Optics: image projectors – Composite projected image – Multicolor picture
Reexamination Certificate
1999-06-10
2002-06-25
Adams, Russell (Department: 2851)
Optics: image projectors
Composite projected image
Multicolor picture
C361S816000
Reexamination Certificate
active
06409347
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a circuit board accommodated in a casing together with a driving system of an electronic apparatus and to electrically control said driving system, to an electronic apparatus using the circuit board, and to a projection display device serving as such an electronic apparatus.
2. Description of the Related Art
Hitherto, an electronic apparatus has been used which includes a driving system, a circuit board for electrically controlling the driving system, and a casing for accommodating therein the driving system and the circuit board. As such an electronic apparatus, for example, a projection display device has been known which includes an optical system for optically processing a luminous flux emitted from a light source so as to form an optical image according to image information, a driving system including a projection lens for enlarging. and projecting the optical image onto a projection plane, a circuit board for electrically controlling the optical system and the driving system, and a casing for accommodating therein the optical system, the driving system, and the circuit board. In such a projection display device, the circuit board is often disposed above the optical system in parallel with a plane that is defined by an optical axis of the optical system.
The projection display device is widely used in multimedia presentations at conferences, academic meetings, exhibitions, etc., and hence it is necessary to improve portability in order to facilitate transportation of the device to meeting places, and a further reduction in size is demanded.
In order to meet such a demand, however, it is necessary to achieve a reduction in size of components of the optical system and to achieve a reduction in thickness of the circuit board disposed above the optical system. In particular, since the reduction in thickness of the circuit board is limited, the overall device cannot be sufficiently reduced in thickness, and a reduction in size of the device is prevented.
In addition, devices, such as a videocassette recorder and a computer, are connected to such a projection display device, and image information output therefrom is modulated by an optical modulation device constituting the optical system. This allows the projection display device to form an optical image according to the image information. More specifically, a composite signal and an RGB signal serving as image information are supplied to the optical modulation device via an optical-modulation-device driving system for driving and controlling the optical modulation device. The optical-modulation-device driving system converts, by a predetermined signal processing, image signals, such as the composite signal and the RGB signal, into signal forms suitable for image display and supplies the converted signals to a portion for driving the optical modulation device. Such an optical-modulation-device driving has been integrally formed on one circuit board as a circuit for driving the optical modulation device by input image signals.
However, the above conventional optical-modulation-device driving system formed on one circuit board encounters the following problems. That is, the optical-modulation-device driving system includes a portion that is set up according to specifications of the optical modulation device, such as the resolution (such as VGA or SVGA resolution) of the optical modulation device, and a portion that does not depend on the specifications of the optical modulation device, such as a portion for processing the composite signal and the RGB signal so as to be suitable for image display. According to the conventional optical-modulation-device driving system formed on one circuit board, a circuit board including a signal processing portion that does not depend on the specifications of the optical modulation device should be set up specifically according to the specifications of the optical modulation device of the projection display device. This is inefficient from a manufacturing viewpoint.
In addition, formation of the optical-modulation-device driving system on one circuit board increases the size of the circuit board, and this is undesirable for achieving a reduction in size of the projection display device.
Furthermore, in order to ensure a stable operation of the circuit board by preventing noise radiation, a ground section is provided on the inner peripheral surface of the casing of the projection display device, and the ground section and the circuit board are electrically connected.
More specifically, according to the conventional projection display device, the circuit board disposed horizontally above the optical system is fixed to the inner peripheral surface of the casing by a plurality of fixing screws. The fixing screws are electrically connected to the ground section, and noise generated on the circuit board is radiated at the ground section via the fixing screws to thereby achieve a stable operation of the circuit board.
However, since there is a tendency to reduce the weight, size and thickness of the overall electronic apparatus like the above conventional projection display device as described above, grounding of the circuit board by the fixing screws will restrict fixing points of the circuit board. Therefore, the electrical connection between the circuit board and the ground section via the fixing screws cannot be sufficiently effected. In addition to the electrical connection by the fixing screws, the electrical connection between the circuit board and the ground section may be achieved by providing a special connecting line on the circuit board, but this complicates the structure of the circuit board and is not desirable from the viewpoint of reducing the size of the device.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a projection display device capable of reliably reducing the thickness and size thereof without being affected by the thickness of a circuit board.
A projection display device of the present invention is intended to achieve the above object by changing a layout of a circuit board. More specifically, according to an aspect of the present invention, there is provided a projection display device including an optical system for optically processing a luminous flux emitted from a light source so as to form an optical image according to image. information; a projection lens for enlarging and projecting an image formed by the optical system onto a projection plane; a circuit board for controlling the device; and a casing for substantially covering the optical system, the projection lens, and the circuit board in entirety, characterized in that the circuit board is substantially perpendicular to a plane defined by optical axes of the optical system, and is disposed longitudinally on an outside of the plane defined in the optical system.
In the projection display device of the present invention, when the plane defined by the optical axes of the optical system is set horizontally, for example, the circuit board is allowed to stand aside the optical system. Therefore, by designing the circuit board so as to have a small size, the entire thickness of the projection display device can be reduced because the circuit board is not disposed above the optical system. Therefore, unlike the conventional projection display device in which a circuit board is disposed above an optical system, the thickness of the entire device can be reliably reduced regardless of the thickness of the circuit board, whereby a reduction in size of the device is sufficiently facilitated.
In addition, in the projection display device of the present invention, the circuit board may be disposed in such a manner that one surface of the circuit board closely oppose an inner surface of the casing, and a guard member may be provided between the circuit board and the casing so as to prevent interference therebetween.
That is, the guard member is provided between the circuit board and the casing, so that interferenc
Furuhata Mutsuya
Koyama Fumio
Kuroda Akitoshi
Nakazawa Toshihiko
Takizawa Takeshi
Fuller Rodney
Oliff & Berridg,e PLC
Seiko Epson Corporation
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