GB2153620A

GB2153620A - Liquid crystal television

Info

Publication number: GB2153620A
Application number: GB08432303A
Authority: GB
Inventors: Masaru Yoshida; Mitsuhior Murata
Original assignee: Citizen Watch Co Ltd
Current assignee: Citizen Watch Co Ltd
Priority date: 1983-12-20
Filing date: 1984-12-20
Publication date: 1985-08-21
Also published as: GB8432303D0

Abstract

Disclosed is a palm-sized liquid crystal television using a mirror 11 for presenting a reflection of an image appearing in a light transparent type liquid crystal display 14, thus assuring the presentation of light clear images to the eye without increasing the size of the whole apparatus. <IMAGE>

Description

SPECIFICATION Liquid crystal television Background of the invention Field of the invention The present invention relates to a liquid crystal television using a liquid crystal display.

Recently the rapid development in the field of electronics has been expediting the reduction of the size of electronic apparatus until palm-sized televisions appear in the market (for example, see Japanese Patent Application No. 136027/82).

In such a palm-sized television, a liquid crystal display is used because it requests a relatively small amount of electronic power. The liquid crystal displays commonly used are of the reflex type, disadvantageously presenting dark and hardly visible images on their screens.

Figure 1 shows a perspective view of a conventional liquid crystal television set, whose housing 2 is equipped with a reflex type liquid crystal display 1. Figure 2 shows diagrammatically a reflex type liquid crystal display 1 in section. As shown, the device is composed of an upper polarizing plate 5, an upper cell substrate 3, a liquid crystal layer (not shown), a lower cell substrate 4, a lower polarizing plate 6 and a reflex plate 7 in the order named. As seen from Figure 2, a ray of light 8 passes through the sandwich structure between the upper and lower polarizing plates 5 and 6 two times before reaching the eye, accordingly reducing the intensity of light and hence darkening the image appearing in the display.Another ray of light 8' reflects directly from the upper polarizing plate 5 or from the upper cell substrate 3 to reach the eye, thereby deteriorating the grade of contrast in the image appearing in the display, and accordingly making the image less clear.

One object of the present invention is to provide a liquid crystal television which is capable of presenting clear light images in its liquid crystal display without increasing the size of the whole apparatus.

Other objects and advantages of the present invention will be better understood from the following description of the preferred embodiments.

According to one aspect of the invention a liquid crystal television includes a light transparent liquid crystal display unit, a reflective surface for presenting a reflection of an image transmitted from the liquid crystal display unit and means for adjusting the relative angular positions of the liquid crystal display unit and the reflective surface so as to concentrate the reflected image.

According to second aspect of the invention, a liquid crystal television includes a first body block including a reflective surface on its upper portion and at least a tuner unit for receiving a television signal, a second body block including a light diffusing plate, a light-transparent type liquid crystal display associated with the second body block and at least one circuit for driving the liquid crystal display; connector means for establishing electrical connection between the electrical circuits contained in the first and the second body blocks thereby permitting rays of light to pass to the liquid crystal display via the light diffusing plate, and permitting the reflecting surface to reflect an image appearing in the liquid crystal display, thus presenting a reflection of the image to the eye.

Brief description of the drawings Figure 1 is a perspective view of a conventional palm-sized liquid crystal television Figure 2 is a diagrammatic section of a conventional liquid crystal display used in the liquid crystal television of Figure 1.

Figure 3 is a perspective view of a palm-sized liquid crystal television according to the present invention.

Figure 4 is a diagrammatic section of the liquid crystal display of the palm-sized television of Figure 3.

Figure 5 is a cross-section of the liquid crystal television according to the present invention, diagrammatically showing major parts of the apparatus.

Figure 6 is a block diagram of the circuit of a liquid crystal television according to one embodiment of the present invention.

Figure 7 is a block diagram of the circuit of a liquid crystal television according to another embodiment of the present invention.

Detailed description of preferred embodiments Figures 3 to 6 show a palm-sized liquid crystal television according to one embodiment of the present invention. Specifically Figure 3 is a perspective view of the liquid crystal television whereas Figure 4 is a diagrammatic section of a liquid crystal display used in the television of Figure 3.

As shown, the liquid crystal television comprises a first block or main body block 12 which contains a television receiver circuit including a tuning unit and other associated circuits (later described), and a power supply battery; and a second block or a hinged lid block 15 which contains a light diffusing plate 13 made of a ground glass and a light-transparent type liquid crystal display 14. An extendable antenna 35 and a speaker 36 are provided in the main body block 12.

