Abstract: In a method and a device for determining a reference position of a locking part moved by an electric motor, the locking part is moved in the direction of the closed state thereof, until the same reaches a stop position. At that location the meter reading of a position meter describing the stop position is detected and buffered. Subsequently a movement of the locking part is carried out in the direction of the opened state thereof. The locking part is then moved again in the direction of the closed state thereof, until it again reaches a stop position. At that location a meter reading describing the stop position is detected, and compared to the buffered meter reading. If both meter readings agree, the first stop position is determined as the reference position. The method and device can be utilized, for example, for power window lifts and sunroofs of motor vehicles.

Abstract: A method for aligning a probe relative to a supporting substrate defining a first planar surface, an edge, and a first crystal plane includes the steps of masking the surface of the substrate to define an exposed area on the first surface at the edge; and etching, using an etch reagent, a recess in the exposed area, the recess defining first and second opposed sidewalls, an end wall remote from the edge, and a bottom wall. The method further includes the step of providing a probe substrate defining a second planar surface and a second crystal plane identical to the first crystal plane, and positioning the probe substrate so that the first and the second crystal planes are positioned identically when forming a probe from the probe substrate using the etch reagent, wherein the probe defines congruent surfaces to the first and second sidewalls.

Abstract: An apparatus for controlling the Z axis position of a wafer prober includes a first sensor unit including a plurality of pressure sensors distributed and installed between a Z axis support plate, for supporting a Z axis transferring unit and a Z axis base. Actuators are distributed and installed between the Z axis support plate and the Z axis base, and lift up or lower the Z axis support plate. A driving unit drives the actuators. A control module controls the driving unit to drive the actuators in response to pieces of sensed data. The control module drives the actuators when a difference between the pieces of sensed data is greater than a preset difference limit value, thus enabling the chuck plate to be maintained in a horizontal state.

Abstract: One embodiment of the present invention is a method for aligning a first workpiece to a second work piece that includes: (a) placing the first workpiece on an alignment apparatus including: (i) two or more fluid chambers disposed in fixed relation to each other, the chambers having a movable wall and one or more apertures for admitting or releasing fluid; (ii) fluid channels coupled to the one or more apertures that enable fluid to flow between at least two of the fluid chambers; and (iii) one or more valves disposed to enable or to stop the flow of fluid through one or more of the one or more fluid channels; (b) pumping incompressible fluid into the fluid chambers; (c) opening the one or more valves; (d) bringing the first and second workpieces into contact; (e) waiting a predetermined time for fluid flow in the fluid channels; (f) determining whether the first and second workpieces are aligned; (g) if they are aligned, shutting the valves; and (h) if they are not aligned, moving the second workpiece a prede

Abstract: Electronic devices may be tested using a test station with a test fixture. The test fixture may include a first holding structure in which a device under test may be placed and a second holding structure for supporting test probes. The second holding structure may be mated with a test probe alignment structure during test station setup operations. The test probe alignment structure may include registration features configured to set the relative position of the first and second holding structures to a known configuration and may include test probe alignment features that can be used to correctly position the placement of the test probes. If at least one of the test probes is not sufficiently aligned to its corresponding alignment feature, the test probe alignment structures will not be able to engage properly with the second holding structure, and the position of the problematic test probe may be adjusted accordingly.

Abstract: Apparatus (10) for transmission testing of a telecommunications jack (100) having a plurality of insulation displacement contacts (IDCs) (103), the apparatus (10) including: a base (30); a plurality of transmission test probes (31) associated with the base (30); and a jack holder (20) for removably coupling the jack (100) to the base (30) such that IDCs (103) of the jack (100) are in electrical communication with corresponding test probes (31); wherein the jack holder (20) is fixed relative to the base (30) during testing, such that the jack (100) remains stationary with respect to the probes (31).

Abstract: Disclosed is an improved probe having a spring portion which allows effective contact with a device under test without requiring a lower die portion. The probe includes a slot retention and placement portion, which provides for an improved approach for manufacturing arrangements of probes, where the slot retention and placement portions of the probe facilitate precise placement and alignment of the probes while not excessively increasing the cost or complexity of the probes and probe cards.

