JP3565734B2 - Projection display device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projection display device that uses a parabolic mirror and a DC lighting lamp as light sources, uniformly illuminates a display element via a fly-eye lens and a relay lens, and projects image information of the display element on a screen.
[0002]
[Prior art]
FIG. 5 is a schematic diagram for explaining an example of a conventional general projection display device. The lamp 28 disposed near the focal point irradiates the fly-eye lens 22 with substantially parallel light by the reflection action of the parabolic reflector 21. Each of the frames of the fly-eye lens 22 has a shape similar to that of the display element 25, and the image of the frame of the fly-eye lens 22 is projected at a magnification β via the fly-eye lens 23 and the relay lens 24. Superimposed.
[0003]
The light beam emitted from the lamp 28 is split into a plurality of light beams by the fly-eye lens 22, converges at the position of the fly-eye lens 23, and forms a plurality of light source images.
Since the display element 25 is illuminated with a plurality of light source images, uniform illumination can be obtained.
The uniformly illuminated image of the display element is enlarged by a projection lens 26 and projected on a screen 27.
[0004]
In a fly-eye optical system, when the angle of a ray incident on the fly-eye is nearly parallel to the optical axis, the ray can be used effectively, and an effective angle range indicating a range in which the ray can be used effectively can be defined. it can. Therefore, when the angle exceeds a certain angle, that is, out of the effective angle range, the light beam becomes invalid.
Light rays from a point light source at a parabolic focal point become light rays parallel to the optical axis, but light rays emitted from other than the focal point do not become light rays parallel to the optical axis. This is because the actual light source has a finite size.
[0005]
[Problems to be solved by the invention]
Incidentally, there are a DC driving method and an AC driving method as a method for driving the lamp. Compared with the AC drive system, the DC drive system has a feature that the luminance distribution of the light source is smaller and the light source approaches the point light source and the screen becomes brighter.
The direct-current drive system has a characteristic that the luminance distribution is biased toward one side of the electrode with respect to the center, as shown in FIG. Therefore, as described above, although it is closer to a point light source as compared with the AC drive method, a lot of light rays that are reflected by the parabolic reflector and are not parallel to the optical axis are emitted and the light use efficiency is reduced. is there.
[0006]
An object of the present invention is to solve the above-described problem, and in a projection display device using a light source composed of a parabolic reflector and a lamp, the use efficiency of light emitted by a DC-driven lamp is further improved to improve a projection screen. It is an object of the present invention to provide a projection display device capable of emitting light with high brightness and high uniformity.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a projection display device according to the present invention includes a parabolic mirror and light emitted from a light source including a DC lighting lamp disposed at a focal point of the parabolic mirror, incident on a fly-eye lens. In a projection display device, a plurality of light source images are obtained, a display element is uniformly illuminated by passing through a relay lens system, and an enlarged image of image information of the display element is obtained on a screen by a projection lens.
A cathode side is arranged on the parabolic mirror opening side, and the DC lighting lamp is attached such that a peak position of a luminance distribution coincides with a focal position of the parabolic mirror,
In front of the parabolic mirror, arranged condenser lens having a positive refractive power, luminance distribution characteristics of the dc lighting lamp having a bias having a peak of luminance distribution on the cathode side in the parabolic mirror opening side Is corrected so that the number of rays falling within the effective angle range to the fly-eye lens increases.
[0008]
[Action]
According to the configuration, the utilization ratio of the light emitted from the lamp is improved, and the screen can be illuminated with higher luminance and higher uniformity as compared with the related art.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First, the luminance distribution of the DC drive method will be described.
FIG. 1 is a diagram showing a luminance distribution of a DC-driven lamp. Between the cathode and the anode, there is a high brightness peaking at a position close to the cathode side, and the brightness decreases sharply on the cathode side. On the other hand, the anode side has a characteristic of gradually decreasing.
[0010]
FIG. 2 shows an optical path when the DC-driven lamp is arranged at the focal position of the parabolic reflector.
The lamp is mounted so that the peak value of the luminance distribution coincides with the focal position of the parabolic reflector. The light emitted from the focal point F is reflected by the parabolic reflector and becomes parallel light. Light rays on the anode side having a large luminance distribution are reflected by the parabolic reflector to become divergent light, and the light rays in this portion cannot be used.
[0011]
FIG. 3 is a schematic diagram showing an embodiment of the projection display device according to the present invention.
5, the fly-eye lenses 3, 4, the relay lens 5, the transmissive display element 6, the projection lens 7 and the screen 8 correspond to the fly-eye lenses 22, 23, the relay lens 24, the display element 25, the projection lens 26 and It has the same configuration as the screen 27.
A condenser lens 2 having a positive refractive power is provided in front of the parabolic reflector 1 having a DC drive lamp 9 disposed at a focal position. By arranging the convex condenser lens 2 in this manner, the light rays emitted from the parabolic reflector 1 are converged weakly as a whole, thereby increasing the light use efficiency.
[0012]
FIG. 4 is a diagram showing a luminance distribution conversion into an effective angle range by a condenser lens.
