JP2000347589A - Illuminating device for projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an illuminating device for a projector which produces enough light quantity for illumination by using a projector light source lamp which is easily available and has low output power. SOLUTION: The device is equipped with a first illumination unit 11 and second illumination unit 12 each having a light source lamp 1, reflector 2 and lens array 13 to divide the light reflected by the reflector 2 in one direction into a plurality of light beams and to condense the beams, and a stripe reflection mirror 14 having light-transmitting regions and reflection regions alternately repeated. The light beams from the first illumination unit 11 are condensed onto the light-transmitting regions of the stripe reflection mirror 14 to pass through the stripe reflection mirror 14, while the light beams from the second illumination unit 12 are condensed to the reflection regions to be reflected to the same direction as the light beams from the first illumination unit 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device used for a device for enlarging and projecting an image, such as a liquid crystal projector and a slide projector.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to the drawings. FIG. 14 is a diagram showing a basic configuration of a liquid crystal projector using a conventional lighting device. One light source lamp 1 is provided. Light emitted from the light source lamp 1 is reflected by a reflector 2 having a parabolic surface to form a substantially parallel light flux, which is condensed by a condenser lens 3 to form a liquid crystal panel 4. Irradiation is performed, and the formed image is enlarged and projected on a screen 6 by a projection lens 5.

[0003]

If the brightness of the projected image is insufficient, the color reproducibility and the contrast are reduced and the image becomes unclear. In such a case, the brightness of the indoor lighting is reduced or a special image is produced. You have to use a screen. In order to avoid this, it is necessary to use a projector having a lighting device capable of obtaining a sufficient amount of light. However, ultra-high pressure mercury lamps and metal halide lamps, which are optimal as light sources for projectors because they are close to a point light source and emit a large amount of light per power consumption, have a limited life span when trying to obtain a sufficiently large light output. There was a problem that it became shorter. A xenon lamp is a long-life light source lamp that outputs a large amount of light. However, the amount of emitted light per power consumption is less than half that of the lamp, and further, the lighting circuit and the lamp are significantly increased in cost. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and to provide a projector illuminating apparatus which uses a low-output projector light source lamp which is easily available and which has a greatly increased illumination light quantity as compared with the related art. Aim.

[0005]

In order to achieve this object, according to the present invention, a light source lamp, a reflector for reflecting light emitted from the light source lamp in the same direction, and a light reflected by the reflector are converted into a plurality of light fluxes. A first illumination unit and a second illumination unit each having a lens array for splitting and condensing light;
The first lighting unit, the second lighting unit, and the striped reflecting mirror have a striped reflecting mirror having a light-transmitting area and a reflecting area alternately and repeatedly. A light beam from the first lighting unit is condensed on a light-transmitting area of the striped reflecting mirror and passes through the striped reflecting mirror, and a light beam from the second lighting unit is transmitted to the reflecting area of the striped reflecting mirror. The projector illuminator is arranged so that the light is condensed and reflected by the striped reflecting mirror in the same direction as the light beam from the first illumination unit.

That is, light from two light source lamps is efficiently superimposed, and a light amount nearly twice as large as that of a lighting device having only one light source lamp can be obtained. However, it is possible to easily obtain a lighting device having a sufficient light amount for a projector.

Further, in the present invention, the first lighting unit and the second lighting unit are a projector lighting device having two lens arrays constituting an optical integrator.

That is, the loss of the amount of illumination light is reduced, and the illuminance distribution is made more uniform.

Further, in the present invention, the first illumination unit and the second illumination unit are a projector illumination device having a polarization conversion element for aligning the polarization direction of light emitted from the lens array.