The liquid crystal display 14 is composed of an upper polarizing plate 18, an upper cell substrate 16, a liquid crystal layer (not shown), a lower cell substrate 17 and a lower polarizing plate 19 in the order named. The hinged lid block 15 when not used, is folded flat on the main body block 12, thereby protecting a reflecting surface, for example a mirror 11 from being broken, and at the same time, facilitating the carry of the apparatus. In use, the hinged lid 12 is inclined and set at 45 degrees with respect to the main body block 12, as shown in Figures 3 and 4. Then, rays of light pass through the light diffusing plate 13 and the liquid crystal display 14 to fall on the mirror 11 to reflect therefrom and reach the eye, as shown in Figure 4. An observer can watch in the mirror 11 the reflection of an image appearing in the liquid crystal display 14.

With this arrangement rays of light pass through each component of the liquid crystal display 14 only one time to fall on the mirror 11 and reflect therefrom before reaching the eye. Therefore, a bright image results. Also, advantageously, some members for holding the liquid crystal display 14 and the light diffusing plate 13 are effective to prevent undesired rays of light such as indicated by broken lines in Figure 2 from reaching the eye, thus preventing the deterioration of contrast and assuring the appearance of clear images.

Figure 5 is a diagrammatical section of the liquid crystal television, showing essential components thereof. The apparatus is shown with its hinged lid 15 closed. The arrangement of different components in the main body block 12 has no direct connection to the idea of the present invention, and therefore no details are given in Figure 5. A television receiver circuit containing a tuning unit and other associated circuits is indicated at 20, and a circuit board constituting a part of the television receiver circuit is indicated at 30 in the drawing.

In the hinged hollow lid 15 the light diffusing plate 13 and the liquid crystal display 14 are held between an upper frame 21 and a lower frame 22, and there are airtight packings 23 between the upper and lower frames 21 and 22. Thus, the light diffusing plate 13 and the liquid crystal display 14 are put in an air-tight condition with the aid of the packings 23 when the hinged lid is closed.

The upper and lower frames 21 and 22 are made of a light-transparent plastic material such as acryl.

Metal plates each having a window opening 24a or 25a in conformity with the screen of the liquid crystal display 14, are applied to the upper and lower frames 21 and 22. With this arrangement rays of light pass through the window opening 24a of the upper frame 21, the light diffusing plate 13, the liquid crystal display 14 and the window opening 25a of the lower frame 22 before falling on the mirror 11. The material plates 24 and 25 surrounding the window openings of the upper and lower frames 21 and 22 are effective to increase the strength of the upper and lower frames 21 and 22, and at the same time, these windowed-metal plates define the area of screen for the liquid crystal display. Also, these metal plates 24 and 25 are held at the same potential as the power supply battery, thereby functioning as an electric field shield for the hinged lid 15.

Specifically, the drive signal for the liquid crystal display 14 is high both in frequency and voltage, and therefore if the electric field caused by applying the drive signal to the liquid crystal display 14 should leak outside from the hinged lid 15, the television receiver circuit in the main body block 20 and electronic apparatus around the television therearound if any, will be subjected to adverse effect. The use of metal plates is effective to suppress the leakage of electric field from the liquid crystal display to a possible minimum in spite of making the upper and lower frames of a transparent plastic.

One or more IC chips 26 are fixed to the under surface of the extension from the upper cell substrate 16 of the liquid crystal display 14, and a ter minal electrode (not shown) is provided to the under surface of the outer edge of the upper cell substrate 16. A connector 27 made of a flexible circuit board (FPC) is provided for the purpose of making an electrical connection between selected circuit of the main body block 12 and an associated circuit of the hinged block 15. As shown, one terminal part of the connector 27 is pushed against the terminal electrode of the upper cell substrate 16 under the resilient influence of rubber or other resilient body 28.

The connector 27 is covered with a shielding material and the connector 27 passes through the packing 23 to appear out of the hinged lid block 15.

The other terminal part of the connector 27 is pushed against the terminal electrode which is provided to the upper surface of the outer edge of the circuit substrate 30. In the main body block 12 the casing 31 holds the mirror 11, and the bottom plate 32 is applied to the open bottom of the casing 31. The lid block 15 is hinged to the main body block 12 as indicated at 33, thereby wallowing the lid block 15 to rise and incline at least at 45 degrees with respect to the main body block 12. Power supply batteries 34 are contained in the main body block 12.

Figure 6 shows a wiring block diagram of the liquid crystal television. In the drawing the main circuit block 20 is shown as comprising a television signal receiving circuit section including a tuning unit 40, a medium-frequency amplifier circuit 45 and a video-detecting-and-amplifier circuit 46; and an audio-circuit section 47 including an audio medium-frequency amplifier circuit 48, an amplitude limiting circuit 49, an audio-detector circuit 50 and an audio-amplifier circuit 51. As shown, the tuning unit 40 is composed of a high-frequency amplifier circuit 41, a mixer 42, a local oscillator circuit 43 and a channel selector circuit 44. The operations of these circuits are well known. Partly because of this and partly because of no connection to the idea of the present invention, such a description is omitted.

