JPH0369045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to workpiece inspection systems, and more particularly to techniques for using probes in automated machine tools to contact a workpiece and provide information about the workpiece.

Automated machine tools require sophisticated equipment to position the workpiece surface. One of the most common methods is to have a machine tool contact a probe with the workpiece and record the position of the probe when contact is made. This type of probe is designated as a contact probe. These probes generally include a projection for contacting the workpiece and a circuit operative to produce an electrical signal when the projection contacts a predetermined part. Information about the shape or position of the part can be calculated from the X, Y and Z axis position data of the probe when the probe produces an electrical signal.

One of the problems encountered in many uses of these types of inspection systems lies in the manner in which signals indicative of contact by the probe are sent back to the controller. This method is often impractical to rely on traditional wires to transmit signals because the wires can interfere with normal processing operations.

The patent literature discloses several probe configurations for use in automatic processing centers where the probe is temporarily stored in a tool magazine and is loaded and unloaded with respect to the spindle by an automatic tool change mechanism. Typical examples of patents disclosing these probes include U.S. Pat. No. 4,339,714 to Ellis, U.S. Pat.
Juengel, U.S. Patent Application No. 259,257, entitled "Apparatus for Detecting the Position of a Probe with respect to a Workpiece," filed on the 30th.

Kirkham's approach is disadvantageous because the radio frequency signal is susceptible to electromagnetic interference and must be used within a relatively short probe-to-receiver distance. A problem with the probe system of the Ellis patent is that the reactive coupling between them requires extreme care in aligning the probe with a specially constructed sensing device in the spindle head for proper operation. be. The infrared transmission approach disclosed in the Juengel patent cited above is far more advantageous. However, this also often requires the probe to have its own power supply.

It has also been suggested to use contact probes in turning centers, such as lathes, as well as in machining centers. Turning centers differ from machining or milling centers in that the workpiece is rotated instead of the tool. In most turning centers, tool holders are mounted at spaced locations around a turret that operates to selectively advance one of the tools relative to the workpiece for machining the workpiece. There is. Generally, tools for performing dimensional machining operations on the workpiece are housed in slots in the turret, while bore tools, such as boring bars, are held in adapters mounted to the turret.

Contact probes used in turning centers have a number of problems to overcome that are somewhat different from probes used in machining centers, although the method of transmitting probe signals back to the control equipment still maintains general interest. has. One problem specific to applications in turning centers is that the probe is fixed relative to the turret even when not in use, unlike the situation in machining centers, where the probe is inserted into the spindle only when needed to be used. It is to remain as it is.
As a result, the probe insertion operation cannot be relied upon to energize internal electronic circuits.

One conventional contact probe technique in turning centers is to use an inductive transfer module to send a probe signal through the turret to a controller. For example, Renishaw
See Electrical's LP2 probe system literature. Unfortunately, this technique requires substantial modification of the turret in order to use the system. As a result, this approach does not allow for easy use on existing machines without the expense and need for machine downtime to perform refurbishment work.

Also, less directly related to the present invention, Fougere U.S. Pat.
No. 3670243, Amsbury No. 4130941 and
There are prior art techniques for wireless transmission of dimensional measurement data, such as that disclosed in Juengel et al. No. 4,328,623.

The present invention provides a probe structure particularly for use in turning centers. In particular, the probe is designed to be used in place of tools such as boring bars and the like used for working on the inside diameter of workpieces, such as in turning centers. One end of the probe has a protrusion for contacting the workpiece, while the other end of the probe housing is in the form of a cylindrical section. This cylindrical part has the same configuration as the tool so that the probe can be mounted on the turret in the same manner as the tool.

In a preferred embodiment, the probe
The middle portion of the housing is conical and provides a perpendicular abutment surface adjacent the cylindrical end. This abutment surface can be used as a stop to quickly place the protrusion of the probe in a known location relative to the machine tool. The cylindrical end is hollow and adapted to receive a battery for providing power to circuitry within the probe housing. Preferably, the probe uses at least one optical element for emitting an optical signal related to the operating state of the probe and the contact state of the protrusion with the object. The optical element is also mounted on the inclined surface of the probe housing and serves to transmit infrared radiation to a receiving head that is connected to the equipment section of the machine.

In this way, the probe can be easily used without any modification of existing turning centers. The probe has all the necessary power supplies and circuitry to transmit information associated with contact of the protrusion with a workpiece or other object of detection. The shape of the probe housing provides substantial latitude in the mounting location of the receiving head while minimizing the number of optical transmission elements required.

These and various other advantages of the present invention will become apparent to those skilled in the art upon reviewing the following description and drawings.

