JP2005251109A - Pointing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pointing device wherein current noise of a strain sensor is small and a temperature characteristic is favorable even when a resin substrate with favorable flexibility is used. <P>SOLUTION: The pointing device is provided with the resin substrate 11, a stick member 15 erected on the resin substrate 11, a plurality of resistors 20A-20D formed on a rear face of the resin substrate 11, and an electrode 16 electrically connecting the resistors 20A-20D, and it detects change in resistance values of the resistors 20A-20D caused by deflection of the resin substrate 11 following displacement of the stick member 15. The resistors 20A-20D are coated with a nickel-based alloy by electroless plating. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pointing device, and more particularly to a pointing device that is mounted on a notebook personal computer or the like and used as an input means for moving a pointer or cursor on a screen.

  In general, a pointing device mounted as an input means on a notebook computer or the like, as described in Patent Document 1, the substrate bends according to the pressing direction of the stick member, and the amount of bending (distortion) is applied to the substrate. The change is detected as a change in the resistance value of the formed resistor.

  By the way, in some conventional pointing devices, a resin is usually used as a substrate material, and a carbon-based resistor is used as a resistor material. The resin substrate has good flexibility and is suitable as a material that receives a pressing force from the stick member. However, the carbon resistor constituting the strain sensor has a problem that current noise is large and temperature characteristics are poor. In particular, the pointing device is required from the market that the resistance value change of the resistor is small, so that the temperature characteristics are good and the current noise is small.

On the other hand, a strain sensor using a cermet resistor material as a resistor is known, and the cermet resistor has smaller current noise and better temperature characteristics than the carbon resistor. However, since the cermet resistor material has a firing temperature of 800 ° C. or higher, it can be formed on a substrate such as ceramics or glass hollow, but it cannot be formed on a resin substrate. When a substrate such as ceramics or glass enamel is used, there is a problem in that the flexibility is poor and the sensitivity is lowered as compared with a resin substrate.
JP 2001-236175 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a pointing device that uses a resin substrate with good flexibility but has low current noise in a strain sensor and good temperature characteristics.

  In order to achieve the above object, the present invention provides a resin substrate, a stick member standing on the resin substrate, a plurality of resistors formed on the resin substrate, and the plurality of resistors electrically A pointing device for detecting a change in the resistance value of the resistor due to bending of the resin substrate accompanying the displacement of the stick member, wherein the resistor is made of a nickel-based alloy. To do.

  In the pointing device according to the present invention, a nickel-based alloy is used as a resistor formed on a resin substrate as a strain sensor. Such nickel-based alloys have lower current noise and better temperature characteristics than conventional carbon-based resistance materials and cermet-based resistance materials (the rate of change in resistance value with respect to temperature changes is small). . In addition, since the nickel-based alloy can be formed by a plating method, it can be easily formed on a highly flexible resin substrate, and a highly sensitive pointing device can be obtained.

  Hereinafter, embodiments of a pointing device according to the present invention will be described with reference to the accompanying drawings.

  1 and 2 show a schematic configuration of the pointing device 10, and FIG. 3 shows an exploded state thereof. The pointing device 10 is generally composed of a resin substrate 11, a stick member 15, an electrode 16, resistors 20 </ b> A to 20 </ b> D, a flexible substrate 25, and a base 30.

  The resin substrate 11 is formed in a plate shape using a liquid crystal polymer, a glass epoxy resin, or the like. The resin substrate 11 may be selected from various materials other than those exemplified here as long as the material has good flexibility.

  The stick member 15 is made of a hard resin material or the like, and a lower portion thereof is fitted / adhered to the hole 12 of the resin substrate 11 and can swing in all directions of 360 ° with the fitting portion as a fulcrum.

  The electrode 16 is formed by depositing Ag, Cu or the like on the back surface of the resin substrate 11, and includes terminal portions 17a to 17f and connection portions 18a to 18h.

  Four resistors 20A to 20D are arranged on the back surface of the resin substrate 11 at equal intervals of 90 ° so as to straddle the pair of electrode connecting portions 18a, 18b, 18c, 18d, 18e, 18f, 18g, and 18h. (See FIG. 5). As the resistors 20A to 20D, nickel-based alloys are used, and specifically, nickel / copper / phosphorus alloys, nickel / iron / phosphorus alloys or nickel / tungsten / phosphorus alloys are preferably used.

  Each of the resistors 20A to 20D is electrically connected to a wiring provided on the flexible substrate 25 via solder 21 (see FIG. 2) connected to the terminal portions 17a to 17f of the electrode 16 to form a known bridge circuit. As described below, it functions as a strain sensor in which the resistance value changes due to the bending of the resin substrate 11.

