EP0604216B1

EP0604216B1 - Liquid crystal display device

Info

Publication number: EP0604216B1
Application number: EP19930310424
Authority: EP
Inventors: Chikahiko Murata; Katsuya Mizukata; Yukihiro Nakahara
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 1992-12-22
Filing date: 1993-12-22
Publication date: 1998-09-09
Anticipated expiration: 2013-12-22
Also published as: EP0604216A2; DE69320929D1; JPH06189233A; DE69320929T2; EP0604216A3

Description

The present invention relates to a liquid crystal display device used preferably as a display part of various apparatuses.

The liquid crystal display device can be formed in a smaller depth regardless of the display screen size as compared with the conventional display device using a cathode-ray tube. Additionally the liquid crystal display device is light in weight and small in power consumption. In spite of these excellent benefits, since liquid crystal molecules have a specific orientation, a viewing angle region where a favorable display image is observable is extremely limited.

That is, for example, when the TN type is used as the display element for composing a liquid crystal display device, the orientation processing of the substrate is done by rubbing method which enables to mass-produce the display element, in order to obtain an excellent display contrast, and a material possessing chirality of TN orientation complementary to a vector (groove direction) of a microgroove structure formed on the substrate surface by orientation processing is used as a liquid crystal material to be sealed between substrates.

Liquid crystal molecules are twisted in 90 degrees between two glass substrates of a TN type liquid crystal display device. Microgrooves are formed on a surface of each substrate on the liquid crystal side in a certain direction, which is at right angles to each other direction of the microgrooves of each substrate surface. The microgrooves are usually formed by application of rubbing treatment on a surface of a resin film formed on each substrate. A liquid crystal material which is prepared by mixing liquid crystal molecules with a material for giving chirality is disposed between such substrates. The liquid crystal molecules of the liquid crystal material arranged in the microgrooves have a character that they incline to the substrate face. Therefore, that material is employed as a material for giving chirality, which can compensate for insufficiency of twisting of the liquid crystal molecules of the twisted nematic liquid crystal in 90 degrees by twisting thereof through the directions of the microgrooves.

In such display element, however, the orientation direction of liquid crystal molecules depends on the rubbing direction of the substrate surface, and the chirality is determined by the liquid crystal material. Hence the viewing angle region where a favorable display contrast is obtainable is limited, and in other viewing angle, especially when the viewing angle is set on the opposite side of the favorable viewing angle, the visible range is virtually too narrow to observe.

A solution for expanding the viewing angle region is to improve the liquid crystal material and orientation technology, but at the present no one has succeeded in development of the device where a favorable display image is observable from any viewing direction, such as the cathode ray tube. In fabrication of liquid crystal display device, hence, it is indispensable to match the favorable viewing angle region with the viewing angle direction of the highest frequency of observation.

Hitherto, it is impossible to observe a favorable display image from a viewing angle on the opposite side of the viewing range of an image display panel, only with an image display panel (liquid crystal display means) where an orientation of the liquid crystal to the display screen is processed in the positive direction depending on the position of installation of the liquid crystal display device relative to the point of observation. Therefore, even if liquid crystal display devices with the same functions, shape and dimensions, i.e. liquid crystal display devices of the same model, are mass-produced, it is necessary to produce a panel where a favorable display image is observable from the opposite side viewing angle, that is, a panel where the orientation of the liquid crystal to the display screen is processed in the reverse direction, and hence two panels are required in total.

As a practical example thereof, in a liquid crystal display device for car-mount application, the panel is properly used in correspondence to a viewing angle which is determined by an observation point and a position of device installation. That is, the panel to be used for installation in the region around a central console which is located below a driver's eye level is reverse in viewing angle to that to be used for suspending from a ceiling above the eye level.

Fig. 1 is an illustration for showing a definition of the viewing range. When a panel is viewed from a display surface side, and an upper part is considered as twelve o'clock direction and a lower part as six o'clock direction. A panel of six o'clock viewing angel means a panel where a preferable display can be observed in a direction of six o'clock. On the other hand, a panel of twelve o'clock viewing angle means a panel where a preferable display can be observed in direction of twelve o'clock.

Thus, even in the liquid crystal display devices of the same model, two types of panels must be prepared, which leads to not only problems in a manufacturing process, product control or cost, but also inconvenience and disadvantages that users might purchase by mistake the apparatus where a preferable display cannot be recognized at a desired position of installation.

GB-A-2 216 703, on which the preamble of claim 1 is based, discloses a liquid crystal display device comprising a plurality of signal electrodes and a plurality of scanning electrodes, the signal electrodes being crossed with the scanning electrodes. The display device can display an image either as the normal image or as its mirror image.

The present invention provides a liquid crystal display device comprising: a main body composed of a liquid crystal display means possessing a plurality of signal electrodes and a plurality of scanning electrodes intersecting the signal electrodes, and driving means for driving the liquid crystal display means so as to form either a first image or a second display image on the liquid crystal display means on the basis of a video signal;
characterised in that the second image is the first image rotated about a point in the first image by 180 degrees;

and in that the display device further comprises: positioning means for selectively fixing the main body either in a first position where a viewing angle for observing the image displayed on the liquid crystal display means from a predetermined observation point is included in an observable viewing angle region determined by a liquid crystal orientation of the liquid crystal display means in a predetermined first posture or in a second position where the viewing angle for observing the display image from the observation point is included in the observable viewing angle region of the liquid crystal display means in a second posture, the second posture being obtained by rotating the liquid crystal display means in the first posture by about 180 degrees about the normal to the display surface of the liquid crystal display means in the first posture; and

posture holding means for selectively holding the main body in either the first posture or the second posture, the posture holding means being supported by the positioning means.

In a preferred embodiment the driving means comprises a signal electrode drive circuit for scanning a plurality of signal electrodes, a scanning electrode drive circuit for scanning a plurality of scanning electrodes, and an inversion control circuit for inverting the scanning directions of the signal electrode drive circuit and scanning electrode drive circuit.

