Indication device

Abstract

To provide a display device capable of suppressing leakage of illumination light caused by a strain of a liquid crystal panel even when a transparent protective plate is pressed downward.SOLUTION: A display device 10 includes a sensor substrate (52), a liquid crystal panel 16 placed just above the sensor substrate (52) and having a display surface, a transparent protective plate 18 that supports the liquid crystal panel 16 from above by fixing the same through a display surface, and a casing 12 having a support frame 30 supporting the transparent protective plate 18 and storing the sensor substrate (52). The support frame 30 and the liquid crystal panel 16 are provided so as not to overlap with each other in plan view.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a display device including a sensor substrate.

Background Art

[0002] Conventionally, in the technical field of display devices, a direct-type backlight that forms a surface light source by arranging a light-emitting element array on the back side of a display panel is known (see, for example, Patent Documents 1 to 3). Hereinafter, the electronic circuit board on which the light-emitting element array is mounted may be referred to as a "light source substrate". [[ID=!13]]

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to provide a writing function to the above-described display device, a position detection sensor may be incorporated on the back side of the display panel. As a method of this type of sensor, for example, an electromagnetic induction method (so-called EMR method) that detects an alternating magnetic field transmitted from a position indicator through a plurality of loop coils arranged one-dimensionally or two-dimensionally can be mentioned. Hereinafter, the electronic circuit board on which the position detection sensor is mounted may be referred to as a "sensor substrate".

[0005] Both the light source substrate and the sensor substrate described above are desirable to be positioned as close to the display panel as possible and parallel to it in order to perform their respective functions (i.e., light emission function or detection function). For this reason, a device configuration in which both substrates are arranged parallel to and facing each other may be adopted. However, with this arrangement, a problem arises in that electromagnetic interference is likely to occur between the line wiring mounted on the light source substrate and the coil wiring mounted on the sensor substrate. As a result, electromagnetic noise may be introduced into the coil wiring, potentially leading to a decrease in detection accuracy or malfunction of the sensor substrate.

[0006] The present invention has been made in view of these problems, and its objective is to provide a sensor substrate and a display device that can suppress the generation of electromagnetic noise due to electromagnetic interference between the wirings of the light source substrate and the sensor substrate, respectively. [Means for solving the problem]

[0007] The first sensor substrate of the present invention comprises a light-emitting array in which a plurality of light-emitting elements are arranged two-dimensionally, and a plurality of loop coils for detecting the position indicated by an electronic pen through electromagnetic induction generated between the electronic pen and the light-emitting array, wherein the line wiring connected to the light-emitting array is partially shared with the coil wiring formed by the plurality of loop coils.

[0008] The second display device of the present invention comprises a light source substrate on which a plurality of light-emitting elements are arranged two-dimensionally, and a sensor substrate on which a plurality of loop coils are formed that extend in a first direction and / or a second direction intersecting the first direction, and which detects a two-dimensional position indicated by the electronic pen through electromagnetic induction generated between the plurality of loop coils and the electronic pen, wherein the light source substrate and the sensor substrate are arranged opposite each other while maintaining a parallel relationship, and on the light source substrate, line wiring connected to each of the light-emitting elements is routed along a third direction that is inclined with respect to both the first direction and the second direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress the generation of electromagnetic noise caused by electromagnetic interference between the wirings of the light source substrate and the sensor substrate, respectively. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a display device common to each embodiment of the present invention. [Figure 2] This is an exploded perspective view showing the main parts of the display device in the first embodiment. [Figure 3] This figure shows an example of the circuit configuration of the sensor board shown in Figure 2. [Figure 4] This figure shows an example of the wiring structure of the light source substrate shown in Figure 2. [Figure 5] This figure shows the effects of the wiring structure shown in Figure 4. [Figure 6] This is a circuit diagram of the sensor board in a modified example of the first embodiment. [Figure 7] This is an exploded perspective view showing the main parts of the display device in the second embodiment. [Figure 8] Figure 1 shows a portion of the wiring configuration of the light source sensor board shown in Figure 7. [Figure 9] Figure 2 shows a portion of the wiring configuration of the light source sensor board shown in Figure 7. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the attached drawings. To facilitate understanding of the description, the same reference numerals are used for identical components in each drawing whenever possible, and redundant explanations are omitted.

