TOOL SETTING OR ANALYSIS DEVICE

• US 20100051783A1
• Filed: 05/02/2008
• Published: 03/04/2010
• Est. Priority Date: 05/02/2007
• Status: Active Grant

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw PLC
• Inventors: Merrifield, Benjamin Jason, Egglestone, Edward Benjamin, Marshall, Derek
• Granted Patent: US 8,530,823 B2
• Time in Patent Office: Days
• US Class Current: 250/206
• CPC Class Codes: B23Q 17/24 using optics or electromagnetic waves
• CPC Class Codes: B23Q 17/2485 using interruptions of light beams
• CPC Class Codes: H03K 17/941 using an optical detector H03K17/968 takes precedence
• CPC Class Codes: H03K 2217/94104 using a light barrier

Abstract

A tool setting or tool analysis device for a machine tool comprises a light source for producing a light beam. A light receiver receives the light beam and produces a signal indicative of the amount of light received. This is analyzed by a main analysis circuit to generate a trigger signal to a machine controller when the beam is at least partially occluded. To provide fail-safe operation should the main circuit not recognize the tool, a back-up trigger signal is produced after a delay by a delay circuit. In one preferred form, the back-up trigger signal may oscillate, providing repeated edges which can ensure fail-safe operation even if the machine controller suffers from a blind window and therefore misses the initial trigger signal.

Claims

1. A tool setting or tool analysis device comprising:

a light source for producing a light beam;

a light receiver for receiving the light beam and producing therefrom a signal indicative of the amount of light received;

a main analysis circuit for analysing the signal from the light receiver and generating a trigger signal when the beam is at least partially occluded;

a secondary trigger signal generating circuit which also receives the signal from the receiver, and which generates a back up trigger signal.

2. A tool setting or tool analysis device according to claim 1, wherein the secondary circuit generates the trigger signal if the signal from the receiver remains in a given state for longer than a predetermined time period.

3. A tool setting or tool analysis device according to claim 1, wherein the output of the secondary circuit is connected in parallel with the output of the main circuit.

4. A tool setting or tool analysis device according to claim 2, wherein the output of the secondary circuit is connected in parallel with the output of the main circuit.

5. A tool setting or tool analysis device according to claim 1, including an oscillator or oscillation generator, connected to provide an oscillating trigger signal.

6. A tool setting or tool analysis device according to claim 2, including an oscillator or oscillation generator associated with the secondary circuit, to cause repeated trigger outputs after the end of the predetermined time period.