Optics: image projectors – Lens support – Lens position adjustable
Reexamination Certificate
2001-05-09
2003-07-15
Adams, Russell (Department: 2851)
Optics: image projectors
Lens support
Lens position adjustable
C353S069000, C353S070000, C352S140000, C348S745000
Reexamination Certificate
active
06592228
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a projector that projects an image formed on an image display device, such as a liquid crystal panel, via a projection lens, and particularly relates to a technique of simplifying adjustments made to projection conditions of the projector.
BACKGROUND ART
In recent years, so-called “light-valve type” projectors have come into widespread use. A light-valve type projector forms an image on a light valve, such as a liquid crystal panel, and projects the image onto a screen via a projection lens.
When such a conventional projector is set in a space, such as a hall, the procedure shown as the flowchart in
FIG. 1
has been employed.
As shown in
FIG. 1
, the setting procedure for a projector
200
(see
FIG. 2
) is roughly divided into two stages. One stage is for the preliminary setting of the projector
200
(steps S
501
to S
504
), and this stage is referred to as the “simulation”. The other stage is for the actual setting of the projector
200
at the site (steps S
505
to S
510
), and setup and adjustments of the projector
200
are performed in this stage.
In the simulation, a size of an image to be projected by the projector
200
(this size is referred to as the “projection display size” hereinafter) is first set (step S
501
). Then, a distance between a projection lens
210
of the projector
200
and a screen
300
(this distance is referred to as the “projection distance” hereinafter) and a vertical positional relation between the projector
200
and the screen
300
are roughly set (step S
502
).
FIG.
2
and
FIG. 3
are respectively a side view and a top plan view showing the positional relation between the projector
200
and the screen
300
. In
FIG. 2
, a distance L
1
indicates the projection distance measured between the screen
300
and the projection lens
210
of the projector
200
. A distance L
2
indicates the vertical relative distance between the screen
300
and the projector
200
. The distance L
2
is calculated by subtracting a distance between the vertical center of the projection lens
210
and the floor from a distance between the vertical center of the screen
300
and the floor.
As to the projection distance L
1
and the vertical relative distance L
2
, a user refers to specifications of a plurality of projection lenses prepared for the projector
200
and roughly sets these distances with consideration given to various conditions, such as space, of the setting site.
Based on the results of the above rough settings, an appropriate lens is selected from the plurality of projection lenses prepared for the projector
200
(step S
503
). Selecting the optimum lens largely depends on the zoom ratio of the projection lens
210
and the availability of the zoom function.
When the projection lens having the zoom function is selected as the projection lens
210
, the zoom ratio is set and an amount of vertical axis displacement adjustment is roughly calculated.
Here, the amount of vertical axis displacement adjustment refers to an amount by which the position of the light valve is adjusted relative to the optical axis of the projection lens
210
in the vertical direction. This adjustment is made so that a projection position of an image coincides with the correct position of the screen
300
in the vertical direction. The amount of vertical axis displacement is easily obtained from the zoom ratio and the vertical relative distance L
2
between the screen
300
and the projector
200
that was calculated in step S
502
.
When this amount of vertical axis displacement exceeds the maximum amount described in the specifications of the projector
200
, a support table
250
is set under the projector
200
to make up an insufficient height (step S
504
). Accordingly, the rough simulation based on the specifications of the projector
200
is completed.
Next, the setup and adjustments of the projector
200
performed in accordance with the stated rough simulation is explained.
First, based on the results of the simulation, the position of the projector
200
to be set at the site is determined (step S
505
). Here, the setting position of the projector
200
should be determined with a high degree of precision in accordance with the projection distance obtained in the simulation. Also, the setting direction of the projector
200
and the positional relation between the projector
200
and the screen
300
should be adjusted at a high degree of precision. To be more specific regarding the positional relation, the setting direction of the projector
200
should be adjusted so as to be parallel to the direction of the normal to the screen
300
in the horizontal direction, while it should be adjusted in the vertical direction so as to correspond to a predetermined setting angle as specified for the projector
200
.
After the projector
200
has been accordingly positioned, the projector
200
is turned on and an image actually projected onto the screen
300
is assessed. In general, the projection distance is rechecked by actual measurement in a case where the adjustment performance for the projected images is highly valued (step S
506
).
When the setting position of the projector
200
is judged to be imperfect from the assessment of the image projected on the screen
300
and actual measurement of the projection distance (“NG” in step S
506
), the processing returns to step S
505
to reset the position of the projector
200
. On the other hand, when the setting position of the projector
200
is judged to have no problems from the assessment of the image projected on the screen
300
and actual measurement of the projection distance (“OK” in step S
506
), the processing advances to step S
507
. When the projection lens
210
is a zoom-type lens, adjustment to the zoom ratio of the projection lens, the so-called “zoom adjustment”, is performed (step S
507
). Following this, adjustment to the vertical axis displacement of the projection lens
210
is performed (step S
508
). Then, the focus of the projection lens
210
is adjusted (step S
509
).
The zoom adjustment, vertical axis displacement adjustment, and focus adjustment are not completely independent of one another. Therefore, the user has to execute these adjustments as necessary while viewing the image projected on the screen
300
. More specifically, if the zoom ratio is changed, the amounts of axis displacement and focus adjustments will also vary and so have to be accordingly adjusted. While making fine adjustments, the user reassesses the image projected on the screen
300
. If the projection state resulting from the fine adjustments is judged to be inadequate, the zoom ratio, axis displacement, and focus adjustments are repeated so as to converge on an optimum projection state.
After these adjustments have been completed, it is confirmed that the projection display size, geometric distortion, and consistency in the focus performance for the entire display area satisfy a level required for the current use of the projector
200
(step S
510
). If there are still problems in the projection conditions of the projector
200
in this stage of confirming the adjustment results (“NG” in step S
510
), the processing returns to step S
505
to reset the position of the projector
200
. Then, the fine adjustments to the position of the projector
200
and readjustments to the projection lens system are repeated. When the image quality is judged to be adequate to the level required for the current use of the projector
200
(“OK” in step S
510
), the projector setting including the setup and adjustments is terminated.
For the conventional projector, the adjustments to the projection lens are electrically controlled in order to help simplify the adjustments to the projector.
FIG. 4
shows a construction example of a driving system that is provided for such a conventional projector to drive the projection lens.
As shown in
FIG. 4
, the driving system of the projection lens
210
is composed of a focus driving unit
211
, a zoom driving unit
212
, a vertical axis dis
Gyoten Takaaki
Kawashima Masahiro
Adams Russell
Koval Melissa J.
Matsushita Electric Industrial Co. LTD
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