[0012] [Overall structure] FIG. 1 is a cross-sectional view of a display device 10 common to each embodiment of the present invention. Here, it is assumed that the display device 10 is assembled using a semi-finished product called a so-called "open cell" without a backlight module. Specifically, the display device 10 includes a casing 12, a substrate group 14, a liquid crystal panel 16, and a transparent protection plate 18. The casing 12 is configured by combining a low-profile rectangular parallelepiped back cover 20 and a support frame 30 having a substantially H-shaped cross-section.

[0013] The back cover 20 has an opening upward and houses the substrate group 14 in a state of surface contact with the bottom portion 22. The support frame 30 includes a frame portion 32 in the shape of a frame, a first protruding portion 34 protruding downward from the outside of the frame portion 32, and a second protruding portion 36 protruding downward from the inside of the frame portion 32. The first protruding portion 34 is configured to be engageable with the side portion 24 of the back cover 20. The second protruding portion 36 is configured to be able to fix the substrate group 14 by pressing the substrate group 14 from above.

[0014] The substrate group 14 is formed by laminating at least a plurality of substrates that exhibit a light-emitting function and a pen detection function. The light-emitting function is a function of emitting illumination light (so-called backlight) from the back surface to the front surface of the liquid crystal panel 16. The pen detection function is a function of detecting a position indicated by an electromagnetic induction (EMR) type electronic pen.

[0015] The transparent protection plate 18 is a plate-like member with a high light transmittance for protecting the display surface of the liquid crystal panel 16, and is composed of, for example, glass. The liquid crystal panel 16 is adhered to the back surface of the transparent protection plate 18 via an optical adhesive layer 40. That is, the transparent protection plate 18 supports the liquid crystal panel 16 from above by being fixed through the display surface. Note that, as the material of the optical adhesive layer 40, for example, an optical clear adhesive sheet (OCA: Optical Clear Adhesive) or an optical clear resin (OCR; Optical Clear Resin) is used.

[0016] Further, a plurality of convex portions 42 are formed on the back surface of the transparent protection plate 18 at positions outside the fixed portion of the liquid crystal panel 16. The support frame 30 fixes and supports the transparent protection plate 18 in a state where the concave portion 38 and the convex portion 42 are engaged. In this case, the support frame 30 and the liquid crystal panel 16 are in a positional relationship where they do not overlap in plan view. Hereinafter, the reason for this will be explained.

[0017] For example, a structure in which the support frame 30 projects vertically inward from the second projecting portion 36 and partially supports the liquid crystal panel 16 from below may also be adopted. However, when the user presses the transparent protection plate 18 downward during use of the display device 10, the non-display surface of the liquid crystal panel 16 may contact the support frame 30, and the peripheral portion of the liquid crystal panel 16 may be distorted. As a result, the light shielding function by the liquid crystal may not be partially exerted, and the illumination light emitted from the substrate group 14 may leak through the peripheral portion of the liquid crystal panel 16. As a result, the display quality of the display device 10 deteriorates.

[0018] Therefore, the display device 10 in FIG. 1 includes a substrate group 14, a liquid crystal panel 16 disposed directly above the substrate group 14 and having a display surface, a transparent protection plate 18 that supports the liquid crystal panel 16 from above by being fixed through the display surface, a support frame 30 that supports the transparent protection plate 18, and a casing 12 that houses the substrate group 14. The support frame 30 and the liquid crystal panel 16 are provided so as not to overlap in plan view.

[0019] By configuring in this way, even when the transparent protection plate 18 is pressed downward, it is possible to avoid the non-display surface of the liquid crystal panel 16 interfering with the support frame 30, and it is possible to suppress the leakage of illumination light due to the distortion of the liquid crystal panel 16.