In a preferred embodiment the positioning means comprises:

a bar-shaped post member, support means for supporting the post member in a vertical direction on a plane of installation such as a floor or a ceiling, the support means being disposed at a first end of the post member, and connecting means for connecting the second end of the post member to the main body.

In a preferred embodiment the connecting means comprises: a dovetail tenon disposed on one of the second end of the post member or the main body, and a connection member possessing a complementary dovetail groove for receiving the dovetail tenon, the connection member being disposed on the other of the second end of the post member or the main body.

In a preferred embodiment the connecting means is composed of a threaded hole formed in one of the second end of the post member or the main body, and a bolt to be screwed, in use, into the threaded hole is provided at the other of the second end of the post member or the main body.

In a preferred embodiment a protrusion is formed on one of the dovetail tenon or the connection member, and a recess in which the protrusion is fitted, in use, is formed in the other of the dovetail tenon or the connection member.

In a preferred embodiment the connecting means functions as the posture holding means by connecting a side of the main body with the second end of the post member such that the side is either on an upper side of an image displayed on the liquid crystal display means or on a lower side of the image.

In a preferred embodiment the connecting means functions as the posture holding means by selectively connecting a side of the main body with the other end of the post member such that the side is either on a left side of an image displayed on the liquid crystal display means or is on a right side of the image.

In a preferred embodiment the positioning means comprises two post members differing in length.

In a preferred embodiment the post member is expandable in length.

In a preferred embodiment the positioning means comprises: a guide member including first and second guide posts disposed parallel to each other, wherein the first and second guide grooves are formed in mutually confronting surfaces of the respective guide posts; and a slide plate having an engagement piece to be engaged slidably with the guide grooves, the slide plate being disposed on the back side of the main body;

wherein the guide member comprises position holding means disposed on the guide posts, for holding the engagement pieces and fixing the main body in the first or second position.

In a preferred embodiment the posture holding means comprises:

a circular protruding portion formed on the back side of the main body; and a hole formed in the slide plate, the circular protruding portion being fitted, in use in the whole; wherein one of the circular protruding portion and the slide plate is provided with a detent protrusion and an operating part for projecting and retracting the detent protrusion, and wherein detent holes in which the detent protrusion fits, in use, are formed at two positions differing in phase by 180 degrees from each other in the other of the circular protruding portion or the slide plate.

Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:

Fig. 1 is an illustration for showing a definition of a viewing range;

Fig. 2 is a schematic side view showing an embodiment of the invention.

Fig. 3 is a sectional view schematically showing the main body of the device.

Fig. 4 is an essential magnified perspective view schematically showing the structure of a display panel.

Fig. 5 is a schematic wiring diagram showing an electric configuration of the display panel and driving means thereof.

Fig. 6 is a schematic view showing a pixel arrangement of the display panel.

Fig. 7 is a schematic front view showing the display panel screen where a first display image is displayed.

Fig. 8 is a schematic front view showing a display panel screen where a second display image is displayed.

Fig. 9 is an exploded perspective view showing an example of positioning means and posture holding means.

Fig. 10 is a schematic perspective view showing other embodiment of the invention.

Fig. 11 is a schematic rear view showing other embodiment of the invention;

Figs. 12(1) and 12(2) are sectional views showing a structure of position holding means 24a;

Fig. 13 is a magnified plan view of the position holding means;

Fig. 14 is a sectional view taken on line A-A of Fig. 13;

Fig. 15 is a schematic front view showing a first display image in other example of display mode.

Fig. 16 is a schematic front view showing a second display image.

Fig. 17 is a schematic view showing a constitution of top and bottom judging means;

Fig. 18 is a schematic view showing a constitution example of the device in the case of utilizing a remote control system.

Now referring to the drawing, preferred embodiments of the invention are described below.

Figs. 2 to 9 relate to an embodiment of application of the invention in a liquid crystal display device of a relatively large screen. As schematically shown in Fig. 2, the device of this embodiment comprises a main body 1 and positioning means 2 for the main body 1. The main body 1 comprises, as schematically shown in Fig. 3, a display panel 4 as liquid crystal display means provided in a main body outer shell 3, various control parts, operating parts (not shown), and others.

In this embodiment, the display panel 4 is constituted by including a liquid crystal panel 34 of active matrix type TFT (thin film transistor) system. That is, in the liquid crystal panel 34, two glass substrates 5a, 5b are disposed to be opposite to each other, a common electrode 6 composed of a transparent conductive film and an orientation film (not shown) are disposed on the surface of the substrate 5a on the panel front side which confronts the surface of the other substrate 5b, and a TFT switch matrix 7 and an orientation film (not shown) are provided on the confronting surface of the substrate 5b on the rear side, and a nematic liquid crystal layer 8 is sealed between the substrates 5a, 5b, more strictly between the orientation films so that the common electrode 6 and the TFT switch matrix 7 confront each other, and moreover polarizing plates are disposed on the outer surfaces of the substrates 5a, 5b. Furthermore, as required, backlight means 9 is disposed behind the rear side substrate 5b.

In the TFT switch matrix 7, as the main portion is schematically shown in Fig. 4, plural signal electrodes S and plural scanning electrodes G orthogonally crossing the signal electrodes S are disposed in matrix on the rear side substrate 5b, and a pixel electrode P and a TFT switch for connecting and disconnecting application of voltage to the pixel electrode P are disposed in the proximily of an intersection of the signal electrodes S and scanning electrodes G.

In this TFT switch T, a semiconductor thin film 10 is used as a channel, and a signal electrode S as a source electrode and a pixel electrode G as a drain electrode are connected at both ends of the semiconductor thin film 10, and a gate electrode 11 extended from the scanning electrode G is opposite to the semiconductor thin film 10 through an insulation film 12.

