JPS6365470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying device and is improved so that it can be determined whether or not a stylus has correctly copied an object without jumping.

As shown in FIG. 1, a conventional copying device biases a stylus 3 from a tracer head 2 toward an object 1, and causes the stylus 3 to follow the object as the tracer head 2 moves. It is.
However, if the movement speed of the tracer head 2 is fast at a place where the shape of the object 1 suddenly changes, for example at a step, the stylus 3 cannot follow the surface shape of the object 1, and the shape of the object 1 changes rapidly. A phenomenon of release from the surface occurred.

If such a jumping phenomenon occurs, it means that the stylus 3 has not traced the surface of the object 1, so the moving speed of the tracer head 2 must be slowed down and the tracing must be performed again. Until now, there was no way to determine whether a phenomenon had occurred.

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a copying device that can determine whether or not a jumping phenomenon has occurred by electrically processing a stylus displacement signal. . The configuration of the present invention to achieve such an object is to bias the stylus against the surface of the object to displace it and detect the displacement of the stylus, and when the stylus is released from the object, based on the stylus displacement signal, In a copying device that generates a jumping detection signal, the three-dimensional displacement signals ε _x , ε _y , ε _z of the stylus are synthesized to generate a displacement signal ε (=
√ _x ^{2 +} _y ^{2 +} _z ² A comparison voltage generator generates a comparison voltage V _C corresponding to the maximum acceleration αmax, and a jumping detection signal is generated by comparing the comparison voltage V _C and the differential value d ² ε/dt ² and when d ² ε/dt ² = V _C and a comparator that generates.

Hereinafter, the present invention will be specifically explained based on Examples. Incidentally, the same parts as those in the prior art described above are given the same numbers and the description thereof will be omitted.

An embodiment of the present invention is shown in FIGS. 2 and 3.
As shown in the figure, in this embodiment, the three mutually orthogonal directions are defined as X, Y, and Z, and among these, the direction in which the stylus 3 is urged is defined as Z. That is, displacements x, y, and z of the stylus 3 in the X, Y, and Z directions are detected by displacement detectors 4, 5, and 6, respectively, and three-dimensional displacement signals ε _x , ε _y , and ε _z proportional to the displacements are detected, respectively. It is output to the displacement synthesizer 7 as a displacement synthesizer 7. After the displacement synthesizer 7 squares the three-dimensional displacement signals ε _x , ε _y , and ε _z and adds them,
Furthermore, the displacement signal ε (=√ _x ² + _y ² + _z ² ) is divided into squares.
Calculate. This displacement signal ε is output to a displacement differentiator 8 and a comparison voltage generator 9, respectively. In the displacement differentiator 8, the displacement signal ε is differentiated twice, and a differential value d ² ε/dt ² is calculated. On the other hand, in the comparison voltage generator 9, a comparison voltage V _C proportional to the displacement signal ε is calculated. The proportionality constant between the displacement signal ε and the comparison voltage V _C is determined in correspondence with the maximum acceleration α _nax that the comparison voltage V _C can cause to the stylus 3 . This is because, as will be described later, a jumping phenomenon occurs when the acceleration α of the energized stylus 3 is equal to the maximum acceleration α _nax . The differential value d ² ε/dt ² and the comparison voltage V _C are each output to the comparator 10 . In the comparator 10, these differential values d ² ε/dt ² and the comparison voltage V _C are compared, and the differential value d ² ε/d
Jumping detection signal A is output when t ² and comparison voltage V _C are equal. When the jumping detection signal A is output in this way, it is objectively recognized that the jumping phenomenon has occurred.

The copying device having the above configuration is used as follows. First, as shown in Figure 3A, stylus 3
When is free in the air without contacting the object, Z
Displacement in direction z = 0, that is, displacement signal ε _z = 0
During the copying operation, as shown in FIG.
The tracing control is performed so that the displacement becomes a preset target displacement z ₀ , that is, ε _z =ε ₀ . At this time, since the displacements x and y in the x and y directions are zero, the displacement signals ε _x and ε _y output from the detectors 4 and 5 are both zero. Therefore, the displacement signal ε synthesized by the displacement synthesizer 7 is as follows for cases (a) and (b).

In case (a), ε=√ _x ² + _y ² + _z ² =√0 ² +0 ² +0 ² =0 In case (b), ε=√ _x ² + _y ² + _z ² =√0 ² +0 ² + ₀ ² = ε ₀ Also, the force F by which the stylus 3 is urged against the object 1 by the spring in the tracer head 2 is (a),
In case (b), the situation is as follows.