The hinged lid block 15 contains a synchronizing signal separator 61, an analogue-to-digital convertor 62 both connected to the television signal receiving circuit of the main circuit block, a control signal generator 63 connected to the synchronizing signal separator 61, a serial-to-parallel convertor 64 connected both to the analogue-to-digital convertor 62 and to the control signal generator 63, a line memory 65 connected both to the serial-to-parallel convertor 67 and to the control signal generator 63, a sweep driver circuit 66 connected to the control signal generator 63, a liquid crystal display driver circuit 67 connected both to the line memory 65 and the control signal generator 63. These circuits are made in the form of IC chips 26 as referred to above.

The television signal receiving circuit section which includes the tuning unit 40, the medium-frequency amplifier circuit 45 and the video signal detecting-and-amplifying circuit 46, sends a composite signal of video signal plus synchronizing signal both to the synchronizing signal separating circuit 61 and to the analogue-to-digital convertor 62. The synchronzing signal separating circuit 61 is responsive to the composite signal for separating the synchronizing signal, and the control signal generator 63 is responsive to the synchronizing signal for generating controller timing signals. The analogue-to-digital convertor 62 is responsive to the video signal for providing corresponding digital signal. The serial-to-parallel convertor 64 performs the serial-to-parallel conversion of digital signals under the control of the timing signals from the control signal generator 63.

The line memory 65 stores the signals from the serial-to-parallel convertor 64 under the control of the timing signals from the control signal generator 63.

The sweep drive circuit 66 provides sweep drive signals to the liquid crystal display 14 according to the timing signals from the control signal generator 63. Likewise, the liquid crystal display drive circuit 67 provides drive signals to the liquid crystal display 14 under the control of the timing signals from the control signal generator 63. All of these circuits are made in the form of IC chips 26.

In Figure 6, a power supply battery, a voltage regulator for changing the battery voltage to different voltages appropriate for applying to circuit components, and connections from the voltage regulator to such circuit components are omitted for the sake of simplicity in the drawing.

The connector 27 is composed of signal supplying conductor connecting the video detector-andamplifier circuit 46 to the synchronizing signal separator 61 and the analogue-to-digital convertor 62 for directing the composite signal to the latter circuits 61 and 62; and power supply conductors connecting the voltage regulator provided in the main body block 12 to circuit components in the hinged lid 15 for supplying electric power to such circuit components.

Figure 7 shows a circuit diagram of a palm-sized liquid crystal television according to another embodiment of the present invention. The same components as shown in Figure 6 are indicated by the same reference numerals as used in Figure 6.

As seen from Figure 7, a synchronizing signal separator 61 and an analogue-to-digital convertor 62 are contained in the main body block 20 as distinguished from the circuit arrangement of Figure 6.

The synchronizing signal separator circuit 61 separates the synchronizing signal from the composite signal which is supplied by a television signal receiving circuit comprising a tuner unit 40, a medium-frequency amplifier circuit 45 and a video signal detector-and-amplifier circuit 46, and the analogue-to-digital convertor 62 converts the video signal to corresponding digital signal.

On the other hand, the hinged lid 15 contains all the circuits that appear in the hinged lid of Figure 6 except for the synchronizing signal separator 61 and the analogue-to-digital convertor 62. Specifically, the hinged lid 15 contains a control signal generator 71 responsive to the synchronizing signal from the synchronizing signal separator 61 for providing different timing signals; a serial-to-parallel convertor 72 responsive to the digital signal supplied by the analogue-to-digital convertor 62 for performing a parallel conversion according to appropriate timing signals from the control signal generator 71; a line memory 73 for storing signals from the serial-to-parallel convertor circuit 72 under the control of appropriate timing signals; a sweep driver 74 for providing sweep signals to a liquid crystal display 14 under the control of appropriate timing signals; and a liquid crystal driver circuit 75 responsive to signals from the line memory 73 for providing image signals to the liquid crystal display 14 under the control of appropriate timing signals. These circuits are made in the form of IC chips 26.

The feature of the second embodiment which is different from the first one is referred to above, and other features are the same as the first one and therefore detailed description is omitted.

The structure of the present invention allows rays of light to pass through a light diffusing plate and fall on a liquid crystal display, permitting a mirror to reflect an image appearing in the liquid crystal display. This unique structure assures the presentation of bright clear images in the liquid crystal display.

Separation of many circuits and units in two blocks - the first body block to which a tuner unit, a mirror, etc., are allotted; and the second body block to which a light diffusing plate, a liquid crystal display, a synchronizing signal separtor, an analogue-to-digital convertor, driver circuits, etc. are allotted -- and electrical connection of these blocks are effective to reduce the whole size to a possible minimum.