[0020] [First Embodiment] Subsequently, the substrate group 14A incorporated in the display device 10 in the first embodiment will be described while referring to FIGS. 2 to 5.

[0021] [Configuration] Figure 2 is an exploded perspective view showing the main parts of the display device 10 in the first embodiment. More specifically, this figure schematically shows the stacking relationship between the substrate group 14A and the liquid crystal panel 16 in the first embodiment. This substrate group 14A is constructed by stacking a light source substrate 50, a sensor substrate 52, and a drive substrate 54 in order of proximity to the liquid crystal panel 16. The drive substrate 54 is connected to the light source substrate 50 via a flexible printed circuit board (hereinafter referred to as FPC 56) and controls the driving of the LED array 84 (see Figure 4), which will be described later.

[0022] Figure 3 shows an example of the circuit configuration of the sensor board 52 shown in Figure 2. The sensor board 52 detects the two-dimensional position indicated by the electronic pen through electromagnetic induction generated between the loop coils 70, 72 and the electronic pen. Specifically, various electronic components, including a sensor unit 60, a selection circuit 62, a switch 64, a transmitting amplifier 66, and a receiving amplifier 68, are provided on the front or back of the sensor board 52.

[0023] The sensor unit 60 is composed of a first loop coil group 70G and a second loop coil group 72G. The first loop coil group 70G and the second loop coil group 72G are arranged to intersect each other to form a two-dimensional grid. This forms a rectangular detection area 74 for indicating a two-dimensional position on the XY coordinate system.

[0024] The first loop coil group 70G is an assembly of coil wiring consisting of N (N≧2) loop coils 70 arranged in a line in the X direction and extending in the Y direction. Each loop coil 70 has a long rectangular shape with a substantially constant width regardless of its position in the Y direction. Each loop coil 70 is connected to the selection circuit 62 at one end and to a reference potential (for example, ground potential) at the other end.

[0025] The second loop coil group 72G is an assembly of coil wiring consisting of M (M≧2) loop coils 72 arranged in a row in the Y direction and extending in the X direction. Each loop coil 72, like the loop coil 70, has a long rectangular shape with a substantially constant width regardless of its position in the X direction. Each loop coil 72 is connected to the selection circuit 62 at one end and to a reference potential (for example, ground potential) at the other end.

[0026] The selection circuit 62 switches the connection destination between the sensor units 60 in response to a control signal from a controller (not shown). As a result, one loop coil 70 from the first loop coil group 70G is selectively connected to the switch 64. Alternatively, one loop coil 72 from the second loop coil group 72G is selectively connected to the switch 64.

[0027] Switch 64 switches the connection destination to either the T terminal or the R terminal in response to a control signal from a controller (not shown). For example, when the connection destination is the T terminal, switch 64 outputs the transmission signal supplied from the transmission amplifier 66 to the sensor unit 60. On the other hand, when the connection destination is the R terminal, switch 64 outputs the reception signal supplied from the sensor unit 60 to the receiving amplifier 68.

[0028] Figure 4 shows an example of the wiring structure of the light source substrate 50 shown in Figure 2. An LED array 84, which is a collection of light-emitting diodes (hereinafter referred to as LEDs 82), is provided on the main surface 80 of this light source substrate 50. The LED array 84 has multiple LEDs 82 arranged in a grid pattern with the X and Y directions as two axes. Line wiring is provided on the anode and cathode sides of each LED 82, which is routed to the FPC 56 or FPC 58. For the sake of illustration, only the cathode wire is shown here.

[0029] Multiple line wirings 86 extend in the D direction, which is inclined with respect to both the X and Y directions, and are arranged at approximately equal intervals. At least one LED 82 in its vicinity is connected to one line wiring 86. For example, five LEDs are connected to the line wiring 86 indicated by reference numerals. The inclination angle with respect to the X direction is preferably in the range of 15 to 75 degrees, and more preferably in the range of 30 to 60 degrees.