  Further, the resistors 20A to 20D are covered with an overcoat 24 made of an insulating material in order to insulate from the wiring on the flexible substrate 25. In place of the solder 21, a conductive adhesive or the like may be used.

  The base 30 is made of a hard insulating material, and holds the resin substrate 11 via the flexible substrate 25. Protrusions (not shown) provided in the positioning guide holes 31 a and 31 b of the base 30 protrude from the holes 25 a and 25 b of the flexible substrate 25, and the projections engage with the semicircular hole portions 13 a and 13 b of the resin substrate 11. The substrate 11 is positioned on the base 30.

  The base 30 is fixed to the keyboard plate 40 shown in FIG. 2 by caulking or burring using the fixing holes 32a, 32b, and 32c.

  Next, the operation of the strain sensor composed of the resin substrate 11 and the resistors 20A to 20D will be described.

  The stick member 15 can be tilted in any direction of 360 ° with the lower part as a fulcrum. For example, as shown in FIG. 6, when the force f acts from the resistor 20C side to the resistor 20A side, The resin substrate 11 is deformed with the joint portion 14 between the member 15 and the resin substrate 11 as an action point. In response to this deformation, the resistors 20A and 20C are also deformed to cause distortion.

  That is, the resistor 20C is deformed into a convex surface and slightly contracted, and the resistance value is lowered. Further, the resistor 20A is deformed into a concave surface and slightly extends, and the resistance value increases. On the other hand, the resistors 20B and 20D positioned in the direction orthogonal to the resistors 20A and 20C are only subjected to torsional stress in the direction of current flowing through the resistors 20A and 20C, and the change in resistance value is negligible. Thereby, the force only in the coordinate axis direction on the resistors 20A and 20C is detected.

  Also, when a force is applied from the resistor 20B side to the resistor 20D side, the force only in the coordinate axis direction on the resistors 20B and 20D is detected in the same manner as described above. Further, even when a force is applied in a random direction z, a tensile force acts on each of the resistors 20A to 20D to deform into a concave surface, and a force in the z direction is detected.

  In order to detect the direction of the force acting on the stick member 15 using the resistors 20A to 20D as described above, a bridge circuit is formed by the resistors 20A to 20D, and the two terminal portions 17a, 17b, and 17c of the electrode 16 are formed. , 17d, 17e, 17f, a predetermined voltage is applied. Then, a change in resistance value when the resistors 20A to 20D are distorted is detected as a voltage change, and the direction of the acting force is calculated based on this voltage change. Note that this type of calculation is well known and will not be described.

  Here, the characteristics of the pointing device 10 will be described in comparison with a conventional one.

  In general, the rate of change of the resistance value with respect to the temperature change of the resistor is ± 300 ppm for the conventional carbon resistor, and ± 50 ppm for the nickel alloy plating resistor of the present invention. That is, if a nickel-based alloy is used as the resistor, the rate of change of the resistance value with respect to the temperature change becomes small, and accurate detection is possible.

  When the measurement ratio of current noise voltage (μV) to applied current voltage (V) is measured using a resistance noise measuring device (manufactured by Quan-Tech, resistance noise measuring device 315C) with respect to current noise, a conventional carbon resistor Is 6.6 dB, the cermet resistor is −4.0 dB, and the nickel alloy plating resistor of the present invention is −33.5 dB. That is, if a nickel-based alloy is used as the resistor, the current noise is reduced, and there is an advantage that the influence of the noise is small even if the output value is amplified.

  The pointing device according to the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist thereof. In particular, the detailed structure and shape of the resin substrate, stick member, electrode, resistor, etc. are arbitrary. In addition, although the electroless plating method is used in the embodiment as a method for forming the resistor, the method is not particularly limited thereto, and for example, an electrolytic plating method may be used.

It is a perspective view which shows the pointing device which is one Example of this invention. It is sectional drawing which shows the mounting state of the said pointing device. It is a disassembled perspective view of the pointing device. It is a perspective view which shows the resin substrate and stick member which comprise the said pointing device. It is a bottom view of the resin substrate. It is explanatory drawing for showing the principle of operation of the pointing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Pointing device 11 ... Resin substrate 15 ... Stick member 16 ... Electrode 20A-20D ... Resistor

Claims (2)

A resin substrate; a stick member erected on the resin substrate; a plurality of resistors formed on the resin substrate; and an electrode that electrically connects the plurality of resistors. In a pointing device that detects a change in the resistance value of the resistor due to the deflection of the resin substrate accompanying the displacement,
A pointing device, wherein the resistor is made of a nickel-based alloy.   The pointing device according to claim 1, wherein the resistor is formed on the resin substrate by a plating method.

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