Projection display with a detachable lamp

A projection enabling replacement of its lamp with minimum components. The light source lamp section includes a high-pressure discharge lamp and a metal reflector to which the high-pressure discharge lamp is attached. A plurality of engaging portions are provided on an opening rim of the metal reflector, while engaged portions are provided in a lamp housing section of the body of the projection display. The engaged portions are engaged with the engaging portions. By engaging the plurality of engaging portions of the opening rim with the engaged portions of the lamp housing section, the light source lamp section is secured to the lamp housing section of the body.

The priority application Number JP2006-281214 upon which this Patent application is based is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a projection display, more particularly to a light-source lamp unit used in a projector.

2. Description of the Related Art

Projection displays, such as liquid crystal projectors, are a well-known technique to project enlarged images of letters, figures and so on. Such a projection display uses a lamp unit that is a box case including a high-intensity lamp with a reflecting mirror (reflector) because the lamp in the projection display is required to produce a predetermined light output. A brief description will be made about the structure of a conventional lamp unit and a projector where the lamp unit is set.

FIGS. 14 and 15illustrate the conventional projector:FIG. 14is a perspective view of a lamp unit in schematic form; andFIG. 15is a partially cut-out perspective view of a projector in which the lamp unit is attached.

As shown inFIG. 14, a lamp unit1100having a box case1102includes a high-intensity lamp1104with a reflecting mirror (reflector)1103is detachable from a projector body1110. Such a detachable lamp unit is realized with a pin1105provided on the lamp unit1100and the corresponding plug1116provided in the body. There is no problem to put the pin1105in the body1110and the plug1116on the lamp unit1100.

Attaching the lamp unit1100to the body1110couples the pin1105and the plug1116. The plug1116is electrically connected to a lighting circuit (not shown) provided in the body1110. The lighting circuit starts/lights the lamp1104of the lamp unit1100. There are a cooling fan1117and a cover1111behind and above the lamp unit1100attached in the body1110, respectively.

In the body1110, an optical system having the lamp as a light source and an image modulating means, which is used for controlling the optical system to display images and includes a liquid crystal panel and other components, are provided. Light emitted from the lamp1104passes through the optical system and projection lens1114and is projected onto a screen as an image.

By the way, many of the above-mentioned reflecting mirrors (reflector)1103are generally made of glass. The lamp, as discussed above, is attached to the body1110as a part of the lamp unit1100. Because of this, replacement of the lamp involves replacement of the whole lamp unit1100. An image display device in which an entire lamp unit is attached to the device body is disclosed in Japanese unexamined patent publication No. 2003-280096, for example.

SUMMARY OF THE INVENTION

Should the necessity to replace the high-pressure discharge lamp (burner) of the conventional display devices arise due to breakage or the like, the entire lamp unit has to be replaced. Even though the other components of the lamp unit except for the lamp, for example, the box case, have no damage, they are replaced and discarded together with the lamp. This wastes the components as well as increases the cost. Discarding the serviceable components results in waste of resources.

The present invention has an object to provide a projection display with a replaceable lamp involving the replacement of a minimum number of components.

In a projection display according to the present invention, a light modulating device modulates light from a light source according to an image signal and a projection lens enlarges and projects the light as an image. The projection display comprises a light source lamp section and a body. The light source lamp section includes a high-pressure discharge lamp, a metal reflector to which the high-pressure discharge lamp is attached and a plurality of engaging portions provided on a rim at an opening of the reflector. The body includes a lamp housing section having a hole and a plurality of engaged portions provided with the hole and for engaging with the engaging portions. The plurality of engaging portions on the rim of the reflector are engaged with the engaged portions of the lamp housing section to secure the light source lamp section to the body of the projection display.

According to the projection display, the light source lamp section having the reflector can be directly secured to the body, thereby reducing the number of components and resulting in cost reduction.

The engaging portions can be flanges formed on the outer region of the rim of the opening so as to project outwardly.

The engaging portions can be slots and slits adjoining the slots, both formed on the rim of the opening.

In addition, the reflector may include an explosion-proof glass secured at the front opening of the reflector by a screw. The high-pressure discharge lamp may be secured to the reflector by a screw.

In addition, the lamp housing section of the body may be provided with an explosion-proof glass.

Furthermore, the reflector may have cooling fins on the outer region in proximity of the focal point.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, embodiments of the present invention will be now described in detail. Through the drawings, the same or equivalent components are denoted by the same numerals and will not be further explained to avoid repetition.

FIG. 1is a perspective view of a light source lamp section of a projection display according to the first embodiment of the present invention.FIG. 2is a partially cut-out perspective view of the projection display body, in schematic form, to which a lamp unit is attached.FIG. 3is a schematic diagram of the light source lamp section of the projection display according to the first embodiment of the present invention.FIG. 4is a schematic diagram of the light source lamp section of the projection display, viewed from the rear, according to the first embodiment of the present invention.