That is, in the case of a liquid crystal projector, if the direction of the polarization of the randomly polarized light is set in advance to a direction in which the absorption by the incident side polarizer of the liquid crystal panel is small, the light utilization efficiency in the liquid crystal panel is improved. Get higher.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

[First Embodiment] FIG. 1 is a sectional view showing the structure of the first embodiment of the present invention, and FIG. 2 is a perspective view showing the structure of the first embodiment of the present invention. Each of the first lighting unit 11 and the second lighting unit 12 includes a light source lamp 1, a reflector 2, and a lens array 13. The light source lamp 1 is an ultra-high pressure mercury lamp, a metal halide lamp, or the like. The reflector 2 has a reflecting surface formed of a paraboloid, and reflects divergent light emitted by the light source lamp 1 disposed at a specific position in the same direction to form a substantially parallel light flux. Lens array 13
Is a matrix in which a plurality of rectangular unit lenses 13a of the same dimensions are arranged in a matrix on the same plane. As shown in FIG. 3, an incident parallel light beam is divided into the same number of light beams as the unit lenses 13a and collected. Light up.

The first lighting unit 11 and the second lighting unit 12 are arranged such that a plurality of light beams from both intersect as a light beam group at a position where a plurality of light beams from both are condensed. The rows of light beams from the first lighting unit 11 and the rows of light beams from the second lighting unit 12 are arranged so as to be staggered at equal intervals in a direction perpendicular to their optical paths. That is, the vertical position is the first position.
Between the illumination unit 11 and the second illumination unit 12 by half the vertical pitch at the converging point of the divided light flux,
It is out of alignment.

The striped reflecting mirror 14 is a plane mirror in which light transmitting areas 14a and reflecting areas 14b are alternately provided. FIG. 4 shows an example of the strip-shaped light-transmitting region 14a having a width which is half the vertical pitch at the converging point of the plurality of light beams from the two illumination units 11 and 12, and has the same width. The stripe-shaped reflection regions 14b are alternately arranged to form a stripe shape.

The striped reflecting mirror 14 is located at a position where the light flux groups from both the first lighting unit 11 and the second lighting unit 12 intersect so that both light paths are plane-symmetric with respect to the reflecting surface. Are located in Therefore, when both optical paths intersect at a right angle, both optical paths are at 45 ° to the reflecting surface of the striped reflecting mirror 14. The striped reflector 14 further transmits the light from the first lighting unit 11 through the plurality of light-transmitting regions 14a, and the second lighting unit 1
2 so that the luminous flux from 2 is reflected by the reflection area 14b.
The vertical position has been adjusted.

In a liquid crystal projector using such an illuminating device, all light beams from the first illuminating unit 11 pass through the translucent area 14a of the striped reflecting mirror 14 and are transmitted from the second illuminating unit 12. All the light beams are reflected by the reflection area 14b of the striped reflection mirror 14, and travel in the same direction as the light from the first illumination unit 11. These are condensed by the condensing lens 3 and illuminate the liquid crystal panel 4 to form an image, and this image is enlarged and projected on the screen 6 by the projection lens 5. Since the lights of the two light source lamps 1 are efficiently superimposed, a light amount almost twice as large as that of a conventional lighting device having only one light source lamp 1 can be obtained.

Incidentally, the light source lamp 1 is not usually a perfect point light source. For example, in the case of a metal halide lamp, the light emitting portion has a shape that is long in the optical axis direction of the lighting unit.
Therefore, the cross-sectional shape of the light beam divided and condensed by the lens array 13 tends to spread radially as shown in FIG. As a result, the light from the first illumination unit 11 protrudes from the translucent area 14a of the striped reflecting mirror 14, or the second
Light from the illumination unit 12 may protrude from the reflection area 14b of the striped reflection mirror 14, resulting in a loss of light amount. To prevent this, the light-transmitting region 1 of the striped reflector 14
As shown in FIG. 6, the shapes of 4a and the reflection region 14b are
What is necessary is just to deform | transform according to the cross-sectional shape of the condensed light beam.

If the focal lengths of all the unit lenses 13a are the same, the lens array 13 sets the light condensing positions of all the light beams on the stripe-shaped reflecting mirror 14 as shown by the circles in FIG. Cannot match position. If the light beam condensing position largely deviates from the position of the striped reflecting mirror 14, the light beam protrudes from the predetermined translucent area 14a and the reflecting area 14b of the striped reflecting mirror 14 to cause a light amount loss. As shown in the above, it is desirable to change the focal length for each unit lens 13a so that the condensing position of all the light beams coincides with the position of the striped reflecting mirror 14.