[0030] <Effects and Effects> The substrate group 14A in the first embodiment is configured as described above. Next, the effects of the wiring structure in Figure 4 will be explained with reference to Figure 5. The left side of Figure 5 shows a "comparative example," and the right side of Figure 5 shows an "example."

[0031] In the "Comparative Example" in Figure 5, we assume that the line wiring 88Y is provided parallel to the Y direction along the arrangement direction of the LED array 84. Under the positional relationship in which the light source substrate 50 and the sensor substrate 52 are arranged opposite each other while maintaining a parallel relationship, electromagnetic interference may occur between the loop coil 70 and the line wiring 88Y. In particular, as the parallel wiring section becomes longer, spatial conduction of electromagnetic noise becomes more likely through stray capacitance and magnetic coupling. As a result, electromagnetic noise may be mixed into the loop coil 70, which may lead to a decrease in detection accuracy or malfunction of the sensor substrate 52.

[0032] On the other hand, in the "Embodiment" shown in Figure 5, the line wiring 88 extends at an inclination in both the X and Y directions. In this case, even when the light source substrate 50 and the sensor substrate 52 are arranged parallel to and opposite each other, the loop coil 70 and the line wiring 86 are in a "twisted position". As a result, electromagnetic noise is less likely to be introduced into the loop coil 70 through the cancellation effect of electromagnetic waves generated between the loop coil 70 and the line wiring 88Y. Consequently, a decrease in detection accuracy and malfunction of the sensor substrate 52 are suppressed.

[0033] As described above, the display device 10 in the first embodiment comprises a light source substrate 50 on which a plurality of LEDs 82 (light-emitting elements) are arranged two-dimensionally, and a sensor substrate 52 that detects a two-dimensional position indicated by an electronic pen through electromagnetic induction generated between a plurality of loop coils 70, 72 arranged extending in the X direction (first direction) and / or the Y direction (second direction) intersecting the X direction and an electronic pen. The light source substrate 50 and the sensor substrate 52 are arranged opposite each other while maintaining a parallel relationship, and on the light source substrate 50, line wiring 86 connected to each of the LEDs 82 is routed along the D direction (third direction) which is inclined with respect to both the X direction and the Y direction.

[0034] This configuration prevents the line wiring 86 and loop coils 70 and 72 from being substantially parallel, even when the light source substrate 50 and the sensor substrate 52 are arranged opposite each other while maintaining a parallel relationship. This suppresses the generation of electromagnetic noise due to electromagnetic interference between the wirings of the light source substrate 50 and the sensor substrate 52.

[0035] Furthermore, the multiple loop coils include a first loop coil group 70G arranged side by side in the X direction and extending in the Y direction, and a second loop coil group 72G arranged side by side in the Y direction and extending in the X direction, and the first loop coil group 70G and the second loop coil group 72G may be arranged to intersect each other and form a two-dimensional grid. This makes it possible to simultaneously prevent [1] the line wiring 86 and the loop coil 70 from being parallel, and [2] the line wiring 86 and the loop coil 72 from being parallel.

[0036] <Variation> Figure 6 is a circuit diagram of the sensor board 52A in a modified example of the first embodiment. Various electronic components, including a sensor unit 90, a selection circuit 62, a switch 64, a transmitting amplifier 66, and a receiving amplifier 68, are provided on the front or back of the sensor board 52A. In other words, the wiring structure of the sensor unit 60 (Figure 3) of the sensor board 52A is different from that of the sensor board 52 in the first embodiment. This sensor unit 90 is composed of a first loop coil group 92G and a second loop coil group 94G. This forms a rectangular detection area 96 for indicating a two-dimensional position on the XY coordinate system.

[0037] The first loop coil group 92G is an assembly of coil wiring consisting of N × M / 2 loop coils 92 (N, M ≥ 2) arranged in a line in the X direction and extending in the Y direction. Each loop coil 92 has a square-shaped bulging tip. Each loop coil 92 is connected to the selection circuit 62 at one end and to a reference potential (for example, ground potential) at the other end.

