Illumination – Light source and modifier – Including reflector
Reexamination Certificate
2000-11-27
2004-08-17
Cariaso, Alan (Department: 2875)
Illumination
Light source and modifier
Including reflector
C362S277000, C362S319000, C445S004000, C445S064000
Reexamination Certificate
active
06776510
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a light source apparatus including a light source and a concave mirror and a method for manufacturing the same, an adjusting device for adjusting the optical arrangement of the light source and the concave mirror so that light from the light source can be utilized in the light source apparatus with maximum efficiency, and a lighting system and a projection display system using the light source apparatus.
BACKGROUND ART
In recent years, projection display systems using various types of optical modulators have drawn attention as an imaging apparatus for projecting on a large screen. When displaying on a large screen with these projection display systems, a most significant characteristic is brightness. The brightness is determined depending on the luminance of a lamp, the condensing efficiency of a reflector, the lighting efficiency of a lighting lens system, the efficiency of utilizing the light of an optical modulator, and the like. Among these, to utilize the luminance of the lamp and the condensing efficiency of the reflector at a maximum, it is necessary to adjust the optical arrangement of the lamp and the reflector properly. If the optical arrangement is not adjusted, sufficient light output cannot be obtained.
In a projection display system, because the life of the lamp is shorter than the life of the entire system, most projection display systems are provided with a mechanism capable of exchanging a lamp housing assembly, for example, when the lamp is exhausted. This lamp housing assembly is a light source apparatus which is configured to be removable from the projection display system, and comprises a reflector and a lamp fixed after being adjusted for its position with respect to the reflector.
Traditionally, in an exchangeable lamp housing, for size reduction or cost reduction, the position of the lamp with respect to the reflector is determined by fixing a reflector anchoring plate for anchoring the reflector, to the bottom plate of the lamp housing, and adjusting only the position of the lamp. That is, the position of the reflector with respect to the bottom plate of the lamp housing is fixed. Furthermore, the position of the lamp is adjusted under the condition in which the lamp housing is incorporated in a projection display system, or under the condition in which the lamp housing is incorporated in an optical system of a partly simplified projection display system.
As the reflector, metal reflectors produced by electrolytic deposition, glass reflectors, and the like may be used. Although these reflectors are different in their respective materials, they are common in having machined end faces. In general, the dimensional tolerance of the external shape of the reflector is about from 0.1 mm to 0.5 mm.
As a first prior art example for adjusting a light source apparatus,
FIG. 18
shows a basic configuration of an adjusting means disclosed in the publication of JP-5-313117A. In this configuration, only the position of the lamp is adjusted.
In the conventional configuration shown in
FIG. 18
, the traveling direction of light reflected by a reflector
202
is determined as the direction of Z-axis, and the directions crossing at right angles in a plane crossing perpendicularly to the Z-axis are determined as the directions of X-axis and Y-axis, respectively. First, a lamp
201
is moved and positioned in the direction of Z-axis so that illumination of light irradiated on a screen
215
by reflected light is at a maximum, and so that the ratio of the amount of light at the center to the periphery on the screen
215
is at a minimum.
Then, the lamp
201
is moved in the direction of X-axis or Y-axis, and positioning is carried out by adjusting the position of the lamp
201
in the direction of X-axis or Y-axis so that the position of the greatest illumination of light irradiated on the screen
215
by reflected light becomes the center of the screen.
Next, as a second prior art example for adjusting a light source apparatus, a configuration disclosed in the publication of JP-9-138378A is shown. In this configuration, only the position of the reflector is adjusted. In this second prior art example, first, as shown in
FIG. 19
, a semiconductor laser
316
and a photodiode
317
are placed on an optical axis
110
at positions where the first and second focal points of an ellipsoidal reflector
315
should be located, respectively.
Then, the ellipsoidal reflector
315
is placed at an approximate position, and light emitted from the semiconductor laser
316
is reflected by the ellipsoidal reflector
315
and received by the photodiode
317
.
The procedure for adjustment is as follows: first, the ellipsoidal reflector
315
is moved in the direction of the optical axis
110
, and adjusted for its position so that the light spot at the photodiode
317
at a minimum. At this time, the light spot is not necessarily located on the optical axis
110
.
Then, the ellipsoidal reflector
315
is moved in the directions crossing perpendicularly to the optical axis
110
, and adjusted for its position so that the light spot at the photodiode
317
is at a minimum. At this time, the light spot also is not necessarily located on the optical axis
110
. Then, adjustment is carried out by changing the tilt of the ellipsoidal reflector
315
so that the position of the light spot at the photodiode
317
is on the optical axis
110
. In the second prior art example, the position of the ellipsoidal reflector
315
is adjusted by the above procedure.
As a third prior art example for adjusting a light source apparatus, a configuration disclosed in the publication of JP-10-97973A is shown. In this configuration, parts other than the lamp and the reflector are adjusted. In this third prior art example, as shown in
FIG. 20
, a discharge lamp
401
is arranged so that the portion of the largest luminance in its luminous part is located at the first focal point of an ellipsoidal condensing mirror
402
.
The second focal point of the ellipsoidal condensing mirror
402
is located in the outgoing part of the lamp housing, and light of the lamp is condensed on the second focal point. The outgoing part of the lamp housing is provided with an illumination adjusting mechanism
411
, which moves the position of the incoming end of light-transmitting fiber
412
in the direction of the optical axis
110
. Illumination is adjusted by adjusting the distance between the incoming end of the light-transmitting fiber
412
and the second focal point, with this illumination adjusting mechanism
411
.
In the first prior art example, because adjustment is carried out only for the lamp, but not for the reflector, there is a problem that when the dimensional tolerance of the reflector is large, light output is reduced. Table 1 shows an example of the relationship between the tolerance of the reflector (ellipsoidal mirror, spherical mirror) in the direction of the optical axis, and light output. As is known from this table, when there is a tolerance of 0.5 mm, light output is decreased by 14%.
TABLE 1
Tolerance in the direction
of the optical axis
(tolerance in the direction
Change in light
Change in light
of condensing light from
output when an
output when a
design position is
ellipsoidal mirror
spherical mirror
determined positive)
has a tolerance
has a tolerance
−0.5 mm
86%
95%
−0.4 mm
90%
98%
−0.3 mm
94%
100%
−0.2 mm
97%
100%
−0.1 mm
98%
100%
0 mm
100%
100%
+0.1 mm
96%
97%
+0.2 mm
94%
96%
+0.3 mm
93%
96%
+0.4 mm
91%
91%
+0.5 mm
86%
87%
Furthermore, in the first prior art example, because it is necessary to adjust the light source apparatus by detecting irradiated light projected on the screen
215
, adjustment can be carried out only under the condition in which the lamp
201
is lighted after assembling a display system including a lens
212
, an optical modulator
213
, and a projection lens
214
. Consequently, the work efficiency of the adjustm
Sannohe Shinya
Shimaoka Yuusaku
Yoshikawa Takamasa
Cariaso Alan
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P.C.
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