As shown inFIG. 3, the light source lamp section1of the projection display according to the embodiment includes a high-pressure discharge lamp2, a metal reflector3to which this high-pressure discharge lamp2is secured and an explosion-proof front glass4for blocking the front opening of the metal reflector3.

The high-pressure discharge lamp2is, for example, a high pressure mercury lamp and has a light emitting portion21with a light emitting material filled therein. The metal reflector3has a concave reflecting surface in the shape of an ellipsoid, hemisphere or parabola. At the center of an optical axis of the concave reflecting surface, the high-pressure discharge lamp2is secured. InFIG. 3, lead wires and so on are omitted.

The light source lamp section1is detachable from the body70of the projection display as shown inFIG. 2. Such a detachable light source lamp section1is realized by placing a plug76, which corresponds to a pin75provided on the light source lamp section1, in the body70. There is no problem to place the pin75in the body70and the plug76on the light source lamp section1.

When the light source lamp section1is attached into the body70, the pin75is coupled with the plug76. The plug76is electrically connected with a lighting circuit (not shown) in the body70. The lighting circuit starts/lights the high-pressure discharge lamp2of the light source lamp section1. A cooling fan77is mounted behind the light source lamp section1set in the body70and a cover71is attached above the light source lamp section1.

Inside the body70, there are an optical system having a lamp as a light source and an image modulating means that is used to control the optical system to display images and includes a liquid crystal panel and so on. Light emitted from the high-pressure discharge lamp2passes the optical system and a projection lens74and is projected on a screen as an image.

Some of projection displays capable of producing images in color employ three primary colors, red (R), green (G), blue (B).FIG. 5is a schematic diagram of a three-liquid-crystal-panel (3LCD) projection display using a dichroic prism system as a projection display.

The 3LCD projection display with the dichroic prism system will be now described by referring toFIG. 5. The light source lamp section1of the 3LCD projection display100includes a high-pressure discharge lamp2and a parabolic reflector3that converts white light emitted from the high-pressure discharge lamp2into an approximately collimated light beam. Then, the light emitted from the light source lamp section1passes a UVIR filter (not shown) to remove its UVIR components for the purpose of reducing heat load on the following optical members.

The collimated light emitted from the parabolic reflector3is split into light beams by a fly-eye integrator consisting of first and second fly-eye lenses103,104both including a group of convex lenses. Each light beam is converged and incident to a polarizing converter105that aligns the polarizing directions of the light beams and emits them. After the light beams having a single polarization pass a condenser lens106, light in the red to green wavelength passes a dichroic mirror107, while light in the blue wavelength is reflected off the dichroic mirror107.

The light in the blue wavelength, which is reflected by the dichroic mirror107and changes its optical path at 90 degrees, is further reflected off a total reflection mirror108and changes its optical path at 90 degrees. Then, the light enters through a field lens109B to a blue liquid-crystal display element120B for displaying images having light components in the blue wavelength, in which the light is modulated according to input signals. The modulated light enters a dichroic prism121that bends the optical path of the light at 90 degrees and then enters a projection lens74that projects the light as an enlarged image on a screen (not shown).

On the other hand, the light in the red to green wavelength, which passed the dichroic mirror107, enters a dichroic mirror112. Since the dichroic mirror112has a property of reflecting light in the green wavelength, light in the green wavelength is reflected by the dichroic mirror112and changes its optical path at 90 degrees. Then the light enters through a field lens119G to a green liquid-crystal display element120G for displaying images having light components in the green wavelength, in which the light is modulated according to input signals. The modulated light in the green wavelength enters a dichroic prism121and projection lens74in sequence and is projected as an enlarged image on the screen.

The light in the red wavelength, which passed the dichroic mirror112, passes lenses123,124, total reflection mirrors126,127and a field lens129R and enters a red liquid-crystal display element120R for displaying images having light components in the red wavelength, in which the light is modulated according to input signals. The modulated light in the red wavelength enters a dichroic prism121that bends its optical path at 90 degrees and enters the projection lens74that projects the light as an enlarged image on the screen. Each of the liquid-crystal display elements120B,120G,120R includes a polarizer for input PI, a liquid crystal LC and a polarizer for output PO.

The reflector3of the light source lamp section1according to the embodiment is made of metal and has a plurality of flanges32, which are engaging portions, provided on a rim31at an opening of the reflector3so as to project outwardly. In this embodiment, three flanges32are arranged at intervals of 120 degrees. Since the reflector3is made of metal, the flange32can be added easily by bending work and so on.

As shown inFIG. 2, in this embodiment, an attachment section5, which is positioned where the light source lamp section1is attached and housed (lamp housing section), of the body70has a hole51to which the outer region of the rim31of the reflector3is inserted. This hole51is provided with slots52to which the flanges32are inserted and claws53adjoining the slots52at intervals of 120 degrees.

