Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Reexamination Certificate
1998-08-19
2002-07-02
Shah, Kamini (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
C702S095000, C702S056000, C178S018040, C178S019020, C345S176000, C345S177000
Reexamination Certificate
active
06415240
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a coordinates input apparatus and sensor attaching structure and method. More particularly, the invention relates to a coordinates input apparatus for detecting an elastic wave oscillation inputted to an oscillation propagating plate by a plurality of sensors attached to the oscillation propagating plate and for detecting coordinates of an oscillation input point on the basis of a propagation time of the elastic wave oscillation and also relates to its sensor attaching structure and method.
2. Related Background Art
Generally, as an oscillation detecting device (hereinafter, also referred to as an oscillation sensor) to detect an oscillation which propagates in an object, piezoelectric ceramics such as lead zirconate titanate (hereinafter, abbreviated to “PZT”) or the like is used. A shape, an oscillating mode, and the like of such an oscillation detecting device are set so as to efficiently detect an acoustic wave of a predetermined frequency of an oscillation which propagates in the object. That is, to efficiently detect the oscillation, a device shape is determined so as to make a mechanical resonance frequency of the sensor coincide with a frequency of the detected acoustic wave and a sensitivity of the device or an attaching method of the device is determined in consideration of an oscillating mode or the like of the oscillation to be detected.
A conventional example of a coordinates input apparatus for calculating position coordinates of an oscillation input point by measuring an arrival delay time of an acoustic wave from an oscillation generating source by using such a kind of oscillation sensor has been shown in JP-A-61-33525 (Japanese Patent Application No. 59-153118). JP-A-61-33525 discloses a method of adhering and fixing the oscillation sensor to a desired position of an oscillation propagating plate and obtaining an electric conduction by a lead wire from the oscillation sensor.
Further, for instance, in JP-A-01-68823 (Japanese Patent Application No. 62-225393) and JP-A-01-114927 (Japanese Patent Application No. 62-273962), there is disclosed an example in which a guide to position a sensor is provided, the sensor is fitted into an engaging hole formed in the guide, thereby positioning the sensor, and the positioned sensor is come into pressure contact and fixed to the oscillation propagating plate by a spring force or the like.
In such a kind of coordinates input apparatus, an arrival delay time of the wave from an oscillation generating source to each oscillation detecting device is first measured and a distance between an oscillation input point and each oscillation detecting device is calculated by the product of an acoustic velocity of the wave and each delay time, respectively. As a basic principle, the position coordinates of the oscillation input point are geometrically calculated from the distance information and the arrangement of the sensors. Therefore, to accurately calculate the coordinates, it is necessary to accurately obtain the position of the oscillation detecting device or to accurately fix the oscillation detecting device at a desired position.
The above conventional example, however, has the following problems.
According to JP-A-61-33525, to obtain an electric conduction with the oscillation detecting device, a lead wire is attached to an electrode of the oscillation detecting device by means such as solder or the like. Therefore, characteristics of the oscillation detecting devices vary in dependence on an amount of solder or a soldering position and it is difficult to obtain a stable signal from each oscillation detecting device. That is, although a plurality of oscillation detecting devices are necessary to calculate the coordinates, the characteristics of the device are deteriorated due to the foregoing electrode taking means and it is difficult to construct a plurality of detecting devices having the same characteristics.
Particularly, in case of using such a coordinates input apparatus to a pen input computer such that the coordinates input apparatus and an output apparatus such as a display or the like are overlappingly arranged and a process can be performed with a feeling as if the user executed it by using a paper and a pencil, even in consideration of portability or the like of the apparatus, a size of the oscillation detecting device itself is restricted and it is easily presumed that a small detecting device is ordinarily used. In such a case, therefore, even if a solder amount is small, an influence on the characteristics of the oscillation detecting device by the solder amount cannot be ignored. Therefore, some compensating means including an adjustment or the like is necessary and it becomes not only a cause of an increase in costs but also an obstacle to realize a mass production of the apparatus.
Further, generally, an electric energy which is generated by the foregoing oscillation detecting deice itself is very weak and noises have to be sufficiently considered until the signal is amplified by amplifying means. That is, the wirings are complicated and the productivity is remarkably low because of various factors such as a countermeasure for noises and the like in addition to a device shape of the oscillation detecting device and a restriction on the characteristics.
On the other hand, in JP-A-01-68823 and JP-A-01-114927, by arranging an electrical contact to a position on an axis of the oscillation detecting device by a spring force without using any means such as solder or the like, a working efficiency is improved. However, the mass productivity is not sufficiently improved due to the wiring of lead wires or the like, the construction of a shield, or the like. The above conventional technique also has the following new problems.
As shown in the construction shown in JP-A-6133525, in case of adhering the oscillation detecting device to the oscillation propagating plate as one member, the oscillation detecting device can be accurately adhered and fixed onto the oscillation propagating plate by using an XY stage using an excellent positioning precision such as a tool of high precision, for example, a linear scale or the like and an image processing technique. However, according to the constructions shown in JP-A-01-68823 and JP-A-01-114927, although the sensor is positioned by the engaging hole formed in the guide, it is not easy to correctly set the position of the guide.
A fact that the position of the guide cannot be correctly set results in that the position of the oscillation sensor cannot be correctly set, causing a trouble of deterioration of the coordinates detecting precision. That is, in such a kind of coordinates input apparatus, the distance between the oscillation input point and each oscillation sensor is derived by the arrival time of the wave and the acoustic velocity and the position of the oscillation input point is derived from geometrical arrangement information of the oscillation sensors. Therefore, if an error is included in the arrangement of the oscillation sensors, a coordinates calculating precision deteriorates merely due to such an error.
Explanation will now be made by using specific numerals. There is a case where the relative distance of the oscillation detecting device is equal to, for example, about 500 mm in dependence on a use object. It is technically very difficult to mass-produce the apparatus at a mechanical working precision by setting a tolerance for the distance 500 mm to ±0.05 mm (tolerance is equal to 0.01%). Even if a working technique which enables such a construction exists, the costs are very high and become a large obstacle to realize the mass production of the apparatus. In the conventional technique as mentioned above, a positioning precision of the oscillation detecting device depends on the working precision when the apparatus is mass-produced. For example, now assuming that the tolerance of 0.1% (namely, working precision of ±0.5 mm) exists for the distance 500 mm, a coordinates
Kobayashi Katsuyuki
Sato Hajime
Tanaka Atsushi
Yanagisawa Ryozo
Yoshimura Yuichiro
Fitzpatrick ,Cella, Harper & Scinto
Shah Kamini
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