Of course, it is easier to manufacture a lens array if all the unit lenses have the same focal length. When such a lens array is used, if the focal length is set such that the unit lens 13a near the center of the lens array is focused on the position of the striped reflecting mirror 14, loss of light quantity can be suppressed.

In the lighting device of the present invention, two light source lamps 1
, One of the light source lamps 1
May be selectively turned off. This allows
The amount of light can be increased or decreased as needed. Further, lamps having different emission spectra can be combined to adjust the color tone of the projected image, for example, to obtain a good white light by combining a lamp having a strong blue light emission intensity and a lamp having a strong red light emission intensity. In this case, if either one of the light source lamps 1 can be selectively turned off, the color tone can be selected according to the atmosphere of the projected image, the surrounding environment, and the like.

[Second Embodiment] FIG. 8 is a sectional view showing the structure of the second embodiment of the present invention, and FIG. 9 is a perspective view showing the structure of the second embodiment of the present invention. In these drawings, the same components as those in the previous drawings are denoted by the same reference numerals.

Each of the first lighting unit 21 and the second lighting unit 22 includes a light source lamp 1, a reflector 2, a first lens array 23, and a second lens array 24. The focal length of each unit lens 23a of the first lens array 23 is changed according to the distance to the striped reflector 14, and the light flux from all the unit lenses 23a is
It is set so that light is condensed at the position 4. The second lens array 24 is opposed to the first lens array 23 in parallel, and the focal length of each unit lens is the first lens array.
Has a value corresponding to the distance between the lens array 23 and the second lens array 24. Therefore, the first lens array 23 and the second lens array 24 constitute a so-called optical integrator.

The positional relationship between the first lighting unit 21, the second lighting unit 22, and the striped reflecting mirror 14 is the same as that of the first lighting unit 21 described above.
Are the same as those of the lighting unit 11, the second lighting unit 12, and the striped reflecting mirror 14. Therefore, all the light beams from the first lighting unit 21 pass through any of the plurality of light transmitting areas 14a of the striped reflecting mirror 14, and all the light beams from the second lighting unit 22 are striped reflected. The first illumination unit 2 is reflected by any one of the plurality of reflection areas 14 b of the mirror 14.
The light travels in the same direction as the light from 1 and is condensed by the condenser lens 3.

Since the first lens array 23 and the second lens array 24 of the first illumination unit 21 and the second illumination unit 22 constitute a so-called optical integrator, the first embodiment The loss of the amount of illumination light is smaller than in the case of the embodiment, and the illuminance distribution is made uniform.

FIG. 8 shows an example of the overall configuration of a color liquid crystal projector using the above-described illumination device according to the second embodiment of the present invention. Here, unlike FIG. The example of using three sheets is shown. In this case, a color separation optical system and a color synthesis optical system are added. That is, the illumination light that has passed through the condenser lens 3 is split into three colors of red, green, and blue by two dichroic mirrors 25, and passes through a reflection mirror 26 and a lens 27. The light is guided to the liquid crystal panels 4 for image display and blue image display, and three-color images are synthesized by the cross dichroic prism 28 to reach the projection lens 5.

This cross dichroic prism 28
Is a combination of four prisms each composed of a dichroic mirror on the surface equivalent to the isosceles of a right-angled isosceles triangular prism.In the portion where the vertices of the four prisms are in contact, light is Because it does not reflect or transmit
This produces dark lines in the projected image. When a lens array in which four unit lenses are arranged in a horizontal direction as shown in FIG. 8 is used, four dark lines are generated at the center of the projected image.

This problem is, as shown in FIG.
The optical axes of the illumination unit 21 and the second illumination unit 22 are shifted in the vertical direction as well as in the horizontal direction, and the light flux from each unit lens of the first illumination unit 21 transmitted through the stripe-shaped reflecting mirror 14 and the stripe This is improved by making the luminous flux from each unit lens of the second illumination unit 22 reflected by the reflection mirror 14 alternate in the horizontal direction. That is,
Although the number of dark lines generated in the projected image is doubled, the difference in brightness between the dark line and the other parts is reduced, so that the dark lines are not noticeable.