SUMMARY FIG. 1 shows a typical lathe apparatus in simplified form employing various features of the inventive step described below. A numerically controlled turning center 10 is shown with a control 12 for automatically controlling turning operations on a workpiece 14 according to instructions programmed therein. The turning center 10 generally has a rotary chuck 16 having jaws 18 thereon for holding a workpiece 14. A plurality of tools 22-24 are attached to the turret 20 for performing operations on the inner diameter (ID) portion of the workpiece 14. As shown in FIG. Typically, this type of internal diameter tool has a long handle that is held in place on the turret 20 by adapters 26-28. According to the present invention, the workpiece insertion probe 30 is connected to the tools 22-24.
It is attached to the turret 20 in the same manner as. In this embodiment, probe 30 is attached to turret 20 by an adapter 32 that is the same as adapters 26-28.

As is well known in the art, the controller 12, among other things, rotates the turret 20 to place the required tool in the appropriate working position and then rotates the turret until the tool contacts the workpiece to perform the required machining operation. It acts to move 20. Meanwhile, the probe 30 is used for inspecting the workpiece 14.
In this embodiment, probe 30 is well known in the art as a contact probe that produces an output signal when a protrusion of the probe contacts the surface of a workpiece or other object. Appropriate separators, digitizers, etc. are used to provide signals to the controller 12 indicative of the position of the probe 30. As a result, when the signal from the probe 30 indicates the state of contact with the workpiece, the control unit 12 determines the size of the workpiece,
Useful information regarding its proper positioning within the chuck, etc. can be obtained.

(A. Flash-on Method) The probe 30 has its own battery power supply to supply energy to its signal transmission circuit. Unfortunately, batteries have a limited useful life. Therefore, there is a real need for some means of maintaining battery life as long as possible. This is particularly true for small probes used in turning centers. Small probes are also limited by the battery size they can be used with, making energy conservation very important.

One feature of the present invention is to provide two optical communications between probe 30 and flash/receive head 40. The head 40 has an interface 42
It is connected to the control unit 12 via. When controller 12 determines that it is time to use probe 30 for a sensing operation, it generates a signal on line 44 to interface 42, which in turn generates a control signal on line 46 to control head 40.
to transmit a certain optical signal to the probe 30. In a preferred embodiment, this optical signal is a strong flash of infrared transmission. This flash is detected by a suitable detection device 48 (see FIG. 2) in probe 30. This flash causes the detection device 48 to connect battery power to the probe transmission circuit. The probe 30 emits infrared rays of a certain frequency to the head 40 via light emitting diodes (LEDs) 50 to 54.
respond to the flash by transmitting to the flash. This infrared radiation is received by flash/receive head 40, which in turn provides a signal to controller 12 via interface 42 that probe 30 is operating properly and is ready to perform its test operation. .

Next, the control unit 12 advances the probe 30 until the protrusion 56 comes into contact with the workpiece 14. Probe 30 responds to protrusion contact by producing a change in the frequency of the infrared radiation transmitted by LEDs 50-54. This frequency change is detected by the interface 42 and sent to the control section 12. The workpiece inspection operation continues as necessary, with each protrusion contact causing the probe 30 to transmit infrared radiation of varying frequency to the flash/receive head 40.

Probe 30 includes a timing device that disconnects battery power from the transmission circuit after a predetermined period of time. This period begins when battery power is first applied to the circuit and is reset each time the protrusion contacts the workpiece. Thus, this period elapses after the discovery operation is completed and
Battery power is cut off from the transmission circuit. Therefore, battery power is used only during the expected period of use of the probe. Battery power is shut off whenever the probe is not in use, thus conserving energy and extending battery replacement intervals.

(B Contact charging method) Figure 3 shows another method for extending battery life. In this embodiment, battery power is first connected to the probe transmission circuit by contacting the protrusion 56 of the probe against a known reference surface 60. Reference plane 60 may be any fixed point inside machine 10 whose position is known to control 12 . Probe contact with surface 60 connects the battery to the probe transmission circuit and initiates transmission from LEDs 50-54 to flash/receive head 40. Fratshyu/
The receiving head 40' may also be equipped with an optical detection device 48, which may require an internal flash drive or probe 30'.
It is similar to the previous flash/receive head 40, except that it does not require a flash/receive head. Other than this, the two embodiments operate in substantially the same way.
After initial operation, the probe is moved into position for inspecting the workpiece 14, and the probe 30' transmits a frequency-changed signal to the flash/receive head' when projection contact is made.
After a predetermined period of time since the last protrusion contact, the battery is disconnected from the probe transmission circuit.

(Probe Structure) FIGS. 4 to 6 show the structure of the probe 30 in detail. The probe housing features a generally conically shaped intermediate portion 70 and a rearwardly projecting shank or cylindrical portion 72 of small cross-sectional diameter. In this embodiment, the cylindrical portion 72 has a length of approximately 108 mm (41/4 inches) and an outer diameter of approximately 36 mm (1.4 inches).
It is hollow and has dimensions of inches.

