JPH074488Y2 - Contact detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a contact detection device, and in particular, it is a detection device that accurately outputs the moment when a contactor comes into contact with an object to be measured, and is generally called a touch probe. Regarding what is done.

[Conventional technology]

As a contact detector, Japanese Patent Publication No. 58-17402 is well known. This is because a closed circuit created by seated contacts arranged at three equally spaced points opens due to the attitude displacement of the contact (at least 1
Since the two seating contacts open), it detects the moment when the contactor touches the DUT.

However, in this contact detector, there is a time delay from the moment the contact strikes the object to be measured until a signal is emitted, and this time delay can be the same in all contact direction angles. However, there is a drawback in that a measurement error occurs due to the time difference.

Therefore, it is considered that not only the contact detection by the mechanical posture displacement of the contactor but also another high-sensitivity element is provided in parallel.

Japanese Examined Patent Publication No. 60-48681, published patent publication No. 62-501234,
In both cases, there is a description to detect the moment of contact by using a detecting device such as a piezoelectric element. In particular, JP-B-60-48681 discloses a detecting device such as a piezoelectric element based on a detection signal due to a mechanical posture displacement of a contact. There is a statement to confirm the suitability of the output signal of.

[Problems to be solved by the device]

However, the former requires the use of a protector for protecting the piezoelectric element (a tool for fixing the contactor attachment part) when the contactor is replaced, because tensile force may be applied to the piezoelectric element in addition to the compressive force. However, there was a drawback that the work was troublesome.

On the other hand, the latter has a drawback that the output of the piezoelectric element is not retained after the contact, and the determination of contact and noise is ambiguous.

The present invention has been made in view of the above circumstances, and provides a contact detection device capable of detecting a contact with high sensitivity and reliability, and having a simple structure and easy replacement of contacts. The purpose is to provide.

[Means for Solving the Problems]

In order to achieve the above object, the present invention comprises a central member having a contactor for contacting an object to be measured, and at least three seat portions for seating the central member, and a case for tiltably holding the central member. And a first detection means having a stress sensitive element disposed in each seat, which outputs a first detection signal based on the pressure applied via the central member, and the stress in each seat. A second detection unit having a seating contact formed on the sensitive element, and outputting a second detection signal when at least one seating contact opens due to the attitude displacement of the contactor; and the first detection unit. An electric circuit that outputs a contact signal at the time when the first detection signal is output when the second detection signal is output from the second detection means within a set time after the first detection signal is output from It is characterized by having.

[Action]

The present invention uses, in addition to the means for detecting contact based on the opening and closing of the seating contact formed in each seat, a stress sensitive element for detecting pressure fluctuations.

In other words, contact detection using seated contacts cannot be detected with high accuracy because there is a response delay from the moment the contactor hits the object to be measured until the signal is emitted, but contact with the object to be measured is reliably detected. can do. On the other hand, the stress-sensitive element has a high sensitivity and outputs a required signal at the moment when the contactor hits the object to be measured, but there is a possibility that the stress-sensitive element may also output a signal due to vibration or acceleration of the device.

Therefore, in the present invention, only when the contact is detected by the seating contact within a set time after the signal is output from the stress-sensitive element, the time when the signal from the stress-sensitive element is output is set as an effective contact signal. ing. This makes it possible to detect contact with high sensitivity and reliability.

Further, according to the present invention, since the seating contact is formed on the stress-sensitive element arranged in each seat, the structure is simple and no tensile force is applied to the stress-sensitive element when the contact is replaced. , Can be performed in the same manner as the conventional one having only the seating contact.

〔Example〕

In FIGS. 1 and 2, a central shaft 2 extends upward on the upper surface of a cylindrical case 1 and is inserted into the lower end of the vertical shaft of an apparatus, for example, a coordinate measuring machine. A shelf 3 is provided inside the lower portion of the cylindrical case 1. Here, as shown in FIG. 2, on the inner upper surface of the shelf 3, stress sensitive elements 5 and 6 such as a total of 6 pressure sensitive elements at a distance of 120 ° in the directions A, B and C, and a sphere 7, 8 are arranged. A, B, C3
Since the structures are exactly the same in the directions, only the direction A will be described below. Then, the spheres 7 and 8 are fixed on the stress-sensitive elements 5 and 6 at intervals.