Fig. 5 schematically shows an electric configuration of driving means 13, and Fig. 6 schematically shows an arrangement of electrodes S, G, P of the TFT switch matrix 7 and the TFT switch T. Fig. 7 shows a first display image 14a formed on a display panel 14 by the driving means 13 described below, and Fig. 8 shows a second display image 14b rotating the first display image by 180 degrees from a given point (O) in the first display image 14a. More specifically, the second display image 14b shown in Fig. 8 is obtained by rotating 180 degrees from the center point (O) of the first display image 14a, and the images are symmetrical vertically about the lateral center line L1 of the screen.

In Fig. 5, the TFT liquid crystal panel 34 is structured as shown in Fig. 4, and the pixel electrodes P are arranged as shown in Fig. 6. This TFT liquid crystal panel 34 comprises, as shown in Fig. 6, plural parallel signal electrodes S₁-S_n (hereinafter called source bus lines), plural parallel scanning electrodes G₁-G_m (hereinafter called gate bus lines) which are orthogonal therewith, and matrix plural pixel electrodes P₁₁-P_mn connected through driving switching elements T₁₁-T_mn (TFT).

The driving means 13 comprises a video signal processing circuit 31 processing a complex video signal externally outputted, a source driver 32 controlling source bus lines S₁-S_n, a gate driver 33 controlling gate bus lines G₁-G_m, and an inversion control circuit 35 controlling the scanning sequence of the gate bus lines G₁-G_m and the inversion of the sequence of video signal application to the source bus lines S₁-S_n.

The video signal processing circuit 31 comprises a processing circuit 36 and a control circuit 37. The processing circuit 36 separates video signals and synchronizing signals (a horizontal synchronizing signal and a vertical synchronizing signal) from complex video signals. The video signal is transmitted to the source driver 32 and the synchronizing signal to the control circuit 37. The control circuit 37 generates various control signals for controlling the source driver 32 and gate driver 33 to output to the source driver 32 and gate driver 33.

The source driver 32 comprises a bidirectional shift register 38, a sample holding circuit 39 and an output buffer 40. The bidirectional shift register 38 outputs a start pulse SPD transmitted from the control circuit 37 to the sample holding circuit 39, shifting successively in timing when a clock signal CLD transmitted from the control circuit 37 is inputted. The sample holding circuit 39 samples and holds a video signal transmitted from the processing circuit 36 in timing of outputted pulse from the bidirectional shift register 38 and outputs the holded video signals all at once to the output buffer 40 in response to a control signal from the control circuit 37 at the point of the time when all the video signals corresponding to the source bus lines S₁-S_n have been holded. The output buffer 40 outputs the transmitted video signals to each of source bus lines S₁-S_n.

The bidirectional shift register 38 comprises a forward shift register 41, a backward shift register 42, output change-over means 43 for outputting from either of two shift registers 41, 42, and input change-over means 44 for inputting to either of the two shift register 41, 42.

The forward shift register 41 is composed of n pieces of flip-flops CF₁-CF_n. The clock signal CLD is transmitted to each CK input of the flip-flops CF₁-CF_n in common to all the flip-flops. The start pulse SPD is inputted via the input change-over means 44 to a D input of the flip-flop CF1. A Q output from the flip-flop CF_i (i=1-n) is transmitted to the output change-over means 43 and the D input of the flip-flop CF_i+1.

The backward shift register 42 is composed of n pieces of flip-flops CR₁-CR_n. The clock signal CLD is transmitted to each CK input of the flip-flops CR₁-CR_n in common to all the flip-flops. The start pulse SPD is inputted via the input change over means 44 to a D input of the flip-flop CR_n. A Q output from the flip-flop CR_i (i = n-1) is trnsmitted to the output change-over means 43 and the D input of the flip-flop CR_i-1.

The output change-over means 43 is composed of n pieces of switches E₁-E_n. The switches E₁-E_n change connection from between a common contact C and a contact A to between the common contact C and a contact B or vice versa in response to a change-over signal L/R from the inversion control circuit 35. The contact A of the switch E_i (i=1-n) is connected to the Q output of the flip-flop CF_i, the contact B is connected to the Q output of the flip-flop CR_i, and the contact C is connected to a sample holding circuit 39.

The input change-over means 44 is embodied by a switch. The switch changes connection from between the common contact C and the contact A to between the common contact C and the contact B or vice versa in response to a change-over signal L/R. The contact A is connected to a D input of the flip-flop CF₁, the contact B to a D input of the flip-flop CR_n, and the start pulse is given to the contact C.

The gate driver 33 comprises a bidirectional shift register 45, a level shifter 46 and an output buffer 47. The bidirectional shift register 45 outputs a start pulse SPS transmitted from the control circuit 37 to the level shifter 46, shifting successively in timing when a clock signal CLS transmitted from the control circuit 37 is inputted. The level shifter 46 increases a potential of an inputted pulse up to a given potential and outputs as a scanning signal to the output buffer 47. The output buffer 47 outputs the transmitted scanning signal to each of the gate bus lines G₁-G_m.

The bidirectional shift register 45 comprises a forward shift register 48, a backward shift register 49, output change-over means 50, and input change-over means 51. The output change-over means 50 changes over from outputting from the shift register 48 to that from the shift register 49 or vice versa. The input change-over means 51 changes over from inputting to the shift register 48 to that to the shift register 49 or vice versa.

The forward shift register 48 is composed of m pieces of flip-flops HF₁-HF_m. The clock signal CLS is transmitted to each CK input of the flip-flops HF₁-HF_m in common to all the flip-flops. The start pulse SPS is inputted via the input change-over means 51 to a D input of the flip-flop HR_m. A Q output from the flip-flop HF_i (i=m-1) is transmitted to the output change-over means 50 and the D input of the flip-flop HF_i+1.

The backward shift register 49 is composed of m pieces of flip-flops HR₁-HR_m. The clock signal CLD is transmitted to each CK input of the flip-flops HR₁-HR_m in common to all the flip-flops. The start pulse SPD is inputted via the input change over means 51 to a D input of the flip-flop HR_n. A Q output from the flip-flop HR_i (i = m-1) is trnsmitted to the output change-over means 50 and the D input of the flip-flop HR_i-1.