The outer dimensions of the cylindrical portion 72 are the same as those of the tools 22 to 2.
The dimensions are selected to approximately correspond to the dimensions of the body or handle of No. 4. As a result, the probe 30 can be used in place of one of the tools inside the turret 20 and is held in the adapter 32 as well.
As shown most clearly in FIG. 4, this is accomplished by sliding the cylindrical portion 72 into the pocket 74 of the adapter until the rear wall 76 of the housing portion 70 abuts the front surface 78 of the adapter 32. I can do it. This procedure allows the protrusion 5
6 ensures that the tips of the turrets 6 are spaced at known positions relative to the turret 20. As a result, the control unit 12 can be accurately placed at the position of the protrusion 56 during the probe testing operation. Of course, other conventional means for appropriately spacing the tips 56 of the projections may be used. For example, some machine tools use a set screw (not shown) or other means in the rear of pocket 74 to effect spacing adjustment of the protrusions.

The cylindrical portion 72 desirably serves the dual purpose of providing a battery area as well as providing an easily handled support member. The long cylindrical shape of section 72 allows the use of a long-life "cylindrical" battery, similar in shape to a typical flashlight, to energize the probe delivery circuit. Preferably, two "C" type lithium batteries 80,82 are used. A cylindrical battery can be used instead of a relatively small battery such as a button or disk type battery, providing the probe with a very long useful life at low cost.

Batteries 80, 82 are slid inside portion 72. Next, the spring loaded cap 84
is threaded onto the end of portion 72, and spring 86 forces biased terminal 88 against plate 90. The lower surface of plate 90 has a round conductive layer 92 . Board 90
The recess 94 on the inner surface of the wall surface 76 is inserted by the screw 96.
fixed inside. The insulated lead wire 98 is connected to the plate 9.
Electrical connection to the conductive layer 92 is made through a through hole plated with zero. The opposite end of lead wire 98 is connected to a circuit board 100 containing probe circuitry. An electrical overview of this circuit will be given in the text below. Circuit board 100 is generally circular in shape and has electrical components mounted on both sides thereof. circuit board 10
0 is a suitable fastener 10 passing through the isolation leg 104.
2 to the inside of the intermediate section 70. The board 100 also has a circuit board 100 located centrally through which the various leads can pass.
an opening 10 to facilitate connection to a suitable part of the
It has 6.

A photodetector device 48 and its associated subassemblies are mounted on the outer ramped surface 110 of the intermediate housing portion 70 . In this example, the photodetector 48 is
A PIN type diode such as part number DP104 available from Telefunken. The detection device 48 is
A slope 112 that fits into the milling hole and has a window portion
is held in place by the Between the slope 112 and the detection device 48 is a transparent plastic layer 114;
An infrared filter layer 116 and an O-ring 118 are inserted. Suitable fasteners 120 clamp all of these components into a subassembly mounted within the kneading hole. Lead wires from detection device 48 pass through opening 106 and are connected to appropriate locations on circuit board 100.

LEDs 50 - 54 are mounted adjacent detection device 48 . The LEDs 50-54 are configured to emit light signals in the infrared range, ie, not normally visible to the human eye.
For example, LEDs 50-54 may be part number OP290 available from TRW. put it here,
The configuration of the LEDs 50 to 54 and the detection device 48 is as follows:
Note that these, along with the configuration of the inclined probe surface to which it is mounted, combine to optimize several important advantages. for example,
By mounting the LEDs 50-54 against the probe's inclined surface 110, the infrared light emitted thereby is directed forward of the turret 20 at an angle that allows it to be easily detected at various positions on the flash/receive head 40. be directed. The structure of this probe allows the user to
54 and the detection device 48 are approximately flashed/
This allows the probe to be rotated into a position pointing towards the receiving head 40. Therefore, it is not necessary to mount the flash/receive head 40 in an absolute spatial position relative to the probe 30;
This provides great flexibility of the system in its use in different machine tool installations. This provides highly reliable optical communication between probe 30 and flash/receive head 40 while minimizing the number of light emitting elements within probe 30. By minimizing the number of light emitting elements, the energy drain from the battery is kept as small as possible, thereby further extending battery life.

Around the entire circumference of the assembly of the intermediate section 70, the wall surface 7
6 is attached to the rear portion of section 70 by suitable fasteners 122. An O-ring, such as ring 124, is preferably used to seal the interior of probe 30 from any adverse conditions that the probe may encounter during use in machine tool equipment.

The annular nosepiece 130 has male threads 132 that mate with threads formed in a bore 134 in the front face of the intermediate housing portion 70 . O-ring 136 is again used for sealing purposes. The nosepiece 130 can be of various lengths to increase or decrease the spacing between the tips 56 of the projections as desired. Due to the threaded engagement with the intermediate housing part 70, a variety of such nosepieces can be made and interchanged for different applications.

A switch device 140 is removably attached to the nosepiece 130. The switch device 140 is connected to the internal passage 14 of the nosepiece 130.
The surrounding O-ring 146 is an interference fit against 5.
It has a circular end structure 142 that includes. One or more locking screws 148 extending perpendicularly to the nosepiece 130 tighten the switch device 140 in place. Switch device 140 can be a variety of structures that act to open or break one or more electrical contacts when protrusion 56 is moved from its resting position. Those skilled in the art will be aware of a variety of structures that serve such general purposes. One suitable switch structure is disclosed in detail in commonly assigned U.S. patent application Ser. No. 388,187 to RFC Sacks, filed June 14, 1982. This patent application is mentioned in the text for reference. In summary, this structure uses a rocker plate with three equally spaced ball contacts. The kneading rocker plate is biased by a spring so that the balls are always pressed against the three corresponding current-carrying inserts. This inserter pair having three balls is the switch (in the following text,
The switches S1 to S3 function as switches S1 to S3, and are connected in series. This rocking plate has a protrusion 5
connected by 6. Whenever the protrusion 56 moves, the rocker plate tilts and lifts the ball contact from its corresponding inserter, thereby breaking the electrical connection therebetween.

The three switches in device 140 are connected to wire 1
50 to the circuit on board 100.
The other end of wire 150 has a small coaxial connector 152 or other suitable connector that mates with the connector on the end of replaceable switch device 140. Those skilled in the art will appreciate that these types of switch devices can be very sensitive and may require replacement. The structure of the present invention allows such exchanges to be made quickly and easily.

The probe 30 has protrusions of various shapes and dimensions.
can be used in connection with For example, instead of the straight protrusion 56 shown in the figures, a protrusion whose tip is deviated from the main longitudinal axis of the probe 30 could be used.
Various protrusions are interchangeable with switch device 140 and may be attached thereto through the use of suitable fasteners, such as set screws.

(Flash Loading Method) A. Flash/Receive Head The details of the mechanical structure of the flash/receive head 40 are most clearly shown in FIGS. 7-9. Flash/receive head 40 utilizes a generally rectangular container 160 having a detected opening in its front face 164. one or more circuit boards 16
6 is mounted within the container 160. circuit board 1
66 has various electrical components thereon for performing functions described in detail below.
The two most important components are shown in these figures. These elements are the xenon flash tube 16
8 and a photodetector 170. As mentioned above,
The purpose of flash tube 168 is to produce a short, intense pulse of light to initiate probe operation.
Xenon is desirable because it produces light that is rich in infrared radiation. In a preferred embodiment, flash tube 168
Part number BUB0641 available from Siemens
It is. This is approximately 50μ at a power of 100 watts/second.
A flash or light pulse lasting for seconds can be produced. Of course, other types of suitable light sources can also be used.

Although not absolutely necessary, it is desirable that the visible light produced by flash tube 168 be eliminated to avoid confusion for operators and other personnel in the work area where machine tool 10 is being used. For this purpose, an infrared filter 172 covering the aperture 162 is used. The infrared filter 172 blocks visible light but allows the infrared light generated by the flash tube 168 to pass therethrough.

On the other hand, the purpose of the photodetector 170 is to
The purpose is to detect the infrared rays transmitted by 0. In this embodiment, the photodetector 170 is
It is a PIN type diode and operates similarly to the detection device 48 in the probe 30. convex lens 174
The infrared rays from the probe 30 are transmitted through this lens 17.
Preferably, the aperture 162 is used to focus on the photodetector 170, which is located at the focal point of the photodetector 170. Rounding out the structure of flash/receive head 40 is a transparent faceplate 176. A face plate 176 covers the opening 162 and is suitably attached to the front portion 164 with a gasket 178 therebetween.

B Flash/Receive Head Circuit FIG. 10 shows the flash/receive head circuit of the preferred embodiment.
The circuitry used in the receiving head 40 is shown. As mentioned above, the head 40 has the reference number 46.
Connected to an interface 42 on one or more electrical wires shown generally at .

The 26 volt alternating current (AC) signal is connected to step-up transformer T1
is given to the primary side of Energy from transformer T1 is further stored in capacitors C8 and C9 connected across the positive and negative electrodes of xenon flash tube 168. In this example, capacitors C8 and C9 are approximately
Stores 250 to 300 volts DC.