In the case of (a), F=0 In the case of (b), F=F ₀ To summarize the above, as shown in Figure 4,
It can be seen that the displacement z and displacement amount ε of the stylus 3 in the Z direction are proportional to the force F that urges the stylus 3. Now, considering the maximum acceleration α _nax that the stylus 3 can follow along the surface of the object 1, it can be expressed as follows.

α _nax = −F/M=−K ₁・Z/M=−K ₂・ε/M…(1) However, M is the mass of the stylus, K ₁ is the spring constant of the spring that biases the stylus, K ₂ is a proportionality constant.

As is clear from FIG. 5 showing the relationship of equation (1) above, the maximum followable acceleration α _nax can be calculated as a value proportional to the displacement signal ε. The condition for the jumping phenomenon is that the displacement z of the stylus 3
When decreases, the acceleration α matches the maximum acceleration α _nax , that is, α=α _nax . The acceleration α of the stylus 3 can be expressed as shown in the following equation from the proportional relationship between the displacement z and the displacement signal ε.

α=d ² z/dt ² =K ₃ d ² ε/dt ² (2) where K ₃ is a proportionality constant.

Therefore, the condition α=
α _nax can be transformed as shown below.

α=α _nax K ₃ d ² ε/dt ² = −K ₂・ε/M …(3) d ² ε/dt ² =−K ₂ /K ₃ M・ε …(4) Differential value d ² ε/ dt ² is obtained by the displacement differentiator 8, while -K ₂ /K ₃ M·ε is obtained by the comparison voltage generator 9 using pre-stored constants K ₂ and K ₃ and the mass M of the stylus 3.
It is also calculated based on the displacement ε inputted from the displacement synthesizer 7 and obtained as the comparison voltage V _C .
These differential values d ² ε/dt ² and the comparison voltage V _C are compared in the comparator 10, and the comparator 10 detects when these differential values d ² ε/dt ² and the comparison voltage V _C become equal, that is, the above-mentioned A jumping detection signal A is output when the conditions for the occurrence of the jumping phenomenon shown in equation (4) are satisfied. If the jumping detection signal A is output, it means that the copying has not been performed normally, so the speed is reduced and the copying is performed again for that part.

As described above, according to the copying apparatus of the present invention, it is possible to immediately recognize that a jumping phenomenon has occurred based on the jumping detection signal A, so it is possible to determine whether copying has been performed normally, and also to detect jumping. Since the generation limit is known, the scanning speed can be increased as much as possible to shorten the scanning time. In this embodiment, the comparison voltage V _C is determined based on the mass M of the stylus 3 and the spring constant K ₁ of the spring that biases the stylus. When using the above means, the comparison voltage V _C may be determined based on another value corresponding to the spring constant; in any case, the comparison voltage V _C is determined based on the maximum acceleration α _nax that can occur in the energized stylus. Any corresponding value is sufficient.

As described above in detail based on the embodiments, according to the present invention, it is possible to determine whether the stylus has correctly traced the object based on the jumping detection signal, and it is possible to detect objects whose shape changes rapidly. This is particularly suitable for copying. Note that the copying device of the present invention can be applied to a die-sinking machine, a scanning machine, a three-dimensional measuring machine, and the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing how the stylus is released from the object, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. Figure B is an explanatory diagram showing the state during the copying operation, Figure 4 is a graph showing the relationship between displacement and the force applied to the stylus with respect to the displacement signal, and Figure 5
The figure is a graph showing the relationship between the maximum acceleration that can be tracked and the displacement signal. In the drawing, 1 is the object, 2 is the tracer head, 3
is a stylus, 4, 5, and 6 are position detectors, 7 is a displacement synthesizer, 8 is a displacement differentiator, 9 is a comparison voltage generator, 10 is a comparator, and A is a jumping signal.

Claims (1)

[Scope of Claims] 1. The stylus is biased against the surface of the object to be displaced and the displacement of the stylus is detected, and when the stylus is released from the object, a jumping detection signal is generated based on the stylus displacement signal. In the copying device that generates the _displacement signal _ε ( ₌
√ _x ^{2 +} _y ^{2 +} _z ² A comparison voltage generator generates a comparison voltage V _C corresponding to the maximum acceleration αmax, and a jumping detection signal is generated by comparing the comparison voltage V _C and the differential value d ² ε/dt ² and when d ² ε/dt ² = V _C A copying device comprising: a comparator that generates .