[0038] The second loop coil group 94G is an assembly of coil wiring consisting of N × M / 2 loop coils 94 arranged side by side in the Y direction and extending in the X direction. Each loop coil 94, like the loop coil 92, has a square-shaped bulging tip. Each loop coil 94 is connected to the selection circuit 62 at one end and to a reference potential (for example, ground potential) at the other end.

[0039] The first loop coil group 92G and the second loop coil group 94G are arranged so that M × N tip portions form a two-dimensional grid. In the example shown in this figure, the first loop coil group 92G and the second loop coil group 94G are arranged complementaryly so as to form a checkerboard pattern. The relationship between the loop coils 92 and 94 (position, arrangement, number, etc.) is not limited to this. For example, the sensor unit 90 can be constructed using only the first loop coil group 92G or only the second loop coil group 94G.

[0040] Thus, the multiple loop coils 92 and 94 may have block-shaped protruding tips, and the tips may be arranged to form a two-dimensional grid. This configuration also prevents, as in the first embodiment, from [1] the line wiring 86 (Figure 4) and the loop coil 92 being parallel, and [2] the line wiring 86 and the loop coil 94 being parallel.

[0041] [Second Embodiment] Next, the group of substrates 14B incorporated into the display device 10 in the second embodiment will be described with reference to Figures 7 to 9.

[0042] <Structure> Figure 7 is an exploded perspective view showing the main parts of the display device 10 in the second embodiment. More specifically, this figure schematically shows the stacking relationship between the substrate group 14B and the liquid crystal panel 16 in the second embodiment. This substrate group 14B is constructed by stacking a light source sensor substrate 100 and a drive substrate 54 in order of proximity to the liquid crystal panel 16. The drive substrate 54 is connected to the light source sensor substrate 100 via an FPC 56 and controls the driving of the LED array 106 (see Figure 8), which will be described later.

[0043] Figure 8 is the first figure showing an example of the wiring structure of the light-emitting sensor substrate 100 shown in Figure 7. This figure mainly extracts and shows the essential parts of the wiring structure related to the light-emitting function. An LED array 106, which is a collection of light-emitting diodes (hereinafter referred to as LEDs 104), is provided on the main surface 102 of this light-emitting sensor substrate 100. The LED array 106 has multiple LEDs 104 arranged in a grid pattern with the X and Y directions as two axes. An individual line wiring 108 is connected to the anode side of each LED 104. On the other hand, a common line wiring 110 is connected to the cathode side of each LED 104.

[0044] Figure 9 is the second figure showing an example of the wiring structure of the light-emitting sensor board 100 shown in Figure 7. This figure mainly extracts and shows the essential parts of the wiring structure related to the detection function. The light-emitting sensor board 100 detects the two-dimensional position indicated by the electronic pen through electromagnetic induction that occurs between the loop coil 120 and the electronic pen. Specifically, the light-emitting sensor board 100 is composed of a first loop coil group 120G and a selection circuit 122 having the same function as the first embodiment (selection circuit 62 in Figure 3). Although not shown, the light-emitting sensor board 100 is provided with various electronic components, including switches, a transmitting amplifier, and a receiving amplifier, similar to the configuration of the first embodiment (Figure 3).

[0045] The first loop coil group 120G is an assembly of coil wiring consisting of N (N≧2) loop coils 120 arranged in a line in the X direction and extending in the Y direction. Each loop coil 120 has a long rectangular shape with a substantially constant width regardless of its position in the Y direction. Each loop coil 120 is connected to the selection circuit 122 at one end and to the ground wire 124 at the other end.

[0046] The anode side of LED104 is connected to the drive board 54 (Figure 7) via line wiring 108. On the other hand, the cathode side of LED104 is connected to the ground line 124 via line wiring 110. Although only one LED104 (Figure 8) is shown here, other LED104s not shown are wired in the same way.