The output change-over means 50 is composed of m pieces of switches J₁-J_m. The switches J₁-J_m change connection from between a common contact C and the contact A to between the common contact C and the contact B or vice versa in response to a change-over signal L/R from the inversion control circuit 35. The contact A of the switch J_i (i=i-m) is connected to the Q output of the flip-flop HF_i, the contact B is connected to the Q output of the flip-flop HR_i, and the contact C is connected to the level shifter 46.

The input change-over means 51 is embodied by a switch. The switch changes connecting from between the contact C and the contact A to between the contact C and the contact B or vice versa in response to the change-over signal L/R. The contact A is connected to a D input of the flip-flop HF₁, the contact B is connected to a D input of the flip-flop HRm, and the start pulse SPS is given to the contact C.

The inversion control circuit 35 comprises a switch 52. A constant voltage VDD is applied to one terminal of the switch 52, and the other terminal of the switch 52 is connected via a resistance 53 to a ground potential. The potential of the other terminal of the switch 52 is outputted as a change-over signal L/R. The switch 52 may be an electrical or mechanical one.

When a pulse for turning on the TFT is applied to the gate bus line, the voltage applied to the TFT is applied to the pixel electrode, and the light is controlled by driving the liquid crystal by the potential difference thereof from the voltage applied to the confronting common electrode.

Scan inversion of signal electrodes and scanning electrodes is described below with reference to the pixel arrangement schematic diagram in Fig. 6. The diagram relates to the active matrix type TFT system, one side installation of a source and a gate driver, and stripe arrangement, but the invention may be also applied in other liquid crystal driving systems, driver arrangements, and pixel arrangement systems.

Usually, the liquid crystal driving signal voltage given to the liquid crystal through pixel electrodes P₁₁-P_mn is applied in the sequence of P₁₁ → P₁₂ ... → P_1·n-1→P_1n → P₂₁→P₂₂ ... →P_2·n-1→P_2n ... →P_m·n-1 → P_mn, depending on the timing of the video signal voltage applied from the source driver to the source bus lines S₁-S_n, and the scanning signal applied from the gate driver to the gate bus lines G₁-G_m. On the other hand, the image is inverted vertically and laterally by inverting the scanning direction of the source driver and gate driver S_n→S₁, G_m→G₁ respectively, thereby applying the voltage in the sequence of P_mn→P_m·n-1...→P_m2→P_m1→P_m-1·n...→P_m-1·2→P_m-1·1... P₁₂→P₁₁.

In the case where an non-inverted picture is displayed on a liquid crystal panel 34, a change-over signal L/R is changed to be in the high level state by turning on the switch 52 of an inversion control circuit 35 and the switches 44, E₁-E_n are switched to the contact A side. Thereby, the start pulse SPD is inputted into flip flop CF₁ consisting the forward shift register 41. At the time, the clock signal CLD is inputted. Thereby the start pulse is latched, outputted as Q output, and outputted to the sample holding circuit 39 through the switch E1. Start pulses SPD are outputted sequentially from flip flop CF₂-CF_n to the sample holding circuit 39 at an interval of a one pulse of the clock signal CLD.

The switches 51, J₁-J_m are switched to the contact A by a high level change-over signal L/R. Thereby, the start pulse SPS is inputted to flip-flop HF₁ constituting the forward shift register 48. At the time, if the clock signal CLS is inputted, the start pulse SPS is latched, outputted as Q output, and outputted to the level shifter 46 via the switch J₁. Start pulses SPS are outputted sequentially from the flip-flop HF₂-HF_m to the level shifter 46 at the interval of a one pulse of the clock signal CLS.

Therefore, according to Fig. 6, while a pulse corresponding to one horizontal period (horizontal period pulse) is applied from the gate driver 33 to the gate bus line G₁, the video signal voltage applied from the source bus line S₁ to S_n is sequentially written into the pixel electrodes of the first line depending on the potential difference from the common electrode voltage, and in the next horizontal period, as a horizontal period pulse is applied to the gate bus line G₂, the TFT of the second line is turned on, while the video signal voltage applied from the source bus lines S₁ to S_n in this period is written into the pixel electrodes of the second line. By repeating likewise up to the gate bus line G_m, a picture (an image) is displayed on the liquid crystal panel 34.

On the other hand, in the case where an inverted picture is displayed on the liquid crystal panel 34, the change-over signal L/R is changed to be in the low level state by turning off the switch 52 of the inversion control circuit further, each of the switches 44, E₁-E_n is switched to the contact B side. Thereby, the start pulse SPD is inputted into the flip-flop CR_n constituting a backward shift register 42. At the same time, by inputting the clock signal CLD, the start pulse SPD is latched, outputted as Q output and outputted via the switch E_n to the sample holding circuit 39. Thereafter, the start pulses SPD are outputted sequentially from the flip-flops CR_n-1-CR₁ to the sample holding circuit 39 at a time interval of a one pulse of the clock signal CLD.

Further, the switches 51, J₁-J_n are switched to be on the contact B side by the change-over signal L/R of low level. Thereby, the start pulse SPS is inputted to the flip-flop HR_m constituting a backward shift register 49. At the same time, the clock signal CLS is inputted, thereby the start pulse SPS is latched, outputted as Q output, and outputted to the level shifter 46 via the switch J_m. Thereafter, the start pulses SPS are outputted sequentially from the flip-flops HR_m-1-HR₁ at a time interval of a one pulse of the start pulse SPD is latched, outputted as Q output, and outputted to the clock signal CLS.