[Third Embodiment] FIG. 11 shows a third embodiment of the present invention.
FIG. 12 is a cross-sectional view showing a main part of FIG. 11 in an enlarged manner. In these drawings, the same components as those in the previous drawings are denoted by the same reference numerals. Here, both the first illumination unit 31 and the second illumination unit 32 have a configuration in which a polarization conversion element 35 is added behind the second lens array in the above-described second embodiment.
Thereby, the polarization directions of the illumination light are aligned and the light use efficiency of the liquid crystal panel is increased, so that the projected image can be made brighter than in the second embodiment.

In general, a liquid crystal panel has a structure in which a liquid crystal element is sandwiched between two polarizers. First, the incident side polarizer converts the incident light into linearly polarized light, then the liquid crystal element modulates the light according to the electric signal, and finally, the exit side polarizer,
Either the modulated light or the unmodulated light is transmitted to be emitted light. Since the light emitted from a normal light source is completely random polarized light, half of the light is absorbed by the polarizer on the incident side as it is.

Now, if the direction of the polarization of the randomly polarized light is previously adjusted to a polarization direction in which light absorption by the polarizer on the incident side is low, and this is made incident on the polarizer on the incident side, the light on the incident side can be obtained. Light absorption by the polarizer is greatly reduced, and the light use efficiency of the liquid crystal panel is increased. A polarization conversion element 35 is used as a means for aligning the polarization directions.

The structure and operation will be described below with reference to FIG. The polarization conversion element 35 includes a PBS array (polarization beam splitter array) 36 and a plurality of λ / 2 phase difference plates (half-wave plates) 38. The PBS array 36 includes a plurality of PBSs.
(Polarizing beam splitter) 37 and their reflecting surfaces 37
are tilted by 45 ° with respect to the incident light, and are arranged side by side along the second lens array 34 at a pitch of half the width of the unit lens 34a of the second lens array 34. The λ / 2 retardation plate 38 is provided on the output side of every other PBS 37 and each unit lens 34 of the second lens array 34.
It is arranged on the optical axis a.

The light incident on each unit lens 34a is collected and incident on every other PBS 37 of the PBS array 36. Of the light incident on each PBS 37, the S-wave light is reflected by the reflection surface 37a, and the reflection surface 37a of the adjacent PBS 37
, And is emitted again in the same direction as the incident direction. On the other hand, the P-wave light is transmitted through the reflection surface 37a, and is emitted with the polarization direction rotated by 90 ° by the λ / 2 phase plate 38. That is, light of random polarization passes through the polarization conversion element array 35 and is converted into light having a uniform polarization direction.

In order to apply the above-mentioned polarization conversion means to the present invention, it is necessary to devise the focal length of the first lens array 33. That is, each light beam split by the first lens array 33 needs to be condensed vertically at the position of the PBS array 36, and must be condensed horizontally at the position of the next striped reflecting mirror 14. There is. Therefore, the unit lenses of the first lens array 33 must have different focal lengths in the vertical and horizontal directions.

FIG. 1 shows an example of such a lens array.
As shown in FIG. 3, there is a combination of a cylindrical lens array including a vertically long unit cylindrical lens 33a and a cylindrical lens array including a horizontally long unit cylindrical lens 33b. In this case, the vertically long unit cylindrical lens 33a is
By setting the focal length of each unit lens so that the horizontally long unit cylindrical lens 33b focuses on the position of the striped reflector 14, the vertically long unit cylindrical lens 3
3a focuses in the horizontal direction and focuses on the position of the PBS array 36 in the vertical direction, while the horizontal unit cylindrical lens 33
b focuses light in the vertical direction and forms a long focus in the horizontal direction at the position of the striped reflecting mirror 14.

