JPH0454518Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> The present invention includes an electromagnetic induction type tablet sense board placed on the bottom surface of the liquid crystal display, which detects the magnetic flux of an input pen located on the top surface of the liquid crystal display. The present invention relates to a handwriting input device that displays handwritten characters input with the input pen.

<Prior Art> In a handwriting input device, it is difficult to use EL (electroluminescence) having an electrode using an aluminum sheet as a backlight. This is because electromagnetic waves cannot pass through the aluminum sheet, and when used, the aluminum electrode must be made considerably thinner by vapor deposition or the like, which poses a technical problem.

<Purpose of the invention> In view of the above circumstances, the invention has been developed by forming one electrode of the EL panel with silver-Ag paste.
We provide a handwriting input device that incorporates an EL panel into the backlight.

<Example> The configuration of the present invention will be explained below.

FIG. 1 is a sectional view of a handwriting input device according to an embodiment of the present invention.

In the figure, 1a and 1b are glass substrates facing each other, which seal a liquid crystal 3 together with a sealing material 2.

On the outside of each glass substrate 1a and 1b,
Polarizing plates 4a and 4b are attached, and transparent electrodes 5a and 5b are formed inside them, respectively.

A tablet sense substrate 7 is disposed on the lower surface (back side of the display surface) of the liquid crystal display 6, and detects the magnetic flux of the input pen 8 located on the upper surface (display surface) of the liquid crystal display 6.

In this embodiment, an EL panel 9 having the structure shown in FIG. 2 is inserted into the gap between the liquid crystal display 6 and the tablet sense substrate 7.

In FIG. 2, 10a and 10b are polyester films, one film 10a has a transparent electrode 11 formed thereon, and the other film 10b has a silver paste electrode 12 formed thereon. In addition,
13 is an insulating sealant, and both electrodes 11 and 12
are pasted together.

As described above, since the EL panel 9 whose one electrode 12 is made of silver paste is used as a backlight, the magnetic flux from the input pen 8 passes through the EL panel 9 and is directed to the tablet sense board 7. reach. It is known that the liquid crystal display 6 has no effect on the passage of magnetic flux.

The fact that the silver-based electrode 12 does not affect the passage of electromagnetic waves in this way is because the penetration length δ of electromagnetic waves is expressed by the following formula.

δ=√2 (However, ω represents the angular frequency, μ represents the magnetic permeability, and σ represents the electrical conductivity.) In other words, the aluminum electrode has a large electrical conductivity σ,
Therefore, the penetration length δ of electromagnetic waves becomes shorter.

However, when silver paste electrodes are used, the conductivity σ becomes small because the silver particles are microscopically large, and as a result, the penetration length δ of electromagnetic waves becomes long.
The electromagnetic waves pass through the back light's EL panel 9,
The tablet sense board 7 is reached.

<Effects> As described above, the handwriting input device of the present invention uses silver paste for the electrodes on the back side of the EL panel, so electromagnetic waves can pass through it, and the silver paste electrodes can be printed. Not only is it easy to manufacture using technology and reduces costs, but the silver paste electrode also serves as a reflector and reflects the light from the EL panel, which is the backlight, so it illuminates the liquid crystal display above without waste. This reduces the number of parts and allows the handwriting input device to become thinner.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a handwriting input device to which the present invention is applied, and FIG. 2 is a structural diagram of an EL panel incorporated in the handwriting input device. 6...Liquid crystal display, 7...Tablet sense substrate, 12...Silver paste electrode.

Claims (1)

[Claims for Utility Model Registration] An electromagnetic induction type tablet sense board is placed on the bottom surface of a transmissive liquid crystal display, detects the magnetic flux of an input pen located on the top surface of the liquid crystal display, and detects the magnetic flux of an input pen located on the top surface of the liquid crystal display. In the handwriting input device on which handwritten characters inputted by the user are displayed, an EL panel for backlighting is arranged in the gap between the liquid crystal display and the tablet sense board,
A handwriting input device characterized in that an electrode on the back side of the EL panel is formed of silver paste.