Therefore, according to Fig. 6, while a pulse corresponding to one horizontal period (horizontal period pulse) is applied from the gate driver 33 to the gate bus line G_m, the video signal voltage applied from the source bus line S_n to S₁ is sequentially written into the pixel electrodes of the m_th line depending on the potential difference from the common electrode voltage, and in the next horizontal period, as a horizontal period pulse is applied to the gate bus line G_m-1, the TFT of the m-1th line is turned on, while the video signal voltage applied from the source bus lines S_n to S₁ in this period is written into the pixel electrodes of the m-1th line. By repeating likewise up to the gate bus line G₁, a picture (an image) is displayed on the liquid crystal panel 34.

Therefore, by providing the shift registers 38, 45 of the source driver 32 and gate driver 33 with the bidirectional counter function and changing over by the switch or the like, the vertical and lateral inversion of image can be realized.

The liquid crystal panel 34 which composes the display panel 4 in the above-mentioned composition has an orientation film formed on each of the glass substrates 5a, 5b and subjected to orientation processing as mentioned in the description of the related art, and the liquid crystal layer 8 is composed of a liquid crystal material possessing a complementary chirality to the vector of the microgroove structure formed on the surface of the orientation film by the orientation processing. Therefore, the arrangement direction of liquid crystal molecules of the liquid crystal layer 8 is defined by the orientation film formed on the substrates 5a, 6b, which limit the viewing angle region capable of obtaining a favorable display contrast.

Circular patterns E1, E2 shown in Fig. 2 schematically show the viewing angle regions. Supposing the viewing angle region capable of observing the display panel 4 favorably is limited in a range indicated by hatched area of the whole viewing field, the display panel 4 is set at an upper setting position Pb as a first position capable of observing at a viewing angle b from observation point Pa, and the direction of the display panel 4 is set so that the viewing angle region A capable of observing favorably at this time may be in the lower half of the whole viewing field shown in pattern E1.

On the contrary, when the display panel 4 is set in a lower setting position Pc as a second position corresponding to a viewing angle c from a viewing point(a), at this lower setting position Pc, by rotating the display panel 4 by 180 degrees, the viewing angle region A2 shown in pattern E2 is reverse in direction to the viewing angle region A1 and is suited to observing the image favorably.

The device of the embodiment is composed on the basis of this point, and the main body 1 may be installed in either upper or lower position, and it is possible to observe in a viewing angle region capable of observing favorably at either position.

In Fig. 2, the positioning means 2 is constituted by including first and

second connection members

15a, 15b mounted on the upper and lower sides of the main body outer shell 3, and first and

second post members

16a, 16b differing in length.

These

post members

16a, 16b are selectively used depending on the mounting position of the main body 1, and the dimensions thereof are set so that the longer first post 16a may support the device main body 1 at the upper setting position Pb, and the shorter second post member 16b, at the lower setting position Pc. These

post members

16a, 16b are formed out of solid materials or tubular materials having a square or circular section with a sufficient strength for supporting the weight of the main body 1, and are fixed on a floor or the like in standing position with proper support means 13.

On the other hand, the first and

second connection members

15a, 15b are individually formed in block pieces, and fixed to the middle region of the upper and lower sides of the main body outer shell 3, or integrally formed in the middle of the upper and lower sides of the main body outer shell 3, being constituted to have additionally the function of posture holding means in this embodiment as mentioned below. Connecting means for connecting the

post member

16a or 16b and the

connection member

15a or 15b is formed on the upper ends of the first and

second post members

16a, 16b and the ends of the first and

second connection members

15a, 15b to be confrontingly connected therewith.

To form the connection means, for example,

dovetail grooves

17a, 17b are provided on the ends of the first and

second connection members

15a, 15b, as shown in Fig. 9, and dovetail tenons 18a, 18b to be fitted with the

dovetail grooves

17a, 17b are formed on the upper ends of the first and

second post members

16a, 16b, and a locking protrusion 59 and a stopping recess 60 to be engaged with each other in the completely fitted state of the both are formed in the

dovetail groove

17a or 17b and in the dovetail tenon 18a or 18b.

The mode of the connection means is not limited to such constitution alone, but other stopping structures and various forms such as screw tightening structure using screw hole in one side and a bolt in the other side may be realized.

In thus composed device of the embodiment, the main body 1 can be installed at either upper setting position Pb or lower setting position Pc. That is, when installed on the upper setting position Pb, the longer first post member 16a is fixed in standing position on the floor beneath the upper setting position Pb, and by engaging the dovetail 18a of the first post member 16a with the dovetail groove 17a of the first connection member 15a, the device main body 1 can be fixed and supported at the upper setting position Pb.

In this way, when the main body 1 is set at the upper setting position Pb, the viewing angle b for observing the display image of the display panel 4 upward from the observation point Pa is at a height of a position included in the observable viewing angle region A1 on the basis of the liquid crystal orientation of the display panel 4. In this case, by manipulating the driving means 13, it is set so that the first display image 14a which is an erected image shown in Fig. 7 may be always formed on the display panel 4.

When installed at the lower setting position Pc, the second shorter post member 16b is fixed in the standing position on the floor, and the main body 1 is turned upside down, and by engaging the dovetail tenon 18b of the second post member 16b with the dovetail groove 17b of the second connection member 15b, the main body 1 can be fixed and supported at the lower setting position Pc in the state that the main body 1 installed at the upper setting position Pb is turned upside down, that is, in the posture that the main body 1 is rotated by 180 degrees.

In this way, when the device main body 1 is set at the lower setting position Pc, the viewing angle c for observing the display image of the display panel 4 downward from the observation point Pa is at a height of a position included in the observable viewing angle region A2 of the display panel 4 being inverted.

In this case, when the first display image 14a is formed on the display panel 4, the image is recognized upside-down. Therefore, it is necessary to form the second display image 14b shown in Fig. 8 with the aid of the driving means 13. Since the second display image 14b is an inverted image of the first display image 14a, it can be observed as an erected image by forming an inverted image of the second display image 14b on the inverted display panel 4.

By coupling thus either one of the first and

second connection members

15a, 15b with the

post member

16a or 16b by the aid of the connection means, the main body 1 can be maintained, for example, in the first posture capable of observing the first display image 14a in the erected state thereof and in the second posture rotating 180 degrees from the first posture, so that the

connection members

15a, 15b are also provided with the function of the posture holding means.