Abstract: Electronic components on a substrate may be shielded using electromagnetic shielding structures. Insulating materials may be used to provide structural support and to help prevent electrical shorting between conductive materials and the components. The shielding structures may include compartments formed using metal fences that surround selected components or by injection molding plastic. The shielding structures may be formed using metal foil wrapped over the components and the substrate. Electronic components may be tested using test posts or traces to identify components that are faulty. The test posts or traces may be deposited on the substrate and may be used to convey test signals between test equipment and the components. After successful testing, the test posts may be permanently shielded. Alternatively, temporary shielding structures may be used to allow testing of individual components before an electronic device is fully assembled.

Abstract: An assembly includes a lower guide plate having a first plurality of through-holes therein, and an upper guide plate over the lower guide plate. The upper guide plate includes a second plurality of through-holes therein. The assembly further includes a plurality of probe pins. Each of the probe pins is inserted through one of the first plurality of through-holes and one of the second plurality of through-holes. The assembly further includes a plurality of probe pin stoppers, each attached to one of the probe pins, wherein the plurality of probe pin stoppers has lateral sizes greater than lateral sizes of the second plurality of through-holes. The plurality of probe pin stoppers is located over the upper guide plate.

Abstract: To eliminate or otherwise reduce unintended movement of a probe tip of a probe assembly being held by a probe arm, the probe assembly includes one or more resilient members that compensate for the contraction or expansion of the probe arm in accordance with the coefficient of thermal expansion of the material from which the probe arm is made. Thus, the probe tip can remain in contact with a sample being measured at the desired location on the sample, during an automated full or wide scale temperature range sweep.

Abstract: Recesses are formed on one surface of a substrate. A conductive film covers an inner surface of each of the recesses. This conductive film contacts a bump of a semiconductor device to be inspected and is electrically connected to the bump. It is therefore possible to prevent damages of the bump to be caused by contact of a probe pin.

Abstract: A device for panel reliability testing and method thereof are proposed. The device includes a connection module, for connecting the panel and an aging module; a reliability chamber control module for sending a voltage regulation command to a bias module and/or a switch control command to the aging module; the bias module, for regulating voltage and transmitting information about voltage regulation to the aging module; and the aging module, for performing an aging operation on the panel depending on the switch control command sent from the reliability chamber control module and the information about voltage regulation transmitted from the bias module. Compared with the prior art, LCD panels undergo the aging testing before being packaged, thereby shortening a time period of manufacturing LCD panels and enhancing production efficiency.

Abstract: Devices and methods useful for testing bare and packaged semiconductor dice are provided. As integrated circuit chips become smaller and increasingly complex, the interface presented by a chip for connectivity with power supplies and other components of the system into which it is integrated similarly becomes smaller and more complex. Embodiments of the invention provide micron-scale accuracy alignment capabilities for fine pitch device first level interconnect areas. Embodiments of the invention employ air-bearings to effectuate the movement and alignment of a device under test with a testing interface. Additionally, testing interfaces comprising membranes supported by thermal fluids are provided.

Abstract: Disclosed is a pre-alignment method and a computer-readable medium storing a pre-alignment program capable of reducing pre-alignment time and transfer time of a semiconductor wafer.

Abstract: A system separating defective dies from a wafer comprises a film frame platform and a pick-and-place device. The film frame platform comprises a support table assembly configured for supporting a film frame assembly and a platform surface configured to receive the placement of bins thereupon. The pick-and-place device is configured for moving in a linear manner between the support table assembly and the platform surface.

Abstract: A probe card assembly used to test electronic devices in an automated test equipment system. The probe card assembly includes a substrate having a plurality of through-holes contained therein and a plurality of electrical contact elements. Each of the plurality of electrical contact elements has characteristics of both a torsional beam and a cantilever beam design and is configured to scrub a test pad associated with the electronic device in two directions concurrently. The plurality of electrical contacts is configured to be magnetically aligned to the substrate. Each of the plurality of electrical contact elements is further configured to be removably adhered to the substrate thus allowing easy field replacement of individual electrical contact elements.

Abstract: A probe system includes a plurality of spaced apart height-variable legs, each of which is composed of a stack of blocks magnetically attached to each other, a platen bridging and magnetically secured to the legs, and a probe positioner magnetically attached to the platen. The probe positioner includes an xyz-axes position adjuster mounted on the platen and connected to a first link, a first ball joint interconnecting the first link and a second link, a rotary connector interconnecting the second link and a third link, and a second ball joint connecting the third link to a chuck unit for holding a probe.

