Optical touch panel and light guide module thereof

An optical touch panel includes a panel and a light guide module. The light guide module is disposed on the panel, and the light guide module includes a printed circuit board, at least one light emitting element, and a light guide strip. The light emitting element is electrically disposed on the printed circuit board. The light guide strip is disposed on the printed circuit board, and wraps the light emitting element. Additionally, the light emitting element emits light rays, and the light rays penetrate the light guide strip and are emitted to the panel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No. 100104651 filed in Taiwan, R.O.C. on Feb. 11, 2011, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical touch panel, and more particularly to an optical touch panel having a light guide module.

2. Related Art

In recent years, a previous input manner of pressing a mechanical button begins to be replaced with an input manner in which a screen is contacted with an object or a finger. When a user contacts an image on the screen, a tactile feedback system on the screen may convert detected light ray data into an electronic signal and transfer the electronic signal to a processor, and the processor drives various electronic devices with a pre-programmed program, and thus vivid video and audio effects are presented through a screen picture.

A conventional tactile feedback system comprises a glass substrate, a Light Emitting Diode (LED), a photo-sensitive element, a lens, a reflecting element, and a light guide element. The photo-sensitive element, the LED and the lens are configured at an upper right corner of the glass substrate, and the reflecting sheet and the light guide element are simultaneously disposed at left and lower devices of the glass substrate.

The optical touch principle is to illuminate a distal reflecting component by a light emitting device, and when the finger or the contact object shields light rays, the photo-sensitive element may convert sensed and collected light ray changes into an electronic signal, and transfer the electronic signal to the processor to calculate a relative position of the finger or the contact object on the glass substrate. In order to enable the processor to precisely calculate the position of the finger on the glass substrate, internal components of an optical touch screen all need to be aligned repetitively and precisely. However, the number of the internal components of the optical touch screen in the prior art is excessively large, so the optical touch screen in the prior art is confronted with a complicated alignment problem.

Furthermore, the conventional optical touch screen reflects the light rays emitted by the light emitting device with the reflecting element to detect the relative position of the finger or the contact object on the glass substrate, so when the photo-sensitive element is receiving the light rays reflected by the reflecting element, a signal output by the photo-sensitive element is easily influenced by a surrounding light source. Likewise, the light rays reflected by the reflecting component and the light rays emitted by the light emitting device generate interference on the photo-sensitive element, thereby influencing the precision of sensing the light rays by the photo-sensitive element. Additionally, the light emitting device placed at the upper right corner of the glass substrate must illuminate the distal reflecting element, so a light emitting element of the optical touch screen in the prior art needs large brightness output and current input.

SUMMARY OF THE INVENTION

Accordingly, the present invention is an optical touch panel and a light guide module thereof, thereby solving problems in the prior art that large brightness output and current output are needed and repetitive and precise alignment is required during assembling.

The optical touch panel according to the present invention comprises a panel, a sensing element, and a light guide module. The panel has a touch area, and the light guide module is disposed on the panel. Moreover, the light guide module comprises a printed circuit board, at least one light emitting element, and a light guide strip. The light emitting element is electrically disposed on the printed circuit board, and emits light rays. The light guide strip is disposed on the printed circuit board, and wraps the light emitting element. The light guide strip has a first surface and the light rays are emitted out from the first surface, and the first surface is a light transmissive surface. The sensing element is disposed on the panel and located out of the touch area, and the sensing element is used for sensing an image formed when the light rays are projected onto an object.

The light guide module according to the present invention comprises a printed circuit board, a plurality of light emitting elements, and light transmissive plastic. A contact surface of the printed circuit board is rectangular, and the light emitting elements are electrically disposed on the contact surface of the printed circuit board. The light emitting elements are disposed on the contact surface along a long side of the contact surface at a predetermined interval. Finally, the light transmissive plastic is molded on the contact surface of the printed circuit board in a manner of extrusion molding or injection molding, and covers the light emitting elements.

In the optical touch panel according to the present invention, the light emitting element and the printed circuit board are integrated in a manner of extrusion molding or injection molding with the light transmissive plastic, so when the optical touch panel is assembled, it is only necessary to combine the light guide module with the printed circuit board, thereby replacing a method in which a light emitting device and a lens need to be assembled through an alignment reflecting element and a light guide element in the prior art. Therefore, compared with the prior art, the optical touch panel according to the present invention is capable of omitting a complicated alignment process, thereby saving assembling time of the optical touch panel.

In the optical touch panel according to the present invention, light rays are emitted out with a plurality of light emitting elements, and a uniform effect is generated, so as to solve a problem in the prior art that light rays generated by a light emitting device through a lens, a reflecting element and a light guide element are interfered with each other. Therefore, the optical touch panel according to the present invention is capable of reducing brightness needed by the light emitting element, thereby reducing brightness output and current input of the light emitting element.

DETAILED DESCRIPTION OF THE INVENTION

In an optical touch panel and a light guide module thereof according to the present invention, the mentioned light emitting element is a component mounted in the optical touch panel, the mentioned light emitting element comprises, but not limited to, a direct-light LED, a side-light LED, or a Cold Cathode Fluorescence Lamp (CCFL), but in the following specific embodiment of the present invention, the direct-light LED is used as an embodiment of the present invention.

FIG. 1is a schematic three-dimensional view of a first embodiment according to the present invention,FIG. 1Bis a schematic enlarged view of a light guide module inFIG. 1A, andFIG. 1Cis a schematic plane view of the light guide module inFIG. 1A.

Referring toFIG. 1A, the optical touch panel according to the present invention comprises a panel100, a sensing element300, and a light guide module200. The panel100is a transparent flat panel of an optical touch screen, and has a touch area110. The light guide module200is disposed at a side edge of the panel100and located out of the touch area110, and emits light rays to the touch area110. The sensing element300is disposed on the panel100and located at a corner out of the touch area110, and the sensing element300is used for sensing an image formed when the light rays are projected onto an object.

In this embodiment, the sensing element300is disposed at a corner out of the touch area110, but the present invention is not limited to this, and for design needs, persons skilled in the art may further dispose the sensing element300at any position out of the touch area110, such as at a side edge or a bottom edge.

The light guide module200is illustrated in detail hereinafter. Simultaneously referring toFIGS. 1A to 1C, the light guide module200according to the present invention comprises a printed circuit board210, a light emitting element220, and a light guide strip230. For example, the printed circuit board210is in a strip shape, and the light emitting element220is an LED.

FIG. 2Ais a schematic three-dimensional view showing a light ray emission direction of a direct-light LED, andFIG. 2Bis a schematic three-dimensional view of the direct-light LED inFIG. 2Awith a metal contact added. Continuously referring toFIGS. 2A and 2B, the light emitting element220protrudes on the printed circuit board210, the light emitting element220has a top surface223and a first lateral surface222, and the light emitting element220is electrically disposed on the printed circuit board210through a metal contact221of the top surface223, so as to enable the light emitting element220to obtain supplies of a power supply through the printed circuit board210. The light emitting element220is a direct-light LED400, a majority of the light rays thereof is mainly emitted out from the top surface223, and a part of the light rays is emitted from a lateral surface, so in order to enable light rays to be emitted out from a main light exit surface (the first lateral surface222), in this embodiment, the area of the metal contact221is enlarged, so as to mask light rays emitted by the light emitting element220from the top surface223.

Referring toFIG. 3,FIG. 3is a schematic three-dimensional view showing a light ray emission direction of a side-light LED. In order to more effectively utilize the light source of the LED, in other embodiments according to the present invention, the LED may be changed into a side-light LED410, and a light ray emission direction224thereof is mainly emitted out from a lateral surface of the LED, and is projected onto the touch area110.