According to the embodiment having such constitution, by selectively using either member of a set of long and

short post members

16a, 16b as the positioning means 2, the main body 1 can be disposed at either of the setting positions Pb, Pc as desired. The

post members

16a, 16b may be also mounted on the ceiling, instead of the floor, and the main body 1 may be supported in suspended state. Furthermore, the post members may be composed to be flexibly expandable.

Fig. 10 schematically shows the essential portion of other embodiment of the invention, and in this diagram, as the positioning means 2, a guide member 9 install in a standing state on a floor is provided, and the main body outer shell 3 is elevatably supported by the guide member 19.

That is, the guide member 19 is composed of a pair of

guide posts

20a, 20b which rise from the floor parallel to each other in a standing state and have a height capable of supporting the main body 1 at the upper setting position (2).

Guide grooves

21a, 21b are formed on the sides of the

guide posts

20a, 20b confronting each other. On the other hand, a slide plate 22 is disposed on the rear side of the main body outer shell 3, engaging pieces 23a, 23b to be slidably and elevatably engaged with the

guide grooves

21a, 21b are projected on the rear side of the slide plate 22, and proper position holding means 23a, 24b are provided at positions corresponding to the upper setting position Pb and lower setting position Pc of the

guide grooves

21a, 21b in order to hold the engaging pieces 23a, 23b at the positions.

Position holding means 24a and 24b have the same structure. As shown in Fig. 11, the position holding means 24a is disposed on the upper setting position Pb of the guide posts 20a and 20b and the position holding means 24b on the lower setting position C thereof. As an example, the position holding means 24a on a guide post 20a is explained.

A recess 81 is formed for disposing the position holding means 24a in guide post 20a. A hole 82 is formed in the lower side of the recess 81. The position holding means 24a is composed of rectangular parallelpiped portion 83, which is set and sunk in the recess 81, a protruding portion 84 formed in a surface 83a of the portion 83 and an engagement claw 85 formed on the surface 83a of the portion 83. The position holding means 24a is attached to the upper portion of the recess 81 in angularly disposable condition around the axis 86 formed on the protruding portion 84. The spring 87 is interposed between the surface 83a of the portion 83 and a bottom 81a of the recess 81. The spring 87 is selected so that the outside surface 83b of the portion 83 and the outside surface 88 of the guide post 20a are in parallel in the natural length of the spring 87. In the natural length of the spring 87, the end portion of the engagement claw 85 is not projected from the hole 82, the recess 90 into which the engagement claw 85 is inserted is formed on engagement piece 23a. The protrusion 91 which is projected downward is formed on the upper side of the recess 90.

When the main body 1 is vertically displaced, the engagement claw 85 is not projected from the hole 82 as shown in Fig. 12(1). Therefore, the engagement piece 23a is displaced flexibly in a vertical direction along the guide groove 21a.

When the main body 1 is locked, the position is adjusted so that the part of the recess 90 of the engagement piece 23a and the part of the hole 82 of the guide post 20a are confronted. In this condition, the outside surface 83b of the portion 83 of the position holding means 24a is pushed. Thereby, the position holding means 24a is angular-displaced around the axis 86, the engagement claw 85 is set in the recess 90, the end portion of the engagement claw 85 is hooked on the protrusion 91. At the time, the spring 87 is contracted. Therefore, the engagement claw 85 and the protrusion 91 are engaged firmly by the elastic force of the spring 87. Thus, the main body 1 is fixed.

The release operation of the engagement is as follows. That is, the engagement between the engagement claw 85 and the protrusion 91 is released when the engagement piece 23a is displaced upwardly in a vertical direction. The position holding means 24a is angular-displaced by the elastic force of the spring 87, and returns to the original condition as shown in Fig. 12(1).

In thus composed positioning means 2, by elevating the main body 1 along the guide member 19 and manipulating the upper position holding means 24a, the main body 1 can be fixed and supported at the upper setting position Pb, and by lowering the main body 1 along the guide member 19 and manipulating the lower position holding means 24b, the device main body 1 can be fixed and held at the lower setting position Pc.

In this embodiment, the posture holding means is composed separately from the positioning means 2. That is, the posture holding means 25 is provided with a circular protruding portion 26 projecting in the middle of the rear side of the main body outer shell 3, and a fitting hole 27 of the nearly same diameter as that of the circular protruding portion 26 is formed in the slide plate 22, and the circular protruding portion 26 of the main body outer shell 3 is rotatably fitted in the fitting hole 27 in the slide plate 22. Moreover, a detent protrusion 28 and an operating part 29 for projecting/retracting the detent protrusion 28 are provided at a proper position of either the circular protruding portion 26 or fitting hole 27, and

detent holes

30a, 30b are formed at two positions differing in phase by 180 degrees from each other in the other thereof.

Fig. 13 is a drawing for showing an enlarged plan view of the position holding means 25. Fig. 14 is a sectional view seen from the section line A-A of Fig. 13. The L-shaped detent member 93 is attached to the circular protrunding portion 26. The detent member 93 is composed of the detent protrusion 28 and the operation part 29. The detent protrusion 28 is inserted through the insertion hole 95 formed on the circular protruding portion 26, the end portion of the detent protrusion 28 is protruded out of the side of the circular protruding portion 26 due to the elastic force of the spring 94. The operation part 29 is protruded outside from a long hole 92 communicating with the insertion hole 95. The protruded detent protrusion 28 is inserted into the detent hole 30a formed on the slide plate 22, whereby, the main body 1 is held.

The detent protrusion 28 is sunk in the circular protruding portion 26 by displacing the operation part 29 to the center 0 direction of the circular protruding portion 26. In this condition, the main body 1 can be rotated in relation to the slide plate 22. When the main body 1 is rotated in the above manner and the detent protrusion 28 is displaced to the position of the detent hole 30b, the end portion of the detent protrusion 28 is inserted into the detent hole 30b due to the elastic force of the spring 94, the main body 1 is held in the inverted condition.