To flash tube 168, controller 12 generates an appropriate signal level on the line labeled "CONTROL" via interface 42 to cause LED 1 to flash.
71 is made conductive to emit light. LED171
is part of a light-tight package that includes a silicon controlled rectifier (SCR) 173. SCR 173 is connected in a series circuit with the primary side of transformer T2 and capacitor C10. Capacitor C10 is connected to capacitor C8 and capacitor C9.
Similarly, it is charged due to the action of transformer T1.
When LED 171 is energized, SCR 173 becomes conductive, causing the primary side of transformer T2 to discharge the charge on capacitor C10. This charge is stepped up to approximately 4000 volts by transformer T2, the secondary of which is connected to trigger electrode 175 of flash tube 168. This trigger electrode 175 is capacitively coupled to tube 168, and its high voltage is sufficient to ignore gas within the tube. The ionized gas becomes sufficiently conductive to allow the energy from capacitors C8 and C9 to discharge between the positive and negative electrodes to produce a short period of very intense light flash. After tube 168 is flashed, the capacitor initiates a control signal that causes another flash to interface 42.
Start charging again until the given time.

The probe 30 is connected to the flash/receive head 40.
responds to the flash by transmitting an infrared signal that is picked up by a photodetection device 170 at. Photodetector 170 is connected to a tuned tank circuit consisting of variable inductor L1 and capacitor C2. In a particular case, the probe 30 operates at approximately 150KHz until the probe contacts contact the object, at which time the frequency changes to approximately 138KHz.
This results in pulsed infrared radiation at a frequency of . The tank circuit in the flash/receive head 40 is tuned to approximately the average of these two frequencies, so that the head circuit can detect either of these probe frequencies, but only at some preselected frequency. It will remove irrelevant frequencies that are out of band.

The remaining circuitry in FIG. 10 is used to amplify the detected signal transmitted from the probe 30 connected to the interface 42 on one output line. , uses a field effect transistor Q1 whose high input impedance matches that of the tuned circuit to avoid loading problems.Transistor Q2 cooperates with transistor Q1 to amplify the received signal and transfers it using transistor Q3. The amplified signal is connected to the interface 42 on the output line via a DC filter capacitor C6 and resistor R7 connected to the emitter of transistor Q3.

Interface 42 contains circuitry that operates to detect these selected probe signal frequencies and produces an output to controller 12 in response. A first signal is generated indicating that the probe is operating properly and a second signal is generated when the protrusion of the probe contacts an object. Suitable circuits for detecting frequency shifts are disclosed in Juengel, U.S. Pat. This patent application is incorporated herein by reference. In summary, such circuits use phase-locked loop circuits to perform frequency-shifting keying on a received signal; energizing the relay simultaneously with one detection; however, various other methods of detecting probe signals will be within the skill of one of ordinary skill in the art.

C Probe Circuit FIG. 11 is a wiring diagram of the circuit inside the probe 30. PNP transistor Q10 acts as a switch to selectively cut off power from batteries 80, 82 to the components used to generate infrared light from LEDs 50-54. Transistor Q10 is normally non-conducting, so batteries 80, 82 effectively monitor the open circuit to prevent energy from being drained from the batteries. However, when the flash/receive head 40 produces its infrared flash during the duration of the flash, the detection device 48 directs the current from the battery to the inductor L.
Let it flow to 10.

The very fast rise time associated with the light pulses from the xenon flash tube produces a unique light that is easily distinguishable from other light sources in the machine tool field. An infrared filter in the flash/receive head 40 filters out most of the visible light spectrum so that the flash is not visible and can cause irritation to nearby personnel. When the fast rise time light pulse reaches the detection device 48, it is converted into an electrical signal across the inductor coil L10. This coil L10 acts as a high pass filter, rejecting steady state or low frequency light pulses that would cause fluorescence in the region.

The current surge flowing through the detection device 48 during the flash is
This results in a "ringing" phenomenon in inductor L10, as is well known in the art. This ringing phenomenon is essentially a damped oscillation lasting about 500 μsec in response to a flash pulse of about 50 μsec. The vibrations from the inductor L10 are amplified and transferred to the inverting amplifier 2.
Inverted by 00. The output of amplifier 200 is connected to the base of transistor Q10. The instantaneous singing in inductor L10 caused by the flash of light creates a forward bias on both sides of the base/emitter junction of transistor Q10, causing it to conduct. The conduction state of transistor Q10 connects power from batteries 80, 82 to the input side of the circuit element designated +V in the drawing. When power is applied to the oscillator 202,
This oscillator begins providing pulses to timeout counter 204 . Counter 204 is reset to begin its timeout period when a flash is received from flash/receive head 40. This is accomplished by an inverter 206 which inverts the output of amplifier 202 to a positive signal that is shaped into a single pulse by the RC time constant of capacitor C20 and resistor R20. This pulse is
It is connected to the reset input of counter 204 via OR gate device 208. As will become clear below, whenever contact of the protrusion 56 of the probe with an object, represented by the opening of switches S1-S3, the timeout counter 204 is also reset.

The time-out counter 204 is connected to its output line 21 unless it is counting, that is, is not in a time-out state.
It is configured to provide a signal in a logically low state relative to 0. The logic low signal on line 210 is inverted by an inverter 212, which is further connected to the input of amplifier 200 via diode D20. As a result, the output of amplifier 200 is latched low, thereby maintaining transistor Q10 conductive and powering the circuit components until such time as counter 204 times out. counter 20
The expiration period at 4 is selected to be long enough to allow the control 12 to begin the actual inspection process with the probe in contact with the workpiece. Generally, a length of several minutes is sufficient for such purposes. The expiration period can be adjusted by potentiometer P20, which defines the oscillation frequency for time delay oscillator 202. Higher frequency oscillations from oscillator 202 will cause counter 204 to count faster, causing timeout to occur faster.
In the opposite case, the opposite is true. Of course, generating various time intervals is well within the abilities of those of ordinary skill in the art.

Carrier oscillator 220 and frequency divider 222 work together to define the frequency at which LEDs 50-54 transmit their infrared radiation back to flash/receive head 40. Until now, oscillator 220 has been the master
A crystal 224 with a known resonant frequency is used as a clock. Oscillator 220 clocks the oscillation state from crystal 224 to a conventional digital divider, such as frequency divider 222.
It acts to shape the pulse into a shape suitable for giving pulses. In this embodiment, the frequency divider 222
acts to divide the 1.8 MHz pulse from the carrier transmitter oscillator 220 by the number 12, thereby making the frequency of its output signal approximately 150 KHz. Frequency divider 22
The output of 2 is connected to a drive transistor Q12 or other suitable circuitry for energizing the LEDs 50-54 at a frequency defined by the output of the frequency divider. Thus, in this example, when flash/receive head 40 begins a flash injection sequence, probe 30 responds by beginning to transmit infrared radiation at a certain frequency. The probe delivery status is flash/
Detected by photodetection device 170 in receiving head 40, which also provides an indication to controller 12 that probe 30 is properly operating and ready to begin a detection sequence. If probe 30 does not respond in this manner, appropriate warning means may be used.

When the probe projection 56 contacts the object, one of the three switches S1-S3 of the probe device 140 is activated. An open condition of one of switches S1-S3 causes two things to occur. Firstly,
This condition resets the timeout counter 204 to the beginning of the timeout sequence. Second, this condition causes a shift in the frequency transmitted by LEDs 50-54. This can be done in various ways. However, in the preferred embodiment, an open condition of one of switches S1-S3 causes comparator 228 to go to a high condition. The output of comparator 228 is OR gate 2
08 to the reset input of the counter 204, thus resetting the counter. Additionally, the output of comparator 228 is connected to line 22.
Frequency shifting key (FSK) of frequency divider 222 on 9
is connected to the input side to cause it to divide the clock pulses from carrier oscillator 220 by a different number, thirteen in this example. The output signal from frequency divider 222 is thereby approximately
Shifted to 138KHz. For this reason, LED50~5
The frequency of the infrared radiation transmitted by 4 is shifted compared to the frequency transmitted when the probe is first deployed. This frequency shift is detected by photodetector 170 and transmitted to control 12 to indicate contact of the protrusion with the surface of the object, typically a workpiece. By knowing the position of the protrusion 56 when this signal is received, the control unit 12 can accurately calculate the dimensions of the workpiece or obtain other useful information.

Each time the probe responds with a shift in the infrared radiation transmitted therefrom, the controller 12 can move the probe 30 into contact with another workpiece surface. The expiry period of timeout counter 204 is selected to be longer than the period that elapses while the protrusions are in contact. When the detection operation is completed, the control unit 12 can proceed forward with other processing operations as needed. Since the energy from the battery is automatically shut off once the counter 204 times out, no further signal needs to be generated to shut off the probe. In such a case, its output line 210 will end up in a high state, connecting the base/base of transistor Q10.
This results in reverse biasing of the emitter junction. Therefore, transistor Q10 is placed in a non-conductive state. In this way, only the drains in the batteries 80 and 82 become the leakage current of the semiconductor and the photocurrent of the photodetector. Generally, this current can be very small, often less than 300 μamps.
As a result, components requiring more current are disconnected from the battery power supply until actually needed for anticipated use of the probe. These elements are preferably made in CMOS type semiconductor technology to further save drain on the battery during use.

In a non-limiting example, the carrier oscillator 2
20 is formed by a crystal controlled transistor element 2N2222, while the frequency divider 222 is a National
The oscillator 202 is a LM4526 available from National Semiconductor, and the oscillator 202 is formed from half of an LM2903 integrated circuit, also available from National Semiconductor.
Available from National Semiconductor
It is LM4040.

(Contact Loading Method) The contact loading method previously described in connection with FIG. 3 can be used as an alternative to the flash loading method described in Chap. Both approaches have the same common goal: extending battery life. The probe structures and circuitry for both of these approaches are strikingly similar. A schematic diagram of the probe circuit for the contact injection method is shown in FIG. This circuit is similar to that of FIG. 11, so that the same reference numbers are used to match common components.

Comparing the two figures above, the main difference is the lack of sensing device 48 and associated induction coil L10, due to resistor R50 and capacitor C50. This circuit also includes a line 231 connected between the probe switches S1-S3 and a node N1 connected to the input side of the inverting amplifier 200.
They differ in that they include Reference plane 6 of protrusion 56
0 (FIG. 3) results in switches S1 to S3.
until such time as one of the transistors Q1 opens.
0 is held non-conducting. This is because as long as switches S1-S3 are closed, ie, as long as the probe prongs are not touching anything, these switches maintain the input to amplifier 200 at approximately ground level. However, the protrusion 56
comes into contact with the reference surface 60, switches S1 to S3
One of them opens, causing capacitor C50 to begin charging. The values of resistors R50 and R18 and capacitor C50 are inverted by amplifier 200 before capacitor C50 connects to transistor C1.
Preferably, the RC time constant is selected to provide an RC time constant that delays the time it takes to charge up to a sufficient voltage to turn 0 ON. For this purpose, the control unit 12
requires that the probe protrusion 56 be pressed against the reference surface 60 for a certain period of time, for example about 1 second. This procedure will ensure that accidental bumps on the prongs of the probe or other extraneous factors such as electrical noise will not falsely trigger the probe.

Once capacitor C50 is sufficiently charged,
Transistor Q10 is turned on, and power is supplied from batteries 80 and 82 to the probe transmission elements. Counter 204 is reset and provides its output signal on line 210 to latch transistor Q10 conductive. In this embodiment, due to the tripping of the comparator 228 while the protrusion 56 of the probe is in contact with the reference surface, the frequency divider will initially occur at the lower of the two output frequencies. However, the control unit 12
can be suitably programmed to view this initial probe signal as an indication that the probe has been properly loaded and is ready to proceed to inspect the workpiece.

Assuming that the probe 30' is operating properly, the controller 12 then proceeds to the workpiece inspection step;
A protrusion 56 contacts the surface of the workpiece. Once the protrusion 56 moves away from the reference surface 60, the switch S1
~ S3 is closed and the frequency divider 222 is connected to the LED 50.
~54 is driven at another frequency. As soon as the protrusion comes into contact with the surface of the workpiece, switches S1 to S are activated.
3 opens again and trips comparator 228. As a result, the timeout counter 204
brings about a reset state. Comparator 228
The trip operation of
Send the output to 2 and send the output to
This produces a shift in the frequency of the outputs of the LEDs 50-54.
This procedure continues until such time as the workpiece inspection process is complete and battery power is automatically disconnected from the probe's circuitry once the timer 204 expires.

SUMMARY After reading the above description, it will be apparent to those skilled in the art that this text discloses several important improvements in the art of inspecting workpieces. Each embodiment has been described in connection with the best presently contemplated method for carrying out the inventive idea. However, no attempt has been made to list all alternatives or modifications to the general concept of the invention. Such modifications and improvements will become apparent to those skilled in the art upon consideration of the drawings, text, and appended claims. For example, it will be apparent that flash or contact loading methods can be performed using different types of probes than those shown herein. Therefore, while the invention has been described with respect to particular instances thereof, its true scope should be gauged in light of the following claims and equivalents thereof.

[Brief explanation of drawings]