Referring toFIG. 4, the light guide strip230of the light guide module200according to the present invention wraps the light emitting element220. The light guide strip is molded, for example, in an extrusion molding manner or an injection molding manner, and assumes a cuboid shape. A lateral surface facing the touch area110of the light guide strip230is a first surface231, a third surface233is parallel to the first surface231, and a second surface232connects upper surfaces of the first surface231and the third surface233. In this embodiment, a light-proof surface234may also be added to the second surface232of the light guide strip230, so as to mask the light rays emitted by the light emitting element220from the second surface232, thereby avoiding causing light ray interference and influencing touch precision when the light rays are emitted to a non-touch area.

In order to enable the brightness of the optical touch panel100to be more uniform and to utilize the light source of the light emitting element220more appropriately, in the light guide module200according to the present invention, a reflecting component235may be further added to the second surface232or the third surface233, or even reflecting components235are added to the second surface232and the third surface233simultaneously. Therefore, the light rays emitted to the second surface232or the third surface233are reflected onto other surfaces due to being irradiated to the reflecting component235, so as to increase the probability of the light rays being emitted out from the first surface231, thereby increasing the brightness and uniformity of the optical touch panel.

Referring toFIG. 5, in the light guide module200according to the present invention, in order to enable the brightness of the optical touch panel to be more uniform and to utilize the light source of the light emitting element220more appropriately, a pattern236may be further added to the third surface233of the light guide strip230, so as to enable the light rays to be irregularly reflected at the time of passing through the third surface233.

The light guide strip230of the optical touch panel according to the present invention wraps the light emitting element220in the extrusion molding manner or the injection molding manner, so compared with the prior art, in the present invention, a light emitting element and a light guide strip of a conventional optical touch screen are integrated into a single light guide module200, thereby reducing assembling steps of the optical touch panel. The assembling of the optical touch panel is illustrated hereinafter. Referring toFIGS. 6A to 6C, a modular light guide module200is directly disposed at a side edge of the panel100, and the sensing element300is disposed on the panel100and is located at a corner of the touch area110.

In order to make the brightness of the optical touch screen more uniform, referring toFIGS. 7A and 7B,FIG. 7Ais a schematic three-dimensional view of an optical touch panel according to a second embodiment of the present invention, andFIG. 7Bis a schematic enlarged view of a light guide module inFIG. 7A. In the light guide module200according to the present invention, the printed circuit board210further has a plurality of light emitting elements220disposed thereon. The contact surface between the printed circuit board210and the light emitting element220is rectangular. The light emitting elements220are electrically disposed on the contact surface of the printed circuit board210, and the light emitting elements220are disposed on the contact surface along a long side of the contact surface at a predetermined interval. A light transmissive plastic240is molded above the contact surface of the printed circuit board210in a manner of extrusion molding or injection molding, and covers the light emitting elements220. The light transmissive plastic240is the light guide strip230.

The light guide strip230of the optical touch panel according to the present invention wraps the light emitting elements220and the reflecting component235in the extrusion pressing molding manner or the injection molding manner, in which the reflecting component235may also be attached to an external surface of the light guide strip230, so compared with the prior art, in the present invention, three internal components comprising an LED, a light guide element and a reflecting sheet of a conventional optical touch screen are integrated into a single light guide module200, thereby shortening assembling time of the optical touch panel.

Additionally, the reflecting sheet is assembled in the light guide module200, so interference of the light rays is performed in the light guide module200, and then the light rays are projected onto the touch area110, so as to solve the problem that the interference of the light rays is generated in the touch area110to cause redundant light rays to be projected into a photo-sensitive element, thereby reducing touch precision in the prior art. Likewise, in the optical touch panel according to the present invention, the reflecting component235makes the brightness of the optical touch panel more uniform.

Moreover, a plurality of light emitting elements220of the optical touch panel according to the present invention is distributed on the printed circuit board210at a predetermined interval, so besides being capable of increasing the brightness of the optical touch panel due to the increased number of the light emitting elements220, the uniformity of the optical touch panel may also be increased since the light rays are emitted into the touch area110from different angles.