As for the connector between the first and second blocks, a possible smallest number of signals are sent over the connector, and accordingly the number of conductors in the connector is limited to a small figure. Thus, a signal connector may be used, and accordingly the reliability for connection and signal transmission is improved. Also, advantageously the shielding of the connector may be performed with ease.

A part of the connector between the first and second blocks is exposed, and therefore noise signals are likely to invade the circuits in these blocks.

In this respect the circuit arrangement in the second embodiment is less susceptible to noise signals; the first block contains a synchronizing signal separator 61 and an analogue-to-digital convertor 62, and therefore pulse and digital signals which are much less susceptible to noise disturbance than analogue signals are directed from the first block to the second block. Thus, a simple shielding is adequate to avoid noise disturbance.

The light diffusing plate 13 is shown as an independent member in Figures 4 and 5. The upperframe 21, however, may be modified to take a part of the light diffusing plate 13. Otherwise, the light diffusing plate 13 and the upper polarizing plate 18 may be integrally connected.

As for a liquid crystal display used, a twisted ne matic type X-Y matrix display, a guest-and-host type X-Y matrix display, a transparent type or active matrix and other liquid crystal displays appropriate for the purpose may be equally used.

The audio section 47 and the speaker 36 may be provided to the hinged lid block 15 rather than the main body block 12.

The IC chips are shown as being attached to the cell substrate of the liquid crystal display 14. Alternatively an extra circuit board of an FPC or any other appropriate material may be provided to the hinged lid 15 to attach the IC chips thereto. Still alternatively, the driver circuits 66 and 67 may be attached to the cell substrate of the liquid crystal display 14 whereas the synchronizing signal separator circuit 61, the analogue-to-digital convertor 62, the control signal generator 63, the serial-toparallel convertor 64, the line memory 65 etc. may be attached to an extra circuit board provided in the hinged lid 15.

In Figure 6 the medium-frequency amplifier circuit 45 and the video detector-and-amplifier circuit 46 may be shifted to the hinged lid 15, if occasions demand.

The liquid crystal television according to the present invention can be of both black and white television and colour television.

It is also to be understood that the idea of the present invention can be applied to a liquid crystal television of dot sequential scanning system in which thin film transistors are used.

While the present invention has been described with reference to the preferred embodiments thereof, it will be understood that any modification may be made within the scope of the following claims. For example, although specific reference has been made to the reflective surface being in the form of a mirror 11, the reflective surface may be polished metal or a substrate bearing the reflective surface.

Claims

1. A liquid crystal television including a light transparent liquid crystal display unit, a reflective surface for presenting a reflection of an image transmitted from the liquid crystal display unit and means for adjusting the relative angular positions of the liquid crystal display unit and the reflective surface so as to concentrate the reflected image.

2. A liquid crystal television comprising a first body block including a reflective surface on its upper portion and at least a tuner unit for receiving a television signal, a second body block including a light diffusing plate, a light-transparent type liquid crystal display associated with the second body block and at least one circuit for driving the liquid crystal display, connector means for establishing electrical connection between the electrical circuits contained in the first and the second body blocks thereby permitting rays of light to pass to the liquid crystal display via the light diffusing plate and permitting the reflecting surface to reflect an image appearing in the liquid crystal display, thus presenting a reflection of the image to the eye.

3. A liquid crystal television according to Claim 2, wherein the second body block includes a synchronizing signal separator circuit responsive to the signal supplied from the first body block via the connector means for separating the synchronizing signal from the television signal and an analogue-to-digital convertor circuit for producing a video-signal in a digital form.

4. A liquid crystal television according to Claim 2 wherein the first body block includes a synchronizing signal separator circuit responsive to the signal from the tuner unit for selecting the synchronizing signal therefrom, and an analogue-todigital convertor circuit for producing a video-signal in a digital form.

5. A liquid crystal television according to Claim 2 wherein the second body block includes sealing means for holding said liquid crystal display in an air-tight condition.

6. A liquid crystal television according to Claim 5, wherein the sealing means comprises a waterproof packing disposed between an upper frame and a lower frame, between which the liquid crystal display is sandwiched.

7. A liquid crystal television according to Claim 6, wherein the connector extends through said water-proof packing connector.

8. A liquid crystal television according to Claim 7 wherein the upper and the lower frames are made from a transparent synthetic resin.

9. A liquid crystal television according to Claim 8, wherein the upper and the lower frames are covered by metal plates each having a window opening in conformity with the display area of the liquid crystal display.

10. A palm-sized liquid crystal television according to any preceding claim.

11. A palm-sized liquid crystal television constructed and arranged substantially as hereinbefore described with reference to and as shown in any one of Figures 3 to 7.