FIG. 1 is a usage environment diagram showing a detection system provided according to the teachings of the present invention used in an automatic lathe, and FIG. 2 is a perspective view showing a detection system using a flash charging method according to an embodiment of the present invention. 3 is a perspective view illustrating a method of using a detection system using a contact injection method according to another embodiment, and FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 2 of a probe structure according to an embodiment of the present invention. , FIG. 5 is a cross-sectional view taken along line 5--5 in FIG. 4, FIG. 6 is an exploded perspective view of the probe shown in FIG. 4, and FIG. 7 is a cross-sectional view of the probe shown in FIG. 8 is a cross-sectional view taken along line 8--8 of FIG. 7; FIG. 9 is a top view of the circuit board used in the flash/receive head of FIG. 7; FIG.
Figure 11 is a schematic diagram of the circuit used in the flash/receiver head, Figure 11 is a schematic diagram of the circuit used in the probe of one embodiment of the invention using the flash input method, and Figure 12 is the contact input method. FIG. 1 is a schematic diagram of a circuit used in a probe using. 10...Turning center, 12...Control unit, 14
... Workpiece, 16 ... Rotating chuck, 18 ... Jaw, 20 ... Turret, 22 to 24 ... Tool,
26-28...adapter, 30...probe, 3
2...Adapter, 40...Flash/reception head, 42...Interface, 44, 46...
Line, 48...Photodetection device, 50...LED, 5
2...LED, 54...LED, 56...protrusion,
60...Reference surface, 70...Intermediate housing part,
72...Cylindrical portion, 74...Pocket, 76...
...Rear wall, 78...Front, 80, 82...Battery, 84...Cap, 86...Spring, 88...
Terminal, 90...Plate, 92...Conductive layer, 94
... recess, 96 ... screw, 98 ... lead wire, 1
00...Circuit board, 102...Fixing tool, 104...
Isolation leg, 106... Opening, 110... Inclined surface, 1
12...Slope, 114...Transparent plastic layer,
116... Infrared filter layer, 118... O ring, 120, 122... Fixture, 124... Ring, 130... Nose piece, 132... Male thread, 134... Inner hole, 136... O ring, 1
40... Switch device, 142... Hook-shaped end structure, 145... Passage, 146... O-ring, 1
50...Electric wire, 152...Coaxial connector, 160
... Rectangular container, 162 ... Opening, 164 ...
Front section, 166... Circuit board, 168... Xenon flash tube, 170... Photodetector, 171...
LED, 172...Infrared filter, 173...
SCR, 174... Convex lens, 175... Trigger electrode, 176... Transparent face plate, 200... Inverting amplifier, 201, 204... Time-out counter,
202... Oscillator, 206, 212... Inverter, 208... OR gate device, 210... Output line, 220... Carrier wave oscillator, 222... Frequency divider, 224... Crystal, 228... Comparator, 229, 231...Line.

Claims (1)

[Scope of Claims] 1. A contact probe for detecting contact with a workpiece, comprising: a protrusion projecting from one end thereof so as to come into contact with the workpiece; and a substantially conical convergence toward the protrusion. a housing having an intermediate portion having a shaped outer surface and an elongated hollow generally cylindrical portion, the intermediate portion having a rear wall at an end of a larger cross-sectional dimension remote from the protrusion; a rear wall extends generally perpendicular to the axis of the protrusion, the cylindrical portion having a reduced cross-sectional dimension relative to a maximum cross-sectional dimension of the intermediate portion and extending from the rear wall; The contact probe further includes: a circuit arrangement within the housing for generating a signal related to contact of the protrusion with the workpiece; and at least one battery in the cylindrical portion for powering the circuit arrangement. at least one optical transmitting device disposed on the converging outer surface of the intermediate portion of the housing for providing an optical signal associated with contact of the protrusion with the workpiece to a remote receiver. A contact probe characterized by: 2. The contact probe of claim 1, wherein the optical transmitter comprises an infrared transmitter operative to transmit infrared radiation. 3. The contact probe according to claim 1 or 2, wherein the hollow cylindrical portion includes a plurality of cylindrical batteries connected in series. 4. A contact according to claim 3, wherein the cylindrical part includes a removable cap at the end of the cylindrical part for allowing the battery to be slid into the interior of the cylindrical part. probe. 5. The circuit arrangement generates a predetermined frequency to drive the infrared transmitting device to indicate proper operating status of the contact probe, and shifts the frequency when the protrusion contacts the workpiece. The contact probe according to claim 2, characterized in that: 6. A photodetector mounted adjacent to the infrared transmitting device is further provided, and power from the battery is selectively coupled to the circuit device when a given optical signal is detected by the photodetector. The contact probe according to claim 5, characterized in that: 7. A switch device comprising: an annular nosepiece screwed onto one end of the intermediate portion of the housing; and a protrusion member inserted into the nosepiece and removably attached to the nosepiece; Claim 5 further comprising a cable connecting to the circuit device.
The contact probe according to item 6 or item 6. 8. One terminal of one battery is pressed against a conductive region on a member that closes away from one end of the cylindrical portion, and the conductive region is electrically connected to the circuit device. A contact probe according to any one of claims 4 to 8. 9. The contact probe according to claim 8, wherein the member is a circuit board attached to the rear wall. 10. The optical transmitting device is arranged in a sector of the middle part of the housing, the sector extending less than 180 degrees around the circumference of the middle part of the housing. The contact probe according to any one of the ranges 4 to 9.