GB2286743A - Image display device incorporating TV and video devices - Google Patents

Abstract

An image display device having a casing 11 enclosing a television device and a video player/recorder device. The display device includes a first printed circuit board area 14A which is provided with the electronic parts of a power supply circuit for the television and video devices and a second printed circuit board area 14B which is provided with the other electronic parts for the TV and video devices. <IMAGE>

Description

IMAGE DISPLAY DEVICE INCORPORATING TV AND VIDEO DEVICES This invention relates to an image display device having a casing enclosing a television device and a video device.

Figs. 1 and 2 illustrate a prior art image display device having a casing enclosing a television device and a video device. The video device 1 is placed on a bottom plate 2a of the casing 2, as shown in Fig. 2, and is secured at the front portion thereof to a front plate 2b of the casing 2 and at the rear portion thereof to a rear cabinet by means of screws 3.

The video device 1 includes a chassis la secured to a casing lb of a molded plastics material. As shown in Fig. 2, a plurality of printed circuit boards 4 for the video device 1 are arranged at the rear of the chassis la or casing lb.

A printed circuit board 5 for the TV device is disposed along one of the inner side surfaces of the casing 2. The circuit board 5 carries a power supply circuit for the TV device, including a high frequency transformer 6 for a high voltage circuit. A power supply circuit (not shown) for the video device is provided separately, on one of the printed circuit boards 4.

In Fig. 1 a shield plate 7 is shown disposed above the video device 1.

As described above, the construction of the prior art image display device is such that the video device is inserted into the casing of the TV device and secured in position. This type of construction requires large numbers of long wiring paths for connecting the printed circuit boards for the TV and video circuits. Furthermore, installation of the printed circuit boards for the TV and video circuits is both time and labour intensive.

In addition, because the power supply circuits for the TV and video circuits are provided separately , it is necessary to install a large number of parts. A further disadvantage is that noise generated by the power supply circuit for the TV circuit can be transmitted to the video device.

According to the present invention there is provided an image display device comprising: a casing; a television device; a video device including a video mechanism, said television and video devices being enclosed in said casing; a chassis, said video mechanism being installed on said chassis; a first printed circuit board area provided with electronic parts of an electron beam controlling circuit for a CRT and electronic parts of a power supply circuit for supplying power to said television and video devices; and a second printed circuit board area provided with electronic parts of said television and video devices with the exception of the electronic parts installed on said first printed circuit board area, said first and second printed circuit board areas being installed above the base of said casing and below the level of said chassis.

Preferably the power supply circuit includes a high frequency transformer installed in said first printed circuit board area, said transformer being provided with a core having first and second windings and a core gap, said transformer being positioned so that the plane of said core gap is substantially perpendicular to the flux direction that would cause most pick-up problems for the head gap of a video head cylinder of the video mechanism. In the illustrated embodiment the plane of the core gap is parallel to the surface of said first and second printed circuit board areas.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a cross-sectional view of a prior art image display device enclosing both TV and video devices in a common casing; Fig. 2 is a sectional plan view of the prior art image display device of Fig. 1; Fig. 3 is a rear cross-sectional view of an embodiment of image display device in accordance with the present invention; Fig. 4 is a cross-sectional side view of the image display device of Fig. 3; Fig. 5 is a longitudinal section through a high frequency transformer for use with the image display device of Fig. 3; and Fig. 6 is a side elevation of the high frequency transformer of Fig. 5.

In Figs. 3 and 4 there is illustrated an embodiment of image display device in accordance with the present invention, the device including a casing 11, a window 12 for a CRT and a port 13 for a speaker, both the window 12 and port 13 being provided in a front panel of the casing. A main circuit board 14 includes a power supply area 14A and an area 14B for the installation of various electronic parts. Guides 141, 142 are provided for the main circuit board.

A chassis 15, for installing various parts of the video mechanism, is supported by chassis guides 151, 152 which are formed integrally with a front panel 11b of the casing 11 and disposed in a plane parallel to the upper surface of a bottom plate gila.

Preferably, the chassis guide 151 is, as shown, provided with a tapered opening 151a at its proximal end and a support portion at its distal end. A similar opening 152a and similar support portion 152b are also formed at the proximal and distal ends respectively of the guide 152. The guides 141 and 142 for the main circuit board are also provided with openings 141a, 142a and support portions 141b, 142b, respectively.

Upper guides 151d and 152d for supporting the central portion of the chassis 15 are formed at the central portions of the chassis guides 151 and 152, respectively, and are arranged parallel to the upper surface of the bottom plate lla.

A high frequency transformer 16, a port 17 for a video cassette tape, and a shield plate 18 are also provided.

Parts of the video mechanism, such as a video head cylinder and the like, are mounted on chassis 15.

The parts for constituting the power supply circuit are installed in area 14A of the main circuit board 14, which area 14A is located on the lefthand side when viewing from the rear of the casing and occupies approximately one quarter of the total area of the board. The remaining area 14B occupies the remaining three quarters of the area of the board 14 and is used for the installation of the electronic parts except for the electron beam control circuit for the CRT of the TV device and for the electronic parts for the power supply circuits.

The video circuit and the TV circuit are preferably connected together by a printed circuit or the like, via the shortest path.

The terminals for the commercial-AC power supply and the terminals for the electron beam controlling circuit for the CRT are provided, separately of each other, in area 14A of the circuit board 14. Also provided in this area are a high voltage power supply, including a high frequency transformer, and a low voltage power supply for the TV and video devices.

Preferably, a common single low voltage power supply is used for both the TV and video circuits, resulting in a decrease in the number of the parts to be used. The low voltage power supply is connected to the TV and video circuits through the shortest path, using a printed circuit.

Figs. 5 and 6 show a high frequency transformer 20 having primary and secondary windings 30 and a core 31 with a core gap 32. The transformer 20 is preferahly fitted with the plane of the gap 32 parallel to the surface of the main circuit board 14. When arranged in this way the lines of magnetic flux or force run in a direction substantially perpendicular to the flux direction that causes most pick up problems for the head gap of the video head cylinder. This helps to reduce the noise generated by the high frequency transformer to a minimum level to eliminate the requirement for a magnetic shield around the high frequency transformer.

Claims (3)

1. An image display device comprising: a casing; a television device; a video device including a video mechanism, said television and video devices being enclosed in said casing; a chassis, said video mechanism being installed on said chassis; a first printed circuit board area provided with electronic parts of an electron beam controlling circuit for a CRT and electronic parts of a power supply circuit for supplying power to said television and video devices; and a second printed circuit board area provided with electronic parts of said television and video devices with the exception of the electronic parts installed on said first printed circuit board area, said first and second printed circuit board areas being installed above the base of said casing and below the level of said chassis.

2. A device as claimed in claim 1, wherein said power supply circuit includes a high frequency transformer installed in said first printed circuit board area, said transformer being provided with a core having first and second windings and a core gap, said transformer being positioned so that the plane of said core gap is substantially perpendicular to the flux direction that would cause most pick-up problems for the head gap of a video head cylinder of the video mechanism.

3. A device as claimed in claim 2, wherein the plane of said core gap is parallel to the surface of said first and second printed circuit board areas.