A central member 4 is placed inside the cylindrical case 1. here,
On the central member 4, three pins 10 are radially projected in the directions A, B and C at intervals of 120 °, and the pins 10 are located between the two balls 7 and 8 described above. A pressurizing spring 13 is arranged between the central member 4 and the ceiling of the cylindrical case 1, and this spring can adjust the contact pressure of the three seating contacts by adjusting the screw 14.
Further, the pin 10 and the central member 4 are electrically insulated.

A known seating contact mechanism is formed between the balls 7 and 8 and the pin 10, and the seating contact circuit 40 (FIG. 3) is formed by electrically connecting the balls. That is, the seating contact circuit 40 is closed when the central member 4 is not tilted (when the three pins 10 are all seated between the two balls 7 and 8), When at least one pin 10 is lifted by the tilting motion of the central member 4 and the balls 7 and 8 are electrically opened,
Output the detection signal.

The output signal of each stress-sensitive element 5 is a voltage signal corresponding to the pressure applied through each pin 10 and the spheres 7 and 8 of the central member 4, and is led out of the case, as shown in FIG. For example, it is added to the one-shot circuit 42.

The one-shot circuit 42 includes one of the stress sensitive elements 5
When the output of is at a predetermined level, the pulse signal of the set time T is output. This pulse signal is used as a signal for reading the contact position signal at the time of its rising, and is also applied to the AND circuit 44.

The output signal from the seating contact circuit 40 is added to the other input of the AND circuit 44.
When a detection signal is applied from the seating contact circuit 40 within the pulse width (set time T) of the pulse signal, 44 outputs this as a determination signal for determining the read contact position signal as an effective position signal.

Next, the operation of the above mechanism will be described with reference to the timing chart shown in FIG.

At the moment when the contact 12 attached to the lower end of the central member 4 contacts the object to be measured, the central member 4 receives the reaction force. This reaction force acts on the three sets of seated contacts and first acts as a force for lifting or pressing down on the stress-sensitive elements 7 and 8 supporting each contact, whereby at least one stress-sensitive element is
For example, a signal indicating the pressure fluctuation is output from the contact time t ₀ shown in FIG. 4 (A), whereby the one-shot circuit 42 outputs a pulse signal that is at a high level from the time t ₀ to the set time T. (FIG. 4 (B)). Then, the position signal at time t ₀ is read by this pulse signal.

Then, when the contact force continues to act on the contactor 12, at least one of the three pins 10 of the seating contact is lifted, and the seating contact circuit 40 opens the circuit and outputs a detection signal (Fig. 4 ( C)).

Then, as shown in FIG. 4 (D), when the AND condition between the pulse signal (FIG. 4 (B)) and the detection signal (FIG. 4 (C)) is satisfied, the position signal read at the time t _0. Is a valid position signal.

When the signal from the seated contact circuit is not input within the set time T, the signal from the stress sensitive element or the like is treated as a noise signal, and the read position signal is not captured.

[Effect of device]

As described above, according to the contact detection device of the present invention,
A seating contact is provided on the stress-sensitive element, and only when the contact is detected by the seating contact within a set time after the signal is output from the stress-sensitive element, the time when the signal is output from the stress-sensitive element becomes a valid contact. Since the signal is used, it is possible to detect contact with high sensitivity and certainty.Because the structure is simple and no tensile force is applied to the stress-sensitive element when the contact is replaced, the stress-sensitive element is damaged. There is nothing to do.

[Brief description of drawings]

FIG. 1 is a sectional view of a contact detecting device according to the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a block diagram showing an example of an electric circuit of the contact detecting device according to the present invention. FIG. 4 is a timing chart used to explain the operation of the contact detection device according to the present invention. 1 ... Case, 3 ... Shelf, 4 ... Central member, 5, 6 ...
Stress-sensitive element, 7, 8 ... ball, 10 ... pin, 12 ... contactor, 13 ... spring, 14 ... adjusting screw, 40 ... seating contact circuit, 42 ... one-shot circuit, 44 ... AND circuit.

Claims (1)

[Scope of utility model registration request] 1. A central member having a contact for contacting an object to be measured, a case having at least three seat portions for seating the central member, and a case for tiltably holding the central member, and each seat portion. First detecting means having a stress-sensitive element disposed therein and outputting a first detection signal based on a pressure applied through the central member, and formed on the stress-sensitive element of each seat portion. Second detection means for outputting a second detection signal when at least one seating contact opens due to the attitude displacement of the contact, and a first detection signal from the first detection means. When a second detection signal is output from the second detection means within a set time after the output of the first detection signal, an electric circuit that outputs a contact signal at the output time point of the first detection signal is provided. Contact detection device.