In the posture holding means 25 thus composed, when the main body 1 is located at the upper setting position Pb, by putting the detent protrusion 28 into one detent hole 30a, the device main body 1 is held in standing position. When the device main body 1 is located at the lower setting position Pc, the engagement between the detent protrusion 28 and one detent hole 30a is released by manipulating the operating part 29, and the main body 1 is rotated 180 degrees around the circular protruding portion 26, and then the operating part 29 is manipulated again to put the detent protrusion 28 into the other stopping hole 30b, thereby the main body 1 is held in an inverted posture.

According to thus composed embodiment, it is effective to install in a facility possessing a space for installation so that the mounting position of the main body 1 may be selected at either upper or lower position. By partly modifying the device of the embodiment, it may be also applied to a type capable of selecting the setting position right and left.

This type of device is preferable in the case where the first and second display images are vertically symmetrical images, for example, as shown in Fig. 15 and Fig. 16, and the direction of right and left does not matter in particular. In such a case, relative to the first display image 14a shown in Fig. 15, the second display image 14b shown in Fig. 16 as an image rotated by 180 degrees about the image center point (O) is a laterally inverted image which is symmetrical about the lateral center line L2 of the screen.

By employing a liquid crystal orientation direction of the display panel 4 where the viewing angle region for observing ranges in the lateral direction and disposing the guide member 19 in the horizontal direction for forming the image inverted in the lateral direction, a laterally displaceable type of the device may be easily composed in the other embodiment mentioned above.

The positioning means and posture holding means as comprising elements of the invention may be modified in various types aside from the foregoing embodiments. Moreover, in the above-mentioned embodiments, the display image may be automatically rotated by 180 degrees by providing the driving means 13 with means for judging the top and bottom of the display image and interlocking the judging means with the posture holding means.

When such judging means is employed in the first embodiment mentioned above, the judging means is constituted so that the first display image 14a is automatically formed on the display panel 4 when either one of the first and

second connection members

15a, 15b is connected to the

post member

16a or 16b, and the second display image 14b is formed when the other thereof is connected to the

post member

16a or 16b. In other embodiment, the judging means is constituted so that the first display image 14a may be formed automatically when the detent protrusion 28 gets into either one of the detent holes 30a and 30b of the posture holding means 25, and that the second display image 14b is formed when getting into the other.

Fig. 17 is a drawing for showing the concrete structure of top and bottom judging means. Hereafter, the embodiment shown in Fig. 17 is explained as an example.

Switches

55 and 56 are attached to the

dovetail tenons

17a and 17b, respectively. These

switches

55 and 56 are conducted by connecting the dovetail grooves 18a and 18b to the

dovetail tenons

17a and 17b. The detecting circuit 67 switches the low level/high level of the change-over signal L/R on the basis whether or not the

switches

55 and 56 are conducted. Thus, in Fig. 17, the inversion control circuit 35 shown in Fig. 5 as mentioned above includes the

switches

55 and 56, and the detecting circuit 57. Therefore, the image displayed at the time when the switch 55 is conducted and the image displayed at the time when the switch 56 is conducted are inverted mutually.

Furthermore, in other embodiments, comprising an external remote control device, position detecting means for detecting first and second positions by the direction of the signal from the external remote control device, driving means for driving the posture holding means 25 on the basis of the signal from the position detecting means, and means for driving the driving means 13 on the basis of the signal of the position detecting means, only by manipulating the external remote control device, the main body 1 is rotated automatically, and the first and

second display images

14a, 14b may be changed over.

Further, it is possible to control the inversion of the image and the rotation and vertical movement of the main body by utilizing a remote control system.

Fig. 18 is a schematic view showing a constitution example of the device in the case of utilizing the remote control system. The constitution will be described by way of example with reference to the embodiment shown in Fig. 18. When the main body 1 is positioned in the upper position, a switch 62 of an external remote control device 61 is pushed. Thereby, the external remote control device 61 transmits a predetermined signal. The transmitted signal is received by a receiving portion 63 of the signal from the remote control device 61. The received signal is transmitted to a control circuit 64. The control circuit 64 drives a motor 65. The motor 65 drives a gear 67 built in the engagement piece 23a toward a direction of an arrow 69. The gear 67 is engaged with a tooth 68 formed in the groove 21a of the guide post 20a. Therefore, the main body 1 moves downward.

At the time, the control circuit 64 drives also a motor 66. The motor 66 rotates a gear 70 built in the circular protruding portion 26 of the main body outer shell 3. The gear 70 is engaged with a tooth formed on an inner side of the engagement hole 27 of the slide plate 22. Therefore, the main body 1 rotates about the circular protruding portion 26.

The engagement piece 23a moves downward along the guide post 20a and contacts with a switch 72 arranged at a lower end of the groove 21a of the guide post 20a. Thereby, the switch 72 is electrically conducted. The control circuit 64 detects the conduction of the switch 72 and stops the motor 65. Thereby, the main body 1 stops at the lower position of the guide post 20a. The gear 70 rotates along the tooth 71 and contacts with the switch 73. Thereby the switch 73 is electrically conducted. The control circuit 64 detects the conduction of the switch 72 and stops the motor 66. Thereby the main body 1 is inverted.

Further, in this condition, the control circuit 64 switches the level of the change-over signal L/R. Thereby the image displayed on the liquid crystal panel 34 is inverted. Thus, an observer can view a preferable image because the viewing angle in the case of the main body positioned in the upper position of the guide member 19 is the inverse of that in the case of the main body positioned in the lower position thereof.

When the main body 1 is displaced from the lower position to the upper position, a switch 74 of the external remote control device 61 is pushed. Thereby the control circuit 64 drives the motor 65 and rotates the gear 67 toward a direction of an arrow 75 (reverse of the direction of the arrow 69). Therefore, the main body 1 moves upward. At the time, the control circuit 64 drives the motor 66 and rotates the gear 70. Therefore, the main body 1 rotates about the circular protruding portion 26.

