JPH0327936B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a coordinate input device that detects coordinate information of a pressurized position by pressurizing a writing instrument or the like.

(Background Art) A coordinate input device using an input board has conventionally been used as a device for detecting the coordinates of a pen position in a device for inputting characters or figures into a computer or the like, for example, a handwritten character input device.

1 and 2 are a sectional view and a block diagram showing an example of an input panel of a conventional coordinate input device. 1st
The figure is a cross-sectional view showing the configuration of the input panel, where 1 is an insulating film, 2 is a conductive film, 3 is a pressure sensitive rubber, 4 is a resistive film, and 5
6 is a resistive terminal plate made of a resistor having a resistance value sufficiently smaller than that of the resistive film 4, and 6 is an insulating film plate. Note that the insulating film 1 and the conductive film 2 are made of flexible materials.

Alternatively, the pressure-sensitive rubber 3 may not be inserted between the conductive film and the resistive film 4, but may be left empty as is well known.

FIG. 2 is a block diagram centered on the resistive film 4, and 7 to 10 are terminal groups provided on the resistive terminal plate 5. Among these, terminals 7a and 8a are the leftmost terminals of the terminal groups 7 and 8, and 7b , 8b are the rightmost terminals of the terminal groups 7 and 8. (The terminals of each terminal group are provided at substantially the same spacing as adjacent terminals.) Reference numerals 11 to 18 are switches connected to each terminal on the resistor terminal board 5 as shown in FIG. 19 is a DC power supply, 20 is a writing instrument,
Reference numeral 20a indicates a pressure point applied by the writing instrument 20 through the insulating film 1. As shown in FIG. 2, a resistive terminal plate 5 made of a resistor having a sufficiently smaller resistance value than the resistive film 4 is arranged around the resistive film 4 and electrically connected thereto.

When trying to obtain the coordinates in the vertical direction, if each contact of each switch 11 to 18 becomes connected with a solid line at a certain timing, terminal group 7
Voltage E [V] is applied to terminal group 8, including terminals 7a and 7b, and O is applied to terminal group 8, including terminals 8a and 8b.
[V], the terminal group 9 and the terminal group 10 are in an open state, and a potential gradient in the vertical direction is obtained in both the resistive film 4 and the resistive terminal plate 5. The potential difference at this time is E [V].

When the contacts of each switch 11 to 18 become connected to the dotted line at the next timing, terminals 7b and 8
A voltage E [V] is applied to b and the terminal group 10,
Terminals 7a, 8a and terminal group 9 are connected to O[V], and terminal group 7 and terminal 8 excluding terminals 7a, 7b are connected to O[V].
The terminal group 8 excluding a and 8b is in an open state, and a potential gradient from right to left is obtained in both the resistive film 4 and the resistive terminal plate 5.

In this way, the vertical and horizontal coordinates of the point 21 pressed by the writing instrument 20 are obtained as potentials by the conductor film 2 via the pressure-sensitive rubber 3. Therefore, pressurization point 2
In order to accurately detect the coordinate information of 1, for example,
Vertical direction, E [V] to terminal group 7, terminal group 8
When O[V] is applied to terminal group 7 to terminal group 8, a linear potential gradient from E[V] to O[V] must be obtained at all points in the lateral direction. This also applies when voltage is applied in the lateral direction. That is, the terminal board 5 and the resistive film 4 are required to have uniform resistance values. This is relatively not a problem when the size of the resistive film is small, but as the resistive film becomes larger, it becomes difficult to obtain a uniform resistance value in manufacturing. In particular, it is more difficult to obtain a uniform resistive film with a resistive film that is coated over the entire surface than with a narrow terminal board due to manufacturing issues such as film thickness control. This had the disadvantage that it affected the potential gradient and made it impossible to obtain accurate positional information.

(Problems to be solved by the invention) An object of the present invention is to eliminate this drawback and provide a coordinate input device that performs potential correction. By applying electricity to form different potential surfaces depending on the position on the resistive film, and applying pressure to the conductor film laminated on the resistive film through the pressure-sensitive rubber film or the air gap, the potential corresponding to the pressure point is created. In a coordinate input device that leads to a conductive film, long and narrow resistive pieces with a resistance value sufficiently lower than that of the previous resistive film are placed in contact with the resistive film at intervals in a grid pattern in the vertical and horizontal directions. The coordinate input device is provided with a uniform potential gradient across the resistive film by electrically connecting the intersections of the resistive pieces.

(Structure and operation of the invention) FIG. 3 is a configuration diagram of an input panel showing an embodiment of the present invention, and the input panel as shown in FIG.
A cross-sectional view taken at section A' is shown. The resistive film 4 has
As shown in FIG. 4, a long and narrow resistor piece 21 has a resistance value similar to that of the terminal plate 5 but sufficiently lower than that of the resistive film 4.
~24 are embedded in a grid pattern. Further, the resistive film 4, the terminal plate 5, and the resistive pieces 21 to 24 are electrically connected at the portions where they contact each other.

