liquid crystal projector when the present invention is applied to a three-panel liquid crystal projector.

FIG. 4 is a configuration diagram showing a second embodiment of the projection type display device according to the present invention, and showing a light source device employed in the device.

FIG. 5 is an enlarged sectional view of the prism sheet shown in FIG.

FIG. 6 is a configuration diagram showing a light source device employed in a conventional projection display device.

[Explanation of symbols]

1a, 1b light source, 2a, 2b reflector, 11, 20 light source device, 11A first light source, 11B second light source, 12 optical lens (condenser lens or fly-eye lens) 30 prism 31 ... Prism sheet (photosynthesis means).

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hisayuki Mihara 3-3-9, Shimbashi, Minato-ku, Tokyo F-term (reference) in Toshiba AV EE Co., Ltd. 2H088 EA14 HA13 HA23 HA25 HA28 KA05 MA06 MA20 5C060 BA04 BA08 BC05 EA00 GA01 GB02 GB06 HC01 HC09 HC19 HC24 HD00 JA11 JB06 5G435 AA03 BB12 BB17 CC12 DD02 DD05 FF03 FF07 GG02 GG03 GG04 GG08 GG26 GG28 GG46 LL15

Claims (3)

[Claims] 1. A light combining means for combining and outputting light from a plurality of light sources, irradiating the light output from the light combining means to a light valve element, and projecting an image formed by the light valve element. Wherein the light combining means includes a triangular prism having a first side and a second side forming an apex angle, and a bottom side facing the apex angle; Light from the light source is incident on the first side from outside of the prism, is reflected by a second side in the prism and is emitted from the bottom side, and light from the second light source is , The light is incident on the second side from outside of the prism, is reflected on the first side in the prism, is emitted from the bottom side, and the light incident from the first and second light sources is combined and output. A projection type display device characterized by the above-mentioned. 2. An incident angle of light from the first and second light sources with respect to a perpendicular to the first and second sides of the prism when the refractive index of the prism is about 1.5. And the incident angle of a light beam from the first side to the second side or the second side to the first side with respect to a perpendicular to the second or first side is greater than or equal to a critical angle. The projection type display device is set so that total reflection is performed and light is emitted in parallel with a perpendicular line at the bottom of the prism. 3. The projection display device according to claim 1, wherein the light combining means is a prism sheet having a plurality of the prisms.