[0047] Note that although this figure only shows the first loop coil group 120G for detecting the indicated position in the X direction, a second loop coil group 72G for detecting the indicated position in the Y direction is also provided, as in the first embodiment (Figure 3). Alternatively, the wiring structure shown in Figure 6 can also be adopted.

[0048] <Effects and Effects> As described above, the light-emitting sensor board 100 comprises an LED array 106 (light-emitting element array) in which a plurality of LEDs 104 (light-emitting elements) are arranged two-dimensionally, and a plurality of loop coils 120 for detecting the position indicated by the electronic pen through electromagnetic induction generated between the electronic pen and the LED array 106. The line wiring connected to the LED array 106 is partially shared with the coil wiring formed by the plurality of loop coils 120. For example, the line wiring 110 connected to the cathode side of two or more LEDs 104 and one end of two or more loop coils 120 are connected to a common ground line 124.

[0049] In this way, the line wiring connected to the LED array 106 is partially shared with the coil wiring of the multiple loop coils 120, eliminating the need to consider the arrangement of the separately provided light source substrate and sensor substrate. This suppresses the generation of electromagnetic noise due to electromagnetic interference between the wiring of the light source substrate and sensor substrate. Furthermore, the integration of the circuit board reduces manufacturing costs and installation space.

[0050] [Differentiation] It should be noted that the present invention is not limited to the embodiments and modifications described above, and can be freely modified without departing from the spirit of the invention. Alternatively, the various components can be combined arbitrarily as long as no technical inconsistencies arise.

[0051] In the embodiments described above, the display device 10 in Figure 1 was described as having a "direct type" backlight, but the type of backlight is not limited to this. For example, the display device may incorporate an "edge-light type" backlight in which light-emitting elements are arranged on the side of the display surface.

[0052] In the first embodiment described above, a case in which a light-emitting diode (LED) is provided on the light source substrate 50 in Figure 3 was explained, but the light-emitting element is not limited to this. For example, the light-emitting element may be an organic LED (OLED) or a laser diode. The same applies to the light-emitting element in the second embodiment (Figure 8).

[0053] [Explanation of symbols] 10…Display device, 12…Casing, 14,14A,14B…Substrate group, 16…Liquid crystal panel, 18…Transparent protective plate, 30…Support frame, 50…Light source substrate, 52,52A,90…Sensor substrate, 70G,92G,120G…First loop coil group, 72G,94G…Second loop coil group, 82,104…LED (Light-emitting element), 100…Sensor substrate with light source (Sensor substrate)

Claims

1. A sensor board equipped with multiple loop coils for detecting the position indicated by an electronic pen through electromagnetic induction generated between electronic pens, A rear cover that opens upwards and houses the sensor substrate, A liquid crystal panel having a display surface is positioned directly above the aforementioned sensor substrate, A transparent protective plate that supports the liquid crystal panel from above by fixing it through the display surface, A support frame that supports the transparent protective plate and engages with the rear cover, Equipped with, The support frame has a frame-shaped part, a first projection that protrudes downward from the outside of the frame part, and a second projection that protrudes downward from the inside of the frame part. The first protrusion secures the rear cover by engaging with the side of the rear cover from the outside. The display device is provided such that the second protrusion does not overlap with the liquid crystal panel in a plan view and does not come into contact with the peripheral edge of the liquid crystal panel when the transparent protective plate is pressed downward.

2. The sensor substrate is positioned on the inner bottom surface of the rear cover such that it does not come into contact with the non-display surface of the liquid crystal panel opposite to the display surface when the transparent protective plate is pressed downward, The display device according to claim 1.

3. The tip of the second protrusion is provided so as to press the sensor substrate from above, The display device according to claim 2.

4. The sensor substrate further comprises a light-emitting array in which a plurality of light-emitting elements are arranged two-dimensionally. The display device according to claim 1.

5. The line wiring connected to the aforementioned light-emitting array is partially shared with the coil wiring formed by the multiple loop coils. The display device according to claim 4.

6. The line wiring connected to the cathode side of the light-emitting element and one end of the loop coil are connected to a common ground wire. The display device according to claim 5.

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