Abstract: A capacitor test fixture for positioning capacitors under test includes a main body, a clamping section, an operating section, and a cover. The main body defines an opening, a plurality of receiving slots at the bottom of the opening to receive the capacitors, some positioning slots located at opposite sides of the opening, and a sliding slot. The clamping section includes a first hook, and the operating section includes a second hook corresponding to the first hook. The cover locates and fixes the clamping section and the operating section to the main body. The operating section functions when the second hook holds back the first hook, the capacitors under test are received within the receiving slots, and when the second hook releases the first hook, the clamping section secures and makes contact with the capacitors for testing.

Abstract: A docking drive for a testing head comprising a plurality of locking mechanisms (10) each provided with an own locking drive (14, 21-28) comprises a synchronizing device (11, 12, 13) synchronizing the locking drives (14, 21-28) of the locking mechanisms (10). It may comprise a respective trapping device (15a, b) provided in a plurality of locking mechanisms (10) each retaining a locking element (50) to be locked in the respective locking mechanism (10) in a certain position. A locking element (50) of a docking system comprises a base (51), a locking section (55) and a connecting mechanism (52-54) provided between the base (51) and the locking section (55) and being manually releasable without tools. The locking section (55) may be resiliently supported opposite of the base (51). The locking element may comprise a first retaining section (56) for the trapping device (15) and a second retaining section (57) for a locking device (16).

Abstract: An inspection apparatus includes a mounting table movable in X and Y directions and an alignment mechanism which performs an alignment of a target object placed on the mounting table. Further, the alignment mechanism includes an image pickup device which is movable in either one of the X and Y directions and is capable of being stopped at a desired position and a controller for performing a preliminary alignment of the target object by moving the image pickup device and the mounting table in respectively movable directions.

Abstract: An alignment system for aligning one or more devices under test with respect to a test station includes a carrier that is configured to carry the one or more devices under test, a conveyor that is configured to move the carrier in unison with the conveyor, and an alignment structure. The alignment structure is engageable with the carrier to move the carrier with respect to the conveyor to align at least one of the devices under test with respect to the test station.

Abstract: A probe resistance measuring method includes measuring first resistances at three or more nodes by making contact at least a part of a plurality of probes of a probe unit with three or more pads for resistance measurement based on a first correspondence relation. The measured resistances are stored as a first measurement result and contact resistances of the plurality of probes of the probe unit are calculated based on the first measurement result.

Abstract: A probe card detecting apparatus includes a probe detecting chamber having a supporting body, a probe card positioned and mounted detachably via a first holder on the predetermined position of the supporting body, a first imaging device movably provided in the probe detecting chamber to detect needle tips of at least two probes of the probe card, a probe correction card positioned and mounted detachably via a second holder to the predetermined position of the supporting body, and a control device. Under the control of the control device, using the first imaging device, a difference between a horizontal position of needle tips of at least two probes and a horizontal position of at least two targets is detected as a correction value for performing a position alignment of the at least two probes with the at least two electrode pads of said semiconductor wafer.

Abstract: A system for probing with electrical test signals on an integrated circuit specimen in the external multidimensional magnetic field of controlled strength and orientation is provided by utilizing an assembly of cone-shaped electromagnets. In one form the system has an environmental enclosure and environmental control system for testing of an integrated circuit specimen at environmentally controlled conditions. The system of the present invention can be used for probing of electronic and spintronic devices.

Abstract: A probe card positioning mechanism in which, when a probe card used to inspect electrical characteristics of an object to be processed is detachably inserted in a head plate of an inspection apparatus or an insert ring fixed to the head plate, at least three positioning pins placed circumferentially with an interval therebetween on an outer circumference of the probe card are inserted in at least three corresponding positioning long holes formed in the head plate or the insert ring such that the probe card is positioned at a specified position of the head plate or the insert ring, wherein the positioning holes are formed as long holes being elongated in a width-wise direction of the probe card and the entire inner circumferential surface of the long holes is configured as a taper surface which is gradually declined along an insertion direction of the pins.

Abstract: A semiconductor wafer resting on a contact element has a spatially distributed force applied to its frontside and an equal and opposing force applied to its backside. The contact element comprises a solid immersion lens (SIL), and has an area less than the area of the wafer, but no less than the larger of the area of an optical collection area and an electrical probe assembly. The equal and opposing forces cause the wafer to conform to the shape of the contact element. Measurements, including electrical testing, optical probing and wafer characterization are performed on the wafer.

Abstract: Various apparatus and methods of testing a semiconductor chip for soft defects are disclosed. In one aspect, a method of testing a semiconductor chip that has a surface and plural circuit structures positioned beneath the surface is provided. An irradiation mask directs light or heat to a series of fractional portions of the surface to perturb portions of the plural circuit structures. The irradiation mask is adjustable such that at least one of the exposed series of fractional portions is smaller than another of the series of fractional portions. The semiconductor chip undergoes a test pattern during the irradiation to each of the fractional portions to determine if a soft defect exists in any of the series of fractional portions. Multiple paths can be tested simultaneously to inform subsequent individual CTP path tests.

Abstract: A probe head assembly for testing a device under test includes a plurality of test probes and a probe head structure. The probe head structure includes a guide plate and a template and supports a plurality of test probes that each includes a tip portion with a tip end for making electrical contact with a device under test, a curved compliant body portion and a tail portion with a tail end for making electrical contact with the space transformer. Embodiments of the invention include offsetting the position of the tail portions of the test probes with respect to the tip portions of the test probes so that the tip portions of the test probes are biased within the apertures of the guide plate, using hard stop features to help maintain the position of the test probes with respect to the guide plate and probe ramp features to improve scrubbing behavior.

Abstract: An electrical testing apparatus for testing an electrical test sample. The apparatus includes a conductor substrate (12) which is electrically connected via a contact spacing converter (7) to a test head (2). The conductor substrate is mechanically connected to a first stiffening device (26) and is thereby stiffened. At least one spacer (30) which penetrates the conductor substrate (12) is mechanically connected to the contact spacing converter (7) and is held on the first stiffening device (26) via at least one tilt adjusting arrangement (34).

Abstract: A manipulator system comprising a column unit and a carriage supported by the column unit and configured to move along a desired axis of translation. A marker is provided on the column unit along the axis of translation. A sensor is associated with the carriage and configured to sense a position along the marker. A position display unit is configured to receive a position signal from the sensor and display a current position of the carriage along the axis of translation. In another aspect, the column unit defines at least one slot. A lock assembly is attached to the carriage and includes a tang axially moveable between an unlocked position wherein the tang is disengaged from the at least one slot and a locked position wherein the tang is engaged in the at least one slot.

Abstract: There is provided a testing apparatus including a plurality of test units, a storage that is shared by the plurality of test units, where the storage stores therein wafers under test to be tested by the plurality of test units, a transport mechanism that transports the wafers under test between the storage and each of the plurality of test units, a mainframe that specifies a test procedure for each of the plurality of test units, a power source that is shared by the plurality of test units, where the power source supplies power to each of the plurality of test units, and a pressure source that is shared by the plurality of test units, where the pressure source supplies a pressure to each of the plurality of test units.

Abstract: A test device for testing a circuit board includes a base, a conveying platform, a driving unit, a connecting element, and a testing unit. The base has an operating space from above. The conveying platform is hinged to the base at a variable gradient, communicates with the operating space, and has thereon a carrier movable toward or away from the operating space as needed and configured to carry the circuit board. The driving unit is connected to the conveying platform and configured to drive the carrier to move. The connecting unit is connected to the conveying platform and the driving unit. The gradient of the conveying platform varies when the driving unit drives the carrier to move and thereby moves the connecting unit. The testing unit is movably disposed at the base and has at least one test terminal capable of approaching the operating space and testing the circuit board.

Abstract: By examining scrub mark properties (such as position and size) directly, the performance of a wafer probing process may be evaluated. Scrub mark images are captured, image data measured, and detailed information about the process is extracted through analysis. The information may then be used to troubleshoot, improve, and monitor the probing process.

Abstract: Systems and methods for deciding whether or not to indicate misalignment. In some examples, an analysis of parametric data relating to tests sensitive to misalignment is performed in order to determine which data is incongruous and to identify corresponding probes or socket contacts as suspected misaligned. In some examples, additionally or alternatively, a spatial analysis quantifies the placement of a set of identified suspected misaligned probes, which were identified from pass/fail test data and/or parametric test data, with respect to a contiguous or non-contiguous area on one or more wafers.

Abstract: The present invention relates to an apparatus for testing of back-contact solar cells. In one embodiment, the apparatus includes a support plate having vacuum holes with suction cups partially within the holes and probe pins within the suction cups. A solar cell is placed into contact with the suction cups and vacuum forces are applied through the suction cups to force contact pads of the solar cell against the probe pins. In another embodiment, the apparatus includes a support plate having probe pin holes with hollow probe pins located therein. Vacuum forces are applied through the hollow probe pins to force contact pads of the solar cell against the probe pins. The support plate in either embodiment may be an end effector of a robot used to pick up the solar cell and hold the front surface of the solar cell adjacent a light source while performing light induced testing.

Abstract: A probing apparatus for testing semiconductor devices comprises a housing configured to define a testing chamber, a device carrier positioned in the housing and configured to receive the semiconductor device, a platen positioned on the housing, an alignment module positioned on the platen, a planarity-adjusting module positioned on the alignment module, an angular adjusting module positioned on the planarity-adjusting module, and a card holder positioned on the angular adjusting module and configured to receive a probe card having a plurality of probes.

Abstract: A method of performing alignment of an array of probe tips of a probe card to corresponding contact pads for wafer probing applications by performing the steps of: obtaining a backside image of the wafer; overlaying a mapping of the contact pads over the backside image; selecting contact pads as landing points; obtaining an image of the probe tips array; comparing the landing points to corresponding positions of probe tips; and, if the positions of probe tips are not aligned with the landing point, rotating the probe card to align the positions of probe tips to the landing points.

Abstract: A handling device for positioning a test head, in particular at a test station, is provided with a positioning means enabling the test head to be positioned with respect to three dimensions. The handling device also has a mounting on which the test head can be attached and which is connected to the positioning means. The handling device is also provided with a fastening plate which is movably mounted and a compliance module by means of which the fastening plate can be moved between a starting position (I) and an end position (II, III) against the effect of a return force. The compliance module includes a housing, a spindle, a first sliding bushing and a second sliding bushing which are arranged in a movable manner on the spindle between a first stop and a second stop, and a spring element arranged between the sliding bushings and which impinges on the sliding bushings. The sliding bushings are movable relative to the housing. The compliance module permits bi-directional compliance of the test head.

Abstract: A test handler and method for operating a test handler for testing semiconductor devices are provided. The test handler includes a test tray located on one side of an opening apparatus in which a plurality of inserts are arrayed, wherein each insert comprises at least one semiconductor device loaded thereon, at least one opening unit for opening inserts at one part of the one side of the test tray, and a position changing apparatus comprises a motor including a driving pulley for moving at least one opening unit along a contact surface of the test tray such that the at least one opening unit changes positions on the test tray and is located at another part of the one side of the test tray in order to open inserts at the other part of the one side of the test tray.

Abstract: A semiconductor test device and method for sequentially carrying out tests including an AC test, DC test, and thermal resistance test on a power semiconductor device are provided. The semiconductor test device includes a holding unit that positions the power semiconductor device. Test units each generate a test signal for the power semiconductor device and determine a test result generated in response to the test signal. A connection unit switches between the test units and selectively connects the test units electrically to electrodes of the power semiconductor device. The connection unit is controlled such that the test units are sequentially connected to the power semiconductor device to perform a plurality of the tests. The connection unit may include parallel plate electrodes in proximity to each other across an insulating sheet. The parallel plate electrodes may connect the power semiconductor device to positive and negative power sources of the test unit.

Abstract: A position alignment of a transfer point of a transfer arm is performed by using a position detecting wafer capable of being loaded into an apparatus having a thin transfer port. The position detecting wafer S includes an electrostatic capacitance detecting sensor 50 for detecting an electrostatic capacitance in relation with a reference object for the position alignment. The electrostatic capacitance detecting sensor 50 includes a plurality of electrostatic capacitance detecting electrodes 52, each forming the electrostatic capacitance in relation with the reference object; and a control circuit 51 for controlling a detection of the electrostatic capacitance by each electrostatic capacitance detecting electrode 52, while communicating with each electrostatic capacitance detecting electrode 52. The electrostatic capacitance detecting electrodes 52 are provided on a rear surface of the position detecting wafer S, and the control circuit 51 is provided on a front surface of the position detecting wafer S.