As shown inFIGS. 2 and 4, the flanges32of the reflector3are aligned with the hole51of the attachment section5in the body70, and then the reflector3is turned in the direction of the arrow to engage the flanges32with the claws53. The engagement of the flanges32and claws53secures the light source lamp section1at a predetermined position of the hole51of the attachment section5in the body70.

This engagement of the slots52and claws53of the attachment section5in the body70and the flanges32formed on the rim31of the reflector3can be made in the same method of aligning and turning claws and slots often used to secure a ceiling light, for example.

According to the embodiment, the light source lamp section1having the reflector can be secured directly to the body of the projection display, thereby reducing the number of components and resulting in cost reduction.

Referring toFIGS. 6 to 11, a description will be made about the second embodiment of the present invention.FIG. 6is a schematic diagram of a light source lamp section of the projection display according to the second embodiment of the invention.FIGS. 7 and 8illustrate the part, to which the lamp is inserted, of the body of the projection display according to the second embodiment of the invention:FIG. 7is a front view; andFIG. 8is a cross-sectional view taken along the line A-A inFIG. 7.

As shown inFIG. 6, the reflector3of the second embodiment is provided with three slots35and three slits36adjoining the slots35, both constitute engaging portions, on a rim31of the reflector3along its circumference at intervals of 120 degrees. While the flanges32function as engaging portions in the first embodiment, the slots35and slits36function as the engaging portions in the second embodiment.

An explosion-proof front glass is attached in the inner region of the rim31, but is not illustrated.

There is a hole51at a part (lamp housing section) of the attachment section5in the body70so that the outer region of the rim31of the reflector3can be inserted. In order to engage the slots35and slits36of the reflector3, protrusions54are provided on the hole51at intervals of 120 degrees as shown inFIGS. 7 and 8. Each protrusion54has a width slightly smaller than the width of the slot35and slit36of the reflector3and a thickness slightly smaller than the depth of the slit36.

To insert and secure the light source lamp section1to the hole51of the attachment section5in the body70, the slots35of the lamp section1are aligned with the protrusions54of the hole51of the attachment section5as shown inFIG. 9. Then, as shown inFIG. 10, the protrusions54are inserted into the slots35of the reflector3. Subsequently, the lamp section1is turned in the direction of the arrow with the protrusions54abutting the back of the slots35until the slits36are engaged with the protrusions54as shown inFIG. 11. Thus, the light source lamp section1is secured at a predetermined position of the hole51of the attachment section5.

According to the second embodiment, the light source lamp section1having the reflector3can be directly secured to the body70of the projection display, thereby reducing the number of components and resulting in cost reduction.

FIG. 12is a cross-sectional view showing a part, to which the light source lamp section is attached, of the attachment section5in the body70according to the third embodiment of the present invention.

While the explosion-proof front glass4is attached to the reflector3of the lamp section1in the second embodiment, in the third embodiment, ribs55are provided at the front of the hole51of the attachment section5in the body70in order to hold an explosion-proof glass4. Since the explosion-proof glass4is attached on the body, the lamp section1does not need to have the explosion-proof glass. As a result, the unit price of a replacement lamp can be reduced.

FIG. 13is a schematic diagram of a light source lamp section of the projection display according to the fourth embodiment of the present invention. In the fourth embodiment, the explosion-proof front glass4and high-pressure discharge lamp2described in the first and second embodiments are secured to the reflector3by securing screws6. In the first and second embodiments, the explosion-proof front glass4and high-pressure discharge lamp2are fixed with an adhesive. The use of the screws6instead of the adhesive to secure the explosion-proof front glass4and high-pressure discharge lamp2in the fourth embodiment simplifies the manufacturing process. If the front glass or the high-pressure discharge lamp2is damaged, the reflector3can be detached by unscrewing the screws6and a new explosion-proof front glass or high-pressure discharge lamp2can be attached to the reflector3, thereby realizing reuse of the reflector3.

It is preferable to use special screws as the screws6so that general users cannot take out the screws. That is because the general users may be able to replace the explosion-proof front glass and high-pressure discharge lamp, but may not be able to appropriately set them, and such a risk should be avoided as much as possible.

Furthermore, the reflector3in the fourth embodiment has integrally-formed radiating fins7on the outer region that is close to the focal point and therefore is raised to the hottest temperature. The provision of the radiating fins7on the hottest region of the reflector3improves heat dissipation of the lamp section1, and therefore increases the life of the lamp.

The present invention is used in an optical engine of a projection display such as a projector and a rear projector.

It should be understood that the embodiments disclosed herein are to be taken as examples in every point and are not limited. The scope of the present invention is defined not by the above described embodiments but by the appended claims. All changes that fall within means and bounds of the claims, or equivalence of such means and bounds are intended to be embraced by the claims.