FIG. 4 is a plan view of the input panel section to more clearly show the operation of the present invention, and the pressure-sensitive rubber 3, insulating film 1, conductive film 2, and resistive film peripheral circuit connections are omitted for simplicity. . First, when applying voltage in the vertical direction, that is, E [V] to terminal group 7 and O to terminal group 8.
When [V] is applied, the voltage from E[V] to O[V] is applied in the vertical direction of the terminal plate 5 and the resistive film 4 and the resistor pieces 21 and 22.
A potential gradient of up to Here, since it is relatively easy to make the resistance values of the narrow and low-resistance terminal plates and resistor pieces 21 to 24 uniform throughout, a linear potential gradient can be obtained. Therefore, the potential gradients of the vertical resistance pieces 21 and 22 are the same, so the horizontal line segments 23 and 24 of the resistance pieces have the same potential.
Furthermore, since the resistance values of the terminal plate 5 and the resistive pieces 21 to 24 are sufficiently low compared to the resistance value of the resistive film 4, the terminal plate 5 and the resistive pieces 21 to 24 can be regarded as conductors with respect to the resistive film 4. Therefore, the influence of potential disturbance due to non-uniform resistance value of the resistive film 4 is limited to the terminal plate 5 and the resistive pieces 21 to 24.
It has almost no effect on the potential gradient determined by . For example, in the resistive film 4, if the resistance value is non-uniform in the block indicated by the shaded area 4a, the potential gradient within the block 4a will be disturbed and will no longer be linear. pieces 21-24
It does not affect the resistive films of other blocks. That is, the potential gradient within each block of the resistive film 4 divided by the resistive pieces 21 to 24 is defined by the potential of the resistive pieces 21 to 24 in contact with that block and the variation in resistance value within the block, and is determined by the influence of other blocks. I don't receive it. Therefore, by increasing the number of resistor pieces 21 to 24, potential errors due to non-uniformity of the resistive film can be reduced with respect to the overall potential gradient.

Next, when a voltage is applied in the horizontal direction, that is, when E [V] is applied to the terminal groups 10, 7b, and 8a, and O [V] is applied to the terminal groups 9, 7a, and 8a, the resistive film 4 is Potential errors due to non-uniform resistance values can be reduced.

In the above embodiment, the lattice resistor may be made integrally with the terminal board using the same resistance material as the terminal board, or may be made of a thin metal wire or the like having an appropriate resistance value of about 0.1Ω/cm to 10Ω/cm. may be embedded in the resistive film. If a thin pattern is required, metal wires have the advantage of being easier to obtain uniform resistance. Also, the resistive film is usually thin, several tens of micrometers, so as long as it is electrically connected to the resistive piece, there is no need to embed it inside the resistive film.
For example, the same effect can be obtained by coating a resistive film on a resistive piece or by forming a resistive piece on a resistive film.
Furthermore, due to the large resistance film and the shape of the rollers, etc.
If it cannot be formed by multiple coatings or printing, it is easy to make the size larger by applying additional coatings by placing the seam above the resistor piece.

(Effects of the Invention) As explained above, in the embodiment, the resistive piece embedded in the resistive film is used as a potential gradient, and the resistive film is used as a conductor, so that the non-uniform resistance of the resistive film is affected. This is not only extremely advantageous in the production of resistive films, but also enables the provision of large-sized resistive films.

Note that it is desirable that each terminal of the terminal groups 7 to 10 be provided at least on an extension line of the resistance pieces 21 to 24, and further provided on the four sides of the resistance terminal board 5.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of an input panel of a conventional coordinate input device, FIG. 2 is a block diagram showing an example of a conventional coordinate input device, and FIG. 3 is a block diagram of an embodiment of the present invention. FIG. 4 is a detailed diagram of a resistive film according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Insulating film, 2... Conductor film, 3... Pressure sensitive rubber, 4... Resistive film, 5... Resistance terminal board, 6... Insulating substrate, 7-10... Terminal group, 7a... Terminal group 7
The leftmost terminal of 7b...the rightmost terminal of terminal group 7,
8a...Leftmost terminal of terminal group 8, 8b...Rightmost terminal of terminal group 8, 11-18...Switch, 19
...DC power supply, 20... Writing implement, 20a... Pressure point, 21 to 24... Resistance piece, A-A'... Cross section.

Claims (1)

[Claims] 1. A planar resistive film is alternately energized in the vertical and horizontal directions to form different potential surfaces depending on the position on the resistive film, and is laminated on the resistive film via a pressure-sensitive rubber film or a gap. In a coordinate input device that derives a potential corresponding to a pressurized point to a conductive film by applying pressure to a conductive film, a long and narrow resistor piece having a sufficiently lower resistance value than the resistive film is connected to the resistive film. The electrical potential gradient of the resistive film is made uniform by arranging the resistive films at intervals in a grid pattern in the vertical and horizontal directions so as to make contact with the resistive film, and by electrically connecting the intersections of the resistive films. Coordinate input device.