JPH062449U - Digitizer with display function - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a digitizer that can obtain sufficient detection sensitivity even if a display function is added. A plurality of transmitting coil groups arranged in parallel in a first direction, a plurality of receiving coil groups arranged in parallel in a second direction orthogonal to the first direction, and the transmitting coil A transmitter circuit connected to the transmitter group and sequentially applying current to the transmitter coil, a sense circuit connected to the receiver coil group and sequentially detecting a voltage induced in the receiver coil, and connected to the transmitter circuit and the sense circuit The tablet is provided with a processing circuit for controlling these operations and calculating the indicated coordinates, and the display device is provided on the tablet, and the receiving coil group is arranged on the display surface side of the display device. It is arranged on the back side of the display device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a digitizer using electromagnetic coupling, and more particularly to a digitizer having a display function.

[0002]

[Prior art]

 Conventionally, as a digitizer of this type, there is a device disclosed in Japanese Patent Publication No. 56-9728. This device includes a transmitter coil group, which is a plurality of driving wire groups arranged in a first direction, a receiver coil group, which is a plurality of sense line groups arranged in a second direction orthogonal to the transmitter coil group, A position indicator composed of a coil and a switch is provided, and a magnetic field generated by supplying a current to the transmitter coil group and the position indicator are magnetically coupled to generate an induced voltage in the receiver coil group. It was something to detect.

Due to technological innovation in recent years, digitizers have been extremely diverse in form, and an attempt has been made to enhance the functionality by adding a display function to a digitizer that has been conventionally used exclusively for input.

[0004]

[Problems to be solved by the device]

 However, the conventional digitizer with a display function has a problem that sufficient detection sensitivity cannot be obtained. The present invention has been made in view of this point, and an object thereof is to provide a digitizer capable of obtaining sufficient detection sensitivity even if a display function is added.

[0005]

[Means for Solving Problems]

 Therefore, the digitizer with a display function of the present invention comprises a plurality of transmitting coil groups arranged in parallel in a first direction and a plurality of receiving coils arranged in parallel in a second direction orthogonal to the first direction. A coil group, a transmission circuit connected to the transmission coil group and sequentially applying current to the transmission coil, and a sense circuit connected to the reception coil group and sequentially detecting the voltage induced in the reception coil. The display circuit is provided with a processing circuit that is connected to the transmission circuit and the sense circuit and controls these operations and calculates the designated coordinates, and that the receiving coil group is provided on the display surface side of the display device. The transmitter coils are arranged on the back side of the display device.

[0006]

[Action]

 The receiving coil group is arranged on the display surface side of the display device, and the transmitting coil group is arranged on the rear surface side of the display device. Therefore, the receiving coil group is strongly coupled to the magnetic field emitted from the position indicator. Further, with respect to the transmitting coil group, since the coils can be arranged at variable intervals and the strength of the supply current can be varied, it is easy to generate a magnetic field that can reach the position indicator even on the back side of the display device. . Therefore, when viewed as a whole device, the efficiency of electromagnetic coupling is improved, and sufficient detection sensitivity can be obtained.

[0007]

【Example】

 FIG. 1 is a view for explaining the present invention and is an exploded perspective view of a tablet. In the figure, the tablet 1 includes a transmitter coil group 11, a selection circuit 111 connected to the transmitter coil group 11 to switch the transmitter coils, a transmitter circuit 112 connected to the selector circuit 111, and a receiver coil group 12, A selection circuit 121 connected to the reception coil group 12 for switching connection of the reception coils, a sense circuit 122 connected to the selection circuit 121, a liquid crystal display device 13, and a display control circuit 132 connected to the liquid crystal display device 13. And the processing circuit 14 connected to the transmission circuit 112, the reception circuit 122, and the display control circuit 132, respectively.

The receiving coil group 12 is supported by a transparent member such as acrylic, and is fixed to the display section 131 side of the liquid crystal display device 13 by an appropriate means such as adhesion. Further, since a thin conductive wire having a wire diameter of about 0.1 to 0.3 mm is used for the receiving coil, the display unit 131 can be visually recognized through the receiving coil group 12. In addition, a capacitor (not shown) is connected to the end of the receiving coil on the side of the selection circuit to improve the detection sensitivity. The transmitter coil group 11 is supported by a printed circuit board or the like and is arranged on the back surface side of the liquid crystal display device 13 opposite to the display portion 131.

