Keyboard testing apparatus

A keyboard testing apparatus includes a housing inside which two clamping members spaced from each other at an adjustable distance for receiving a keyboard to be tested therebetween. A retaining device includes a pneumatic cylinder for applying force to the keyboard for firmly retaining the keyboard in position. An indicator testing device includes several optic sensors for detecting light emitted from indicators of the keyboard. A key testing device includes several key actuators capable to sequentially actuate/de-actuate the keys of the keyboard. A conveying device drives the key actuators relative to the keyboard in order to position the key actuators with respect to each key of the keyboard. A control unit, preferably a processor-based device, controls the operation of the key testing apparatus and receives test signals from the keyboard and the optic sensors to determine if the keyboard function normally. The control unit generates a warning signal via a warning device when the keyboard is abnormal. The control unit also stores information of the test result for further processing.

FIELD OF THE INVENTION
 The present invention generally relates to a keyboard testing apparatus,
 and in particular to an apparatus for automatically testing indicators and
 keys of a keyboard.
 BACKGROUND OF THE INVENTION
 Keyboards have been widely used to serve as a man-machine interface between
 a user and an electronic apparatus, such as personal computer, industrial
 controller, and cash registers. An incorrectly-operating keyboard may lead
 to incorrect data input and thus cause serious damage to the electronic
 apparatus.
 Conventionally, a keyboard is tested manually by sequentially depressing
 the keys thereof by an operator. This is very inefficient. Furthermore,
 since the keys are manually depressed for test, the force that the
 operator applies to different keys may be different which may result in
 incorrect test result.
 It is thus desirable to have a keyboard testing apparatus that efficiently
 and effectively tests a keyboard in order to overcome the above problems.
 SUMMARY OF THE INVENTION
 Accordingly, an object of the present invention is to provide a keyboard
 testing apparatus, which automatically and sequentially test keys and
 indicators a keyboard whereby the keyboard is efficiently and effectively
 tested.
 Another object of the present invention is to provide a keyboard testing
 apparatus, which applies substantially the same force to all the keys of
 the keyboard for testing the keys thereby reducing the likelihood of
 incorrect test result.
 A further object of the present invention is to provide a keyboard testing
 apparatus wherein the force applied to keys of a keyboard for test can be
 precisely controlled.
 To achieve the above objects, in accordance with the present invention,
 there is provided a keyboard testing apparatus comprising a housing inside
 which two clamping members spaced from each other at an adjustable
 distance for receiving a keyboard to be tested therebetween. A retaining
 device includes a pneumatic cylinder for applying force to the keyboard to
 firmly retain the keyboard in position. An indicator testing device
 includes several optic sensors for detecting light emitted from indicators
 of the keyboard. A key testing device includes several key actuators
 capable to sequentially actuate/de-actuate the keys of the keyboard. A
 conveying device moves the key actuators relative to the keyboard in order
 to position the key actuators with respect to each key of the keyboard. A
 control unit, preferably a processor-based device, controls the operation
 of the key testing apparatus and receives test signals from the keyboard
 and the optic sensors to determine if the keyboard function normally. The
 control unit generates a warning signal via a warning device when the
 keyboard is abnormal. The control unit also stores information of the test
 result for further processing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 With reference to the drawings and in particular to FIGS. 1-3, wherein a
 keyboard testing apparatus constructed in accordance with the present
 invention, generally designated by reference numeral 100, is shown, the
 keyboard testing apparatus 100 comprises a housing 10 substantially
 enclosing the apparatus 100. The housing 10 defines an interior space
 therein surrounded by walls thereof At least an opening is defined in at
 least one wall for accessing the interior space. A rail 12 is disposed in
 the interior space and fixed on a bottom wall of the housing 10. Two
 clamping members 20, 21 are releasably mounted on the rail 12 by means of
 bolts A. The clamping members 20, 21 are spaced from each other to
 accommodate a keyboard-to-be-tested B (FIG. 5) therein with the clamping
 members 20, 21 engaging with and thus retaining the keyboard 200
 therebetween. The clamping members 20, 21 are movable along the rail 12 to
 adjust the space therebetween for accommodating keyboards of different
 sizes. Thus the keyboard testing apparatus 100 of the present invention
 may be used with keyboards of different sizes and different
 specifications. An example of the keyboard B is shown in FIG. 6.
 The keyboard testing apparatus 100 comprises at least a retaining device 30
 which may be of any suitable form. In accordance with a preferred
 embodiment of the present invention, the retaining device 30 comprises a
 pneumatic actuation system, such as a pneumatic cylinder, mounted on a
 guide rail 30' fixed to the housing 10. In the embodiment illustrated, the
 guide rail 12 is L-shaped having a vertical section and a horizontal
 section with the pneumatic cylinder movable along the horizontal section
 for accommodating keyboards B of different sizes. The retaining device 30
 comprises a movable shaft 31 to which a retaining member 32 is fixed. The
 movable shaft 31 is moved by the retaining device 30 to bring the
 retaining member 32 toward and into contact with the keyboard B retained
 between the clamping members 20, 21 thereby firmly securing the keyboard B
 in position.
 Also referring to FIG. 3, the keyboard testing apparatus 100 comprises an
 indicator testing device 40 which is arranged at a suitable position
 between the clamping members 20, 21. The indicator testing device 40
 comprises at least one optic sensor 41 for detecting light emitted from at
 least one indicator B1 of the keyboard B and generates an indicator test
 signal. Preferably, the indicator testing device 40 comprises a plurality
 of optic sensors 41 respectively corresponding to a number of indicators
 B1 of the keyboard B. In the embodiment illustrated, the indicator testing
 device 40 comprises three sensors 41 for detecting light emitted from
 three indicators B1 of the keyboard B. The number, position and
 arrangement of the optic sensors 41 may be changed in accordance with the
 indicators 41 of a particular keyboard to be tested.
 A switch or detecting element 42, such as a photo-electrical switch, a
 proximