Input device and display apparatus including the same

1. Field of the Invention

The present invention relates to, for example, an input device that detects a location where the user has performed an input operation as an input position, and a display apparatus that includes the input device.

2. Description of the Related Art

An example of the input device is a capacitive touch panel that detects an input position on the basis of a change in capacitance between a finger and a detecting electrode (see, e.g., Japanese Unexamined Patent Application Publication No. 2008-97283).

Such an input device includes a substrate, a plurality of first detecting electrodes arranged on the substrate at predetermined intervals in a first direction, a plurality of second detecting electrodes arranged on the substrate at predetermined intervals in a second direction, at least one first connecting electrode configured to connect adjacent first detecting electrodes to each other, and at least one second connecting electrode configured to connect adjacent second detecting electrodes to each other. In this input device, to electrically isolate the first connecting electrode from the second connecting electrode, an insulator is provided at an intersection between the first connecting electrode and the second connecting electrode. Specifically, the insulator is formed such that it covers the first connecting electrode, and the second connecting electrode is formed on the insulator. Thus, at the intersection between the first connecting electrode and the second connecting electrode, the first connecting electrode is electrically isolated from the second connecting electrode.

However, in the input device described above, since the insulator is disposed at the intersection between the first connecting electrode and the second connecting electrode, the intersection and other portions differ in height. As a result, if the input device described above is included in a display apparatus, the intersection of the input device may be seen by the user.

The present invention has been made in view of the problem described above. An object of the present invention relates to an input device that can provide improved visibility and a display apparatus that includes the input device.

An input device according to an aspect of the present invention includes a substrate including a first principal surface and a second principal surface opposite the first principal surface; a plurality of first detecting electrodes disposed on the second principal surface of the substrate; a plurality of second detecting electrodes disposed on the second principal surface of the substrate; at least one first connecting electrode disposed on the second principal surface of the substrate, the first connecting electrode being configured to connect adjacent first detecting electrodes to each other; at least one second connecting electrode including an intersection that is spaced from the second principal surface of the substrate and crosses the first connecting electrode, the second connecting electrode being configured to connect adjacent second detecting electrodes to each other; and a light diffusing member disposed at least in an area corresponding to the intersection.

FIG. 1 is a plan view illustrating a general configuration of an input device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1 .

FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1 .

FIG. 4 illustrates diffusion of light through a light diffusing member.

FIG. 5 is a table showing a result of a subject test in which the haze value of the light diffusing member was set to any value from 0% to 10%.

FIG. 6 is a cross-sectional view illustrating a display apparatus according to an embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a general configuration of an input device according to a first modification. Note that FIG. 7 illustrates a cross section equivalent to that of FIG. 2 .

FIG. 8 is a cross-sectional view illustrating a general configuration of the input device according to the first modification. Note that FIG. 8 illustrates a cross section equivalent to that of FIG. 3 .

FIG. 9 is a cross-sectional view illustrating a general configuration of an input device according to a second modification. Note that FIG. 9 illustrates a cross section equivalent to that of FIG. 2 .

FIG. 10 is a cross-sectional view illustrating a general configuration of the input device according to the second modification. Note that FIG. 10 illustrates a cross section equivalent to that of FIG. 3 .

FIG. 11 is a cross-sectional view illustrating a general configuration of an input device according to a third modification. Note that FIG. 11 illustrates a cross section equivalent to that of FIG. 2 .

FIG. 12 is a cross-sectional view illustrating a general configuration of the input device according to the third modification. Note that FIG. 12 illustrates a cross section equivalent to that of FIG. 3 .

Embodiments of the present invention will now be described with reference to the drawings.

As illustrated in FIG. 1 to FIG. 3 , an input device X 1 of the present embodiment is a capacitive touch panel that includes a substrate 2 having translucency.

As illustrated in FIG. 1 , the input device X 1 has an input region E I and an outside region E O located outside the input region E I . The user can input information by moving a finger F 1 (see FIG. 2 and FIG. 3 ) closer to the input region E I or by touching or pressing the input region E I with the finger F 1 . The outside region E O includes an external conduction area G 1 electrically connected, for example, to a flexible printed circuit (FPC) (outside the drawing).

In the input region E I , the substrate 2 supports first detecting electrodes 3 a , first connecting electrodes 3 b , second detecting electrodes 4 a , and second connecting electrodes 4 b (described below). At the same time, the substrate 2 supports wiring conductors 6 (described below) in the outside region E O . The substrate 2 has a first principal surface 2 a and a second principal surface 2 b opposite the first principal surface 2 a . A portion of the first principal surface 2 a of the substrate 2 , the portion corresponding to the input region E I , is a surface which allows the user to input information by moving the finger F 1 closer thereto, or by touching or pressing it with the finger F 1 . Therefore, the first principal surface 2 a of the substrate 2 is preferably covered with a protective film (not shown). The substrate 2 is an insulating member capable of properly transmitting light therethrough in a direction crossing the principal surfaces 2 a and 2 b (i.e., in the direction of arrow EF). For example, the substrate 2 is made of material having translucency, such as transparent glass or transparent plastic. In particular, it is preferable that transparent glass be used, in terms of visibility and reliability. In the present specification, the term translucency refers to transmissive properties that allow visible light to pass through. The substrate 2 of the present embodiment is substantially rectangular in plan view, but the shape of the substrate 2 is not limited to this.

Referring to FIG. 2 and FIG. 3 , the first detecting electrodes 3 a , the first connecting electrode 3 b , the second detecting electrodes 4 a , the second connecting electrode 4 b , and an insulator 5 are disposed in a portion of the second principal surface 2 b of the substrate 2 , the portion corresponding to the input region E I .

The first detecting electrodes 3 a detect an input position of the finger F 1 near the input device X 1 in a second direction (i.e., in the direction of arrow CD). Capacitance is formed between the finger F 1 and the first detecting electrodes 3 a . The first detecting electrodes 3 a are arranged on the second principal surface 2 b of the substrate 2 at predetermined intervals in a first direction (i.e., in the direction of arrow AB). For better detection sensitivity, the first detecting electrodes 3 a of the present embodiment are substantially diamond-shaped in plan view. However, the shape of the first detecting electrodes 3 a is not limited to this.

As illustrated in FIG. 3 , the first connecting electrode 3 b connects the adjacent first detecting electrodes 3 a to each other. The first connecting electrode 3 b is disposed on the second principal surface 2 b of the substrate 2 .

The second detecting electrodes 4 a detect an input position of the finger F 1 near the input device X 1 in the first direction. Capacitance is formed between the finger F 1 and the second detecting electrodes 4 a . The second detecting electrodes 4 a are arranged on the second principal surface 2 b of the substrate 2 at predetermined intervals in the second direction. For better detection sensitivity, the second detecting electrodes 4 a of the present embodiment are substantially diamond-shaped in plan view. However, the shape of the second detecting electrodes 4 a is not limited to this.

As illustrated in FIG. 2 , the second connecting electrode 4 b connects the adjacent second detecting electrodes 4 a to each other. The second connecting electrode 4 b has an intersection H 1 that is spaced from the second principal surface 2 b of the substrate 2 and crosses the first connecting electrode 3 b . The second connecting electrode 4 b is disposed on the insulator 5 such that it is electrically isolated from the first connecting electrode 3 b . The insulator 5 is disposed on the second principal surface 2 b of the substrate 2 such that it covers the first connecting electrode 3 b . This means that in the input device X 1 , the intersection H 1 and other portions (e.g., the first detecting electrodes 3 a and the second detecting electrodes 4 a ) differ in height. The insulator 5 is made of, for example, transparent resin, such as acrylic resin, epoxy resin, or silicon resin.

The first detecting electrodes 3 a , the first connecting electrodes 3 b , the second detecting electrodes 4 a , and the second connecting electrodes 4 b are made of, for example, conductive material having translucency, such as indium tin oxide (ITO), indium zinc oxide (IZO), antimony tin oxide (ATO), al-doped zinc oxide (AZO), tin oxide, zinc oxide, or conductive polymer (e.g., polyethylene dioxythiophene (PEDOT) or polystyrene sulfonate (PSS)).

Referring to FIG. 1 , the wiring conductors 6 for applying voltage to the first detecting electrodes 3 a and the second detecting electrodes 4 a are disposed in a portion of the second principal surface 2 b of the substrate 2 , the portion corresponding to the outside region E o .

The wiring conductors 6 are electrically connected to the first detecting electrodes 3 a and the second detecting electrodes 4 a at one end, and located in the external conduction area G 1 at the other end. For higher hardness and shape stability, the wiring conductors 6 of the present embodiment are formed of a metal thin film. Examples of the metal thin film include an aluminum film, an aluminum alloy film, a laminated film composed of chromium and aluminum films, a laminated film composed of chromium and aluminum alloy films, a silver film, a silver alloy film, and a gold alloy film. Examples of a method for forming the metal thin film include sputtering, evaporation, and chemical-vapor deposition (CVD).

Referring to FIG. 2 and FIG. 3 , on the second principal surface 2 b of the substrate 2 , a light diffusing member 7 is disposed at least in an area corresponding to the intersection H 1 . In the present embodiment, the light diffusing member 7 is disposed such that it covers the first detecting electrodes 3 a , the first connecting electrode 3 b , the second detecting electrodes 4 a , the second connecting electrode 4 b , the insulator 5 , and the wiring conductors 6 (see FIG. 1 ).

The light diffusing member 7 is for diffusing light. The light diffusing member 7 includes an adhesive member 7 a and a plurality of light diffusing particles 7 b contained in the adhesive member 7 a and having a refractive index different from that of the adhesive member 7 a . The adhesive member 7 a is, for example, an acrylic adhesive member, an epoxy adhesive member, or a silicon adhesive member. The light diffusing particles 7 b are made of, for example, silicon dioxide, aluminum oxide, titanium oxide, yttrium oxide, zirconium dioxide, or hollow silicon dioxide. As described above, the light diffusing particles 7 b have a refractive index different from that of the adhesive member 7 a . However, to suppress backscattering, it is preferable that the refractive index of the light diffusing particles 7 b be as close as possible to that of the adhesive member 7 a.

FIG. 4 illustrates diffusion of light through the light diffusing member 7 . Note that arrows in FIG. 4 are conceptual representations of light paths. As illustrated in FIG. 4 , light (external light) coming from outside and light (internal light) coming from a backlight 51 (described below) when the input device X 1 is used in a display apparatus Y 1 (described below) are diffused or scattered by the light diffusing particles 7 b . Therefore, in the input device X 1 , even if the intersection H 1 differs in height from other portions, the intersection H 1 is less likely to be seen by the user.

As described above, the light diffusing member 7 is capable of diffusing light. This light diffusing capability depends on optical properties of the light diffusing member 7 . An example of physical property values representing optical properties of the light diffusing member 7 is a haze value. A haze value is expressed as the ratio of diffuse transmitted light to all transmitted light when the light diffusing member 7 is illuminated. This means that the higher the haze value, the higher the diffusing capability of the light diffusing member 7 . When light is diffused by the light diffusing member 7 , the intersection H 1 is less likely to be seen by the user. However, if the haze value of the light diffusing member 7 is too high, an image blur may occur and low visibility may result. Therefore, to prevent such an image blur while reducing the possibility that the intersection H 1 may be seen by the user, it is necessary to set the haze value of the light diffusing member 7 to an appropriate value.

FIG. 5 is a table showing a result of a subject test in which the haze value of the light diffusing member 7 was set to any value from 0% to 10%. Specifically, the subject (or observer) first checked the appearance of the intersection H 1 . In the middle column of the table of FIG. 5 , “good” indicates that the intersection H 1 was not seen, “fair” indicates that the intersection H 1 was slightly seen, and “poor” indicates that the intersection H 1 was seen. Next, the subject checked the visibility of an image. In the right column of the table of FIG. 5 , “good” indicates that the image was clearly displayed, “fair” indicates that the image was slightly blurred, and “poor” indicates that the image was blurred. FIG. 5 shows that when the haze value of the light diffusing member 7 was in the 0.5% to 2.0% range, the intersection H 1 was not seen and the image was clearly displayed. Therefore, it is preferable that the haze value of the light diffusing member 7 be in the 0.5% to 2.0% range. If it is acceptable that the intersection H 1 is slightly seen, the haze value of the light diffusing member 7 may be in the 0.3% to 0.5% range. If it is acceptable that the image is slightly blurred, the haze value of the light diffusing member 7 may be in the 2.0% to 5.0% range.

Referring to FIG. 2 and FIG. 3 , a protecting member 8 is disposed under the light diffusing member 7 .

The protecting member 8 is, for example, a polyethylene terephthalate (PET) film or a resin film. The protecting member 8 has a so-called anti-scattering function. For example, if the substrate 2 is broken, the protecting member 8 prevents the fragments of the substrate 2 from scattering. Without the protecting member 8 , the light diffusing member 7 is exposed to air and the adhesive member 7 a may absorb moisture. The moisture absorbed into the adhesive member 7 a may reach the first detecting electrodes 3 a , the first connecting electrode 3 b , the second detecting electrodes 4 a , and the second connecting electrode 4 b and may cause them to corrode. When the protecting member 8 is disposed under the light diffusing member 7 , moisture is less likely to be absorbed into the adhesive member 7 a . Therefore, in the input device X 1 of the present embodiment, it is less likely that the electrodes 3 a , 3 b , 4 a , and 4 b will corrode.

Next, a principle of detection performed by the input device X 1 of the present embodiment will be described.

When the finger F 1 (which is a conductor) moves closer to, or touches or presses a portion of the first principal surface 2 a of the substrate 2 , the portion corresponding to the input region E I , the capacitance between the finger F 1 and the detecting electrodes 3 a and 4 a changes. A driver (not shown) included in the input device X 1 always detects changes in capacitance between the finger F 1 and the detecting electrodes 3 a and 4 a . When the driver detects a capacitance change exceeding a predetermined value, the driver determines a position at which the capacitance change has been detected as an input position. Thus, the input device X 1 can detect an input position. A method that the input device X 1 uses to detect an input position may either be a mutual capacitance method or a self capacitance method. Using the mutual capacitance method is more preferable in that it allows a plurality of input positions to be detected at the same time.

The input device X 1 described above can be used, for example, in a display apparatus. FIG. 6 is a cross-sectional view illustrating an example of the display apparatus Y 1 according to the present embodiment. As illustrated in FIG. 6 , the display apparatus Y 1 includes the input device X 1 and a liquid-crystal display device Z 1 disposed opposite the input device X 1 .

The liquid-crystal display device Z 1 includes a liquid-crystal display panel 50 , the backlight 51 , and a housing 52 .

The backlight 51 includes a light source 51 a and a light guide plate 51 b . The light source 51 a emits light toward the light guide plate 51 b . For example, the light source 51 a is a light-emitting diode (LED). Instead of the LED, the light source 51 a may be a cold cathode fluorescent lamp (CCFL), a halogen lamp, a xenon lamp, or electroluminescence (EL). The light guide plate 51 b guides light from the light source 51 a substantially uniformly throughout the undersurface of the liquid-crystal display panel 50 .

The housing 52 contains the liquid-crystal display panel 50 and the backlight 51 . The housing 52 has an upper housing 52 a and a lower housing 52 b . For example, the housing 52 is made of resin (e.g., polycarbonate) or metal (e.g., stainless (SUS) or aluminum).

The input device X 1 and the liquid-crystal display device Z 1 are bonded to each other, with a double-faced tape T 1 therebetween. Specifically, the input device X 1 and the liquid-crystal display device Z 1 are bonded with the double-faced tape T 1 such that the back surface of the protecting member 8 of the input device X 1 faces a principal surface of the liquid-crystal display panel 50 . A fixing member used to secure the input device X 1 to the liquid-crystal display device Z 1 is not limited to the double-faced tape T 1 . For example, the fixing member may be a bonding member made of thermoset resin or ultraviolet curable resin, or may be a fixing structure that structurally secures the input device X 1 to the liquid-crystal display device Z 1 .

With the input device X 1 described above, the user can input various types of information by pressing the input region E I of the input device X 1 while looking at the liquid-crystal display panel 50 of the liquid-crystal display device Z 1 through the input device X 1 . The input device X 1 may have a function of transmitting a realistic feel of push-button switching operation to the user who is entering various types of information. To realize this function, the substrate 2 of the input device X 1 has a piezoelectric element. Then, when a predetermined load associated with a pressing operation is detected, the input device X 1 causes the piezoelectric element to vibrate at a predetermined frequency, and thereby causes the substrate 2 to vibrate in response to vibration of the piezoelectric element. A realistic feel of push-button switching operation can thus be transmitted to the user.

The display apparatus Y 1 described above may be incorporated into various electronic appliances, such as mobile terminals including mobile phones and personal digital assistants (PDAs), electronic notebooks, personal computers, copiers, and gaming terminals.

As described above, the input device X 1 and the display apparatus Y 1 can provide improved visibility.

The foregoing embodiment of the present invention is merely an example and various modifications can be made. Some modifications will now be described.

First Modification

FIG. 7 and FIG. 8 are cross-sectional views illustrating a general configuration of an input device X 2 according to a first modification. FIG. 7 illustrates a cross section equivalent to that of FIG. 2 , and FIG. 8 illustrates a cross section equivalent to that of FIG. 3 . In FIG. 7 and FIG. 8 , components having the same functions as those of the components illustrated in FIG. 2 and FIG. 3 are given the same reference numerals and their detailed description will be omitted.

As illustrated in FIG. 7 and FIG. 8 , the input device X 2 of the first modification includes the light diffusing member 7 , as in the case of the input device X 1 . However, the input device X 2 of the first modification is different from the input device X 1 in that the light diffusing member 7 is disposed such that it covers the intersection H 1 and the insulator 5 , and in that the light diffusing member 7 is not provided in areas where the intersection H 1 and the insulator 5 are not present. In the input device X 2 , in areas where the intersection H 1 and the insulator 5 are not present, a joining member 9 is provided instead of the light diffusing member 7 . The joining member 9 is made of, for example, transparent resin, such as acrylic resin, epoxy resin, or silicon resin.

Even when the light diffusing member 7 is disposed such that it covers the intersection H 1 and the insulator 5 and the light diffusing member 7 is not provided in areas where the intersection H 1 and the insulator 5 are not present, the same effects as those described in the above embodiment can be achieved. In the input device X 2 , in areas where the intersection H 1 and the insulator 5 are not present, the joining member 9 is provided instead of the light diffusing member 7 . Therefore, even if the haze value of the light diffusing member 7 is increased, it is possible to suppress an image blur. This means that in the input device X 2 , the appearance of the intersection H 1 can be more effectively improved.

Second Modification

FIG. 9 and FIG. 10 are cross-sectional views illustrating a general configuration of an input device X 3 according to a second modification. FIG. 9 illustrates a cross section equivalent to that of FIG. 2 , and FIG. 10 illustrates a cross section equivalent to that of FIG. 3 . In FIG. 9 and FIG. 10 , components having the same functions as those of the components illustrated in FIG. 2 and FIG. 3 are given the same reference numerals and their detailed description will be omitted.

As illustrated in FIG. 9 and FIG. 10 , as in the case of the input device X 1 , the input device X 3 of the second modification includes the insulator 5 disposed on the second principal surface 2 b of the substrate 2 such that it covers the first connecting electrodes 3 b . However, the input device X 3 of the second modification is different from the input device X 1 in that the insulator 5 not only electrically isolates the first connecting electrodes 3 b from the second connecting electrodes 4 b , but also serves as a light diffusing member. The insulator (light diffusing member) 5 contains a plurality of light diffusing particles 5 a having a refractive index different from that of the insulator 5 .

In the input device X 3 of the second modification, the joining member 9 is disposed such that it covers the first detecting electrodes 3 a , the first connecting electrode 3 b , the second detecting electrodes 4 a , the second connecting electrode 4 b , the insulator 5 , and the wiring conductors 6 . The protecting member 8 is disposed on the joining member 9 .

Even when the insulator 5 serves as a light diffusing member, the same effects as those described in the above embodiment can be achieved. In the input device X 3 of the second modification, since the insulator 5 serves as a light diffusing member, an image blur can be suppressed even if the haze value of the insulator (light diffusing member) 5 is increased. This means that in the input device X 3 , the appearance of the intersection H 1 can be more effectively improved.

Third Modification

FIG. 11 and FIG. 12 are cross-sectional views illustrating a general configuration of an input device X 4 according to a third modification. FIG. 11 illustrates a cross section equivalent to that of FIG. 2 , and FIG. 12 illustrates a cross section equivalent to that of FIG. 3 . In FIG. 11 and FIG. 12 , components having the same functions as those of the components illustrated in FIG. 2 and FIG. 3 are given the same reference numerals and their detailed description will be omitted.

As illustrated in FIG. 11 and FIG. 12 , in the input device X 4 of the third modification, a protecting member 10 is disposed on the first principal surface 2 a of the substrate 2 . The protecting member 10 is, for example, a PET film or a resin film. The protecting member 10 not only protects the first principal surface 2 a of the substrate 2 , but also serves as a light diffusing member. The protecting member (light diffusing member) 10 contains a plurality of light diffusing particles 10 a having a refractive index different from that of the protecting member 10 .

Even when the protecting member 10 serves as a light diffusing member, the same effects as those described in the above embodiment can be achieved.

Fourth Modification

In the input device X 1 described above, a portion of the first principal surface 2 a of the substrate 2 , the portion corresponding to the input region E I , is a surface which allows the user to input information by moving the finger F 1 closer thereto, or by touching or pressing it with the finger F 1 . However, this is merely an example. That is, the back surface of the protecting member 8 may serve as a surface which allows the user to input information by moving the finger F 1 closer thereto, or by touching or pressing it with the finger F 1 . In this case, the input device X 1 and the liquid-crystal display device Z 1 are bonded to each other such that the first principal surface 2 a of the substrate 2 faces the principal surface of the liquid-crystal display panel 50 .

Fifth Modification

In the description above, the display panel to which the input device X 1 is bonded is a liquid-crystal display panel. However, the display panel is not limited to this. The display panel to which the input device X 1 is bonded may be, for example, a cathode-ray tube (CRT), a plasma display, an organic electroluminescent (EL) display, an inorganic EL display, an LED display, a fluorescent display tube, a field emission display, or a surface-conduction electron-emitter display.

Sixth Modification

Although the display apparatus Y 1 including the input device X 1 has been described above, the input device X 1 may be replaced by any of the input devices according to the first to fifth modifications.