By using such a first lens array 33, first, vertically condensed light is incident on every other PBS 37 of the PBS array 36 and is converted into linearly polarized light. The light is condensed horizontally and enters the striped reflecting mirror 14. Here, the light beam of the first lighting unit 31 passes through the light-transmitting area 14a of the striped reflecting mirror 14, and the light beam of the second lighting unit 32 is reflected by the reflecting area 14b of the striped reflecting mirror 14, and The light beams are superimposed as light beams traveling in the same direction. Since this light has the same polarization direction, the loss when illuminating the liquid crystal panel is small. Therefore, a large amount of light can be obtained.

The present invention is not limited to the above examples,
Further, various modifications can be made.

[0037]

As described above, according to the present invention,
It is possible to provide a projector illuminating device capable of obtaining a large illuminating light amount by using two easily available low-output light source lamps and efficiently superimposing light from both.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of the first exemplary embodiment of the present invention.

FIG. 3 is a sectional view showing light collection by a lens array.

FIG. 4 is a diagram illustrating an example of a striped reflecting mirror in FIG. 1;

FIG. 5 is a diagram showing an example of a cross-sectional shape of a light beam divided and condensed by a lens array.

FIG. 6 is a diagram showing another example of the striped reflecting mirror in FIG. 1;

FIG. 7 is a diagram showing a positional relationship between a condensing point by a lens array and a striped reflecting mirror.

FIG. 8 is a sectional view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 9 is a perspective view illustrating a configuration of a second exemplary embodiment of the present invention.

FIG. 10 is a sectional view showing an example of the arrangement of two lighting units in FIG.

FIG. 11 is a sectional view showing a configuration of a third exemplary embodiment of the present invention.

12 is an enlarged sectional view of a main part of FIG.

FIG. 13 is a perspective view showing an example of a first lens array in FIG.

FIG. 14 is a diagram showing a basic configuration of a liquid crystal projector using a conventional lighting device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light source lamp 2 reflector 3 condenser lens 4 liquid crystal panel 5 projection lens 6 screen 11 first illumination unit 12 second illumination unit 13 lens array 13a unit lens 14 striped mirror 14a translucent area 14b reflective area 21 first Lighting unit 22 second lighting unit 23 first lens array 23a unit lens 24 second lens array 24a unit lens 25 dichroic mirror 26 reflecting mirror 27 lens 28 cross dichroic prism 31 first lighting unit 32 second lighting Unit 33 First lens array 33a Vertical unit cylindrical lens 33b Horizontal unit cylindrical lens 34 Second lens array 34a Unit lens 35 Polarization conversion element 36 PBS array 37 PBS 37a Reflection surface 38 λ / 2 phase plate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junji Tomita 4-1-1 Kamikadanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu Limited (reference) 2H088 EA12 HA13 HA20 HA21 HA25 HA28 MA06 2H091 FA05Z FA10Z FA11Z FA14Z FA26X FA26Z FA29Z FA41Z FD03 FD22 LA16 MA07 3K042 AA01 AC06 BB03 BC03 5G435 AA03 AA12 BB12 DD07 DD09 FF03 FF05 FF07 GG05 GG08 GG23 LL15

Claims (3)

[Claims] A first light source lamp includes a light source lamp, a reflector that reflects light emitted from the light source lamp in the same direction, and a lens array that divides the light reflected by the reflector into a plurality of light beams and condenses the light beams. An illumination unit, a second illumination unit, and a striped reflector having a translucent area and a reflection area alternately and repeatedly; the first illumination unit, the second illumination unit, and the striped reflector The light beam from the first lighting unit is condensed on a light-transmitting area of the striped reflecting mirror and transmitted through the striped reflecting mirror, and the light beam from the second lighting unit is reflected by the striped reflecting mirror. An illumination device for a projector, wherein the illumination device is arranged so that light is condensed on a reflection area of the mirror and reflected by the stripe-shaped reflection mirror in the same direction as a light beam from the first illumination unit. 2. The illumination device for a projector according to claim 1, wherein each of the first illumination unit and the second illumination unit has two lens arrays constituting an optical integrator. 3. The projector according to claim 1, wherein each of the first illumination unit and the second illumination unit has a polarization conversion element for aligning a polarization direction of light emitted from the lens array. Lighting equipment.