The position pointing operation in the apparatus of this embodiment is the same as the conventionally known one, and its outline is as follows. The oscillation circuit 112 supplies a predetermined current to the selection circuit 111 in response to the operation signal from the processing circuit 14, and the selection circuit 111 sequentially switches and connects the coils of the oscillation coil group 11 to apply this current. . A magnetic field is generated around the coil by the current applied to the transmitting coil, and the generated magnetic field is tuned with the resonance circuit of the position indicator 2 to induce a current in the resonance circuit. The resonant circuit generates a magnetic field by itself due to the induced current, and this magnetic field is coupled with the coil of the receiving coil group 12 and induces a voltage to the receiving coil. The sense circuit 122 detects the voltage induced in the receiving coil. At this time, the selection circuit 121 sequentially detects the induced voltage for each coil, and the sense circuit 122 obtains the distribution of the induced voltage. The processing circuit 14 calculates the pointing coordinate of the position indicator 2 from the distribution of the operation signal given to the transmitting circuit 112 and the induced voltage obtained by the sensing circuit 122. Further, the processing circuit 14 sends out the detection result to the host device based on the operation result, or sends out the display signal to the display control circuit 132 to display the data on the display section 131.

Next, the electromagnetic coupling operation in the apparatus of the embodiment will be described with reference to FIGS. 2 and 3. FIG. 2 is a diagram for explaining the connection of the transmitting coil group 11. The current applied from the oscillator circuit 112 is sequentially supplied to the oscillator coil group 11 via the selection circuit 111. Since this current flows through the coil along the path indicated by the arrow in the figure, the direction of the current flowing through the coil is opposite in the detection area. Therefore, the magnetic field generated by the supply of the current is generated in a circular shape centered on the coil as shown in FIG. 3, and the magnetic fields emitted from the adjacent coils are in opposite directions. In the figure, a clockwise magnetic field is generated in the transmitting coils 11-1, 11-3 and 11-5, and a counterclockwise magnetic field is generated in 11-2 and 11-4.

Here, when the disposition interval L of the transmission coils is short, the magnetic fields generated by the adjacent coils cancel each other out, so that this magnetic field cannot reach the position indicator 2. Further, when the current applied to the transmission coil is weak, the radius of the generated magnetic field becomes small, and in this case also, the magnetic field cannot reach the position indicator 2. Therefore, in the apparatus of this embodiment, the intensity of the current applied from the transmission circuit 112 to the transmission coil is set so that the generated magnetic field reaches the position indicator 2, and the coil arrangement interval L is set at an interval that does not cancel the generated magnetic field. To be

The magnetic field reaching the position indicator 2 in this way tunes with the resonance circuit in the position indicator 2 to induce a current in the resonance circuit. The position indicator 2 generates a magnetic field by the induced current, and this magnetic field is coupled to the receiving coil near the receiving coil group 12 arranged on the display surface side of the liquid crystal display device 13. At this time, since the receiving coil group 12 and the position indicator 2 are in a very close positional relationship, the coupling efficiency between them is high. Therefore, even if the magnetic field generated from the position indicator 2 is not so strong, it is sufficient. Detection sensitivity is obtained. Therefore, the electromagnetic coupling efficiency is improved when viewed as the entire device.

Note that the device of the embodiment is of a system in which the position indicator does not have a capacitor, but the present invention is not limited to this, and for example, in a system of having a capacitor in the position indicator. Similar effects are obtained.

[0014]

[Effect of device]

 As described above, in the digitizer with a display function of the present invention, the receiving coil group is arranged on the display surface side of the liquid crystal display device, and the transmitting coil group is arranged on the rear surface side of the liquid crystal display device. Therefore, it has an advantage that the electromagnetic coupling efficiency of the entire apparatus is improved and sufficient detection sensitivity is obtained. Further, since only the receiving coil group is arranged on the display surface side of the display coil group, the visibility of the display section is improved compared to a device in which both transmitting and receiving coils are arranged on the display surface side. It also has the advantage.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of the present invention.

FIG. 2 is an explanatory diagram showing a path of a current applied to a transmitting coil group.

FIG. 3 is an explanatory view showing a state of electromagnetic coupling in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 tablet 11 transmitting coil group 112 transmitting circuit 12 receiving coil group 122 sense circuit 13 liquid crystal display device 131 display unit 132 display control circuit 14 processing circuit 2 position indicator

Claims (1)

[Scope of utility model registration request] 1. A digitizer for detecting pointing coordinates on a tablet pointed by a position pointing device, comprising a plurality of transmitting coil groups arranged in parallel in a first direction and orthogonal to the first direction. A plurality of receiving coil groups arranged in parallel in the second direction, a transmitting circuit connected to the transmitting coil group and sequentially applying current to the transmitting coil, and connected to the receiving coil group for receiving. The tablet is provided with a sense circuit that sequentially detects the voltage induced in the coil, a processing circuit that is connected to the transmission circuit and the sense circuit, controls the operation of these circuits, and calculates the indicated coordinates, and a display device. The receiving coil group is disposed on the display surface side of the display device,
A digitizer with a display function, in which the transmitter coils are arranged on the back side of the display device.