The engagement piece 23a moves upward along the guide post 20a and contacts with a switch 76 arranged at an upper end of the groove 21a of the guide post 20a. Thereby the switch 76 is electrically conducted. The control circuit 64 detects the conduction of the switch 76 and stops the motor 65. Thereby the main body 1 stops at the upper position of the guide post 20a. Further, the gear 70 rotates along the tooth 71 and contacts with a switch 77. Thereby the switch 77 is electrically conducted. The switch 77 is arranged at a position confronting the switch 73 by 180 degrees. The control circuit 64 detects the conduction of the switch 77 and stops the motor 66. Thereby the main body 1 is inverted. Further, in this condition, the control circuit 64 switches the level of the change-over signal L/R. Thereby an image displayed on the liquid crystal display panel 34 is inverted.

The invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the scope of the following claims are therefore intended to be embraced therein.

Claims

A liquid crystal display device comprising:

a main body (1) composed of a liquid crystal display means (34) possessing a plurality of signal electrodes (8) and a plurality of scanning electrodes (9) intersecting the signal electrodes (8), and driving means (13) for driving the liquid crystal display means (34) so as to form either a first image (14a) or a second display image (14b) on the liquid crystal display means (34) on the basis of a video signal; characterised in that the second image is the first image (14a) rotated about a point (0) in the first image (14a) by 180 degrees;

and in that the display device further comprises: positioning means (2) for selectively fixing the main body (1) either in a first position where a viewing angle for observing the image displayed on the liquid crystal display means (34) from a predetermined observation point P_a is included in an observable viewing angle region determined by a liquid crystal orientation of the liquid crystal display means (34) in a predetermined first posture or in a second position where the viewing angle for observing the display image from the observation point P_a is included in the observable viewing angle region of the liquid crystal display means in a second posture, the second posture being obtained by rotating the liquid crystal display means in the first posture by about 180 degrees about a normal to the display surface of the liquid crystal display means in the first posture; and

posture holding means (25) for selectively holding the main body (1) in either the first posture or the second posture, the posture holding means being supported by the positioning means (2).
A liquid crystal display device as claimed in claim 1, wherein the driving means (13) comprises a signal electrode drive circuit (32) for scanning a plurality of signal electrodes (S). a scanning electrode drive circuit (33) for scanning a plurality of scanning electrodes (G), and an inversion control circuit (35) for inverting the scanning directions of the signal electrode drive circuit (32) and scanning electrode drive circuit (33).
A liquid crystal display device as claimed in claim 1, wherein the positioning means (2) comprises:

a bar-shaped post member (16a, 16b),

support means for supporting the post member (16a, 16b) in a vertical direction on a plane of installation such as a floor or a ceiling, the support means being disposed at a first end of the post member (16a, 16b), and

connecting means for connecting the second end of the post member (16a, 16b) to the main body (1).
A liquid crystal display device as claimed in claim 3, wherein the connecting means comprises :

a dovetail tenon (18a, 18b) disposed on one of the second end of the post member (16a, 16b) or the main body, and

a connection member possessing a complementary dovetail groove (17a, 17b) for receiving the dovetail tenon (18a, 18b), the connection member being disposed on the other of the second end of the post member or the main body.
A liquid crystal display device as claimed in claim 3, wherein the connecting means is composed of a threaded hole formed in one of the second end of the post member (16a, 16b) or the main body (1), and a bolt to be screwed, in use, into the threaded hole is provided at the other of the second end of the post member (16a, 16b) or the main body (1).
A liquid crystal display device as claimed in claim 4, wherein a protrusion (59) is formed on one of the dovetail tenon (18a, 18b) or the connection member (15a, 15b), and a recess (60) in which the protrusion (59) is fitted, in use, is formed in the other of the dovetail tenon (18a, 18b) or the connection member (15a, 15b).
A liquid crystal display device as claimed in claim 3, wherein the connecting means functions as the posture holding means (25) by connecting a side of the main body (1) with the second end of the post member (16a, 16b) such that the side is either on an upper side of an image displayed on the liquid crystal display means (34) or on a lower side of the image.
A liquid crystal display device as claimed in claim 3, wherein the connecting means functions as the posture holding means (26) by selectively connecting a side of the main body (1) with the other end of the post member (16a, 16b) such that the side is either on a left side of an image displayed on the liquid crystal display means (34) or is on a right side of the image.
A liquid crystal display device as claimed in claim 3, wherein the positioning means comprises two post members (16a, 16b) differing in length.
A liquid crystal display device as claimed in claim 3, wherein the post member is expandable in length.
A liquid crystal display device as claimed in claim 3, wherein the positioning means (2) comprises:

a guide member (19), including first and second guide posts (20a, 20b) disposed parallel to each other, wherein the first and second guide grooves (21a, 21b) are formed in mutually confronting surfaces of the respective guide posts (20a, 20b); and

a slide plate (22) having an engagement piece (23a, 23b) to be engaged slidably with the guide grooves (21a, 21b), the slide plate being disposed on the back side of the main body (1);

wherein the guide member (19) comprises position holding means (24a, 24b) disposed on the guide posts (20a, 20b), for holding the engagement pieces and fixing the main body in the first or second position.
A liquid crystal display device as claimed in claim 11, wherein the posture holding means (25) comprises:

a circular protruding portion (26) formed on the back side of the main body (1); and

a hole (27) formed in the slide plate (22), the circular protruding portion (26) being fitted, in use in the hole;

wherein one of the circular protruding portion (26) and the slide plate (22) is provided with a detent protrusion (28) and an operating part (29) for projecting and retracting the detent protrusion (28), and wherein detent holes (30a, 30b) in which the detent protrusion fits, in use, are formed at two positions differing in phase by 180 degrees from each other in the other of the circular protruding portion (26) or the slide plate (22).