Abstract: A method of aligning a wafer includes recognizing images of the wafer accommodated on a work table and a notch of the wafer using a camera, designating at least one notch point of the notch in a recognized image, producing at least one reference line using the designated notch point in the recognized image, designating a center point of the reference line in the recognized image, producing an imaginary line having an angle with respect to the reference line from the center point of the reference line in the recognized image, producing a center line of the wafer using the imaginary line in the recognized image, and aligning the wafer using an alignment apparatus to allow the center line of the wafer and an alignment line of the work table to be matched.

Abstract: A test unit to be used with a tester that tests an electrical characteristic of a circuit formed in a wafer includes a tester a board electrically connected to the tester; a first wireless port mounted on a lower surface of the tester board and electrically connected to the tester; a probe board that includes a probe to be in contact with an electrode pad of the electronic circuit, and is configured so that the probe board may be transferred along with the wafer into the system box while the probe and the electrode pad are in contact with each other; a second wireless port that is mounted on an upper surface of the probe board and electrically connected to the probe, and carries out contactless transmission/reception with the first wireless port; a chuck plate that is away from the tester board, and holds the probe board and the wafer; and a flexible expandable chamber that may be inflated by introducing gas thereinto.

Abstract: A universal test socket includes a housing frame including a side wall, an inner protruding portion protruding inwardly from the side wall, and a through window formed at a center portion of the housing frame, wherein the through window is surrounded by the side wall, a pin plate assembly coupled to the housing frame and including a pin plate in which a plurality of test pins are arranged and a plurality of guide pins formed on periphery of the pin plate, and a package guide portion coupled to the housing frame and located above the pin plate assembly, a semiconductor package to be tested being mounted on the package guide portion. When the pin plate assembly is coupled to the housing frame, the positions of the test pins arranged in the housing frame are varied according to a rotation angle of the pin plate assembly with respect to the housing frame.

Abstract: A sensing structure for use in testing integrated circuits on a substrate. The sensing structure includes at least two sensing regions connectable to a probe and at least one first sensing element. Each of the at least one first sensing elements is directly connected to two sensing regions such that for each sensing region a different value of an electrical parameter is measurable between the sensing region and a first reference potential so as to reliably determine a drift direction of a probe.

Abstract: A test assembly that may provide access to signals of a circuit that includes an integrated circuit. The test assembly may include structural members that limit movement of components relative to each other.

Abstract: A wafer inspection interface IF comprises a probe card, an adsorption unit configured to adsorb a wafer to the probe card, a wafer adsorption sealing member to which the probe card is adsorbed, and a fixing ring configured to fix the wafer adsorption sealing member to a card holder. The adsorption unit includes an air exhaustion unit, a first air duct whose right end portion is opened in the hermetically closed space and the left end portion is opened at a side of the fixing ring, a second air duct whose right end portion is opened to face an opening of the left end portion of the first air duct and the left end portion is opened to be connected with the air exhaustion unit, and a hole by which the first air duct is in communication with the second air duct.

Abstract: A locater tool for positioning a support device for supporting a test probe head or a test probe tip, the locater tool including a template, means for indicating a support device position associated with the template, and means for indicating an achievable probing zone on a surface having connection points when the support device is in the support device position. The locater tool may be a device-attachable locater tool or a pre-positioning locater tool.

Abstract: A probe apparatus includes a movable mounting table for supporting an object to be tested; a probe card disposed above the mounting table and having a plurality of probes to come into contact with electrodes of the object; a support body for supporting the probe card; and a control unit for controlling the mounting table. Electrical characteristics of the object are tested based on a signal from a tester by bringing the object and the probes into electrical contact with each other by overdriving the mounting table in a state where a test head is electrically connected with the probe card by a predetermined load. Further, one or more distance measuring devices for measuring a current overdriving amount of the mounting table are provided at one or more locations of the test head or the probe card.

Abstract: An exemplary manipulator of a robot includes a fastening seat defining two guiding grooves, a driving mechanism disposed on the fastening seat, two transmitting plates respectively received in the two guiding grooves and cooperating with the driving mechanism, and two detecting bars each fixedly connecting with a corresponding transmitting plate. A detecting pin is fixed on each of the detecting bars. Under a driving action of the driving mechanism on the transmitting plates, the transmitting plates are activated to slide in the guiding grooves to cause the detecting bars to move close to or apart from each other, whereby a distance between the two detecting pins is automatically regulated.