The range within the dotted line position is the effective angle range, and when a light beam enters the fly-eye lens 3 at an angle in this range, it irradiates the screen. Outside this range, the angle becomes more convergent or divergent, and does not contribute to the illuminance of the screen.
FIG. 4A shows a conventional configuration in which a condenser lens is not inserted. The luminance is sharply reduced on the converging side, but the luminance is gently reduced on the diverging side, and the portion protruding from the dotted line is shown. The ratio is large.
[0013]
In the present invention, the light emitted from the focal point and reflected by the parabolic reflector 1 becomes parallel light, but bends to the converging side by the condenser lens 2. A condenser lens having a refracting power such that a part of the light beam slightly exceeds the dotted line range on the converging side is used.
On the other hand, light emitted from a position slightly shifted from the focal point of the light source is reflected in a direction diverging on the paraboloid, but is bent by the condenser lens 2 in a direction parallel to the optical axis.
FIG. 4B shows the characteristics when a condenser lens is inserted, and the characteristics are corrected so that the convergence side and the divergence side become substantially symmetric about the peak.
In this way, the degree of divergence of the light source is reduced, the parallel light is corrected to a weak convergent light, and the luminance distribution falling within the effective angle range is maximized. Thereby, the effective utilization rate of the light emitted from the DC driving lamp 9 can be improved.
[0014]
Next, a comparative example will be described with respect to the difference in the light collection rate between the device of the present invention and the conventional device.
The sum of the light rays emitted from the light source is A, and the sum of the light rays incident on a display element such as a liquid crystal is B, and the light collection rate C = B / A is defined.
The present invention has the same configuration as each optical member of each optical member of the conventional apparatus except that a condenser lens is inserted behind the parabolic mirror. Parabolic mirror used was a a = 50.8 ie opening diameter 50.8mm in formula y = 1 / (4a) × x 2. The focal length of the condenser lens is f = 300 mm. The arc length between the anode and the cathode of the light source is 2 mm, and the distance between the focal point of the parabolic mirror and the cathode is 0.2 mm. The luminance distribution is a DC lighting lamp biased to the cathode side, and the opening side of the parabolic mirror is the cathode.
As a result of the measurement as described above, a light collection rate of 18.4% can be obtained with the conventional apparatus (only the parabolic mirror), and 27.6% can be obtained with the apparatus of the present invention (parabolic mirror + condenser lens). Was. As a result, the light-collecting efficiency of the device of the present invention was improved by 27.6 / 18.4 = 1.5 times that of the conventional device.
[0015]
In the above embodiment, an example of a transmissive display element has been described. However, it is needless to say that the present invention can be applied to a reflective display element.
[0016]
【The invention's effect】
As described above, the present invention obtains a plurality of light source images by making light emitted from a light source composed of a parabolic mirror and a DC lighting lamp disposed at the focal point of the parabolic mirror incident on a fly-eye lens, In a projection display device that illuminates a display element uniformly by passing through a relay lens system and obtains an enlarged image of image information of the display element on a screen by a projection lens , a cathode side is arranged on a parabolic mirror opening side, and The DC lighting lamp is mounted so that the peak position of the luminance distribution coincides with the focal position of the parabolic mirror, and a condenser lens having a positive refractive power is arranged in front of the parabolic mirror, and the aperture of the parabolic mirror is set. It corrects the luminance distribution characteristic of the DC lighting lamp having a bias having a peak of luminance distribution on the cathode side on the side, so light is increased to enter the effective range of angles of the fly-eye lens That.
Therefore, as compared with the conventional case, the effective utilization of light is improved, and the effect of being able to irradiate the screen with higher brightness and higher uniformity with a DC driven lamp of the same output without increasing the diameter is obtained. is there.
[Brief description of the drawings]
FIG. 1 is a diagram showing a luminance distribution of a DC-driven lamp.
FIG. 2 is a diagram for explaining an optical path when a DC-driven lamp is arranged at a focal position of a parabolic reflector.
FIG. 3 is a schematic view showing an embodiment of a projection display device according to the present invention.
FIG. 4 is a diagram for explaining conversion of luminance distribution into an effective angle range by a condenser lens.
FIG. 5 is a schematic diagram for explaining an example of a conventional general projection display device.
[Explanation of symbols]
1, 21 ... parabolic reflector 2 ... condenser lenses 3, 4, 22, 23 ... fly-eye lenses 5, 24 ... relay lenses 6, 25 ... transmission display elements 7, 26 ... projection lenses 8, 27 ... screen 9 ... DC Drive lamp

Claims (1)

A plurality of light source images are obtained by inputting light emitted from a light source composed of a parabolic mirror and a DC lighting lamp disposed at the focal point of the parabolic mirror to a fly-eye lens, and displayed by passing through a relay lens system. In a projection display device that uniformly illuminates the element and obtains an enlarged image of image information of the display element on a screen by a projection lens,
A cathode side is arranged on the parabolic mirror opening side, and the DC lighting lamp is attached such that a peak position of a luminance distribution coincides with a focal position of the parabolic mirror,
In front of the parabolic mirror, arranged condenser lens having a positive refractive power, luminance distribution characteristics of the dc lighting lamp having a bias having a peak of luminance distribution on the cathode side in the parabolic mirror opening side Is corrected so that the number of rays falling within the effective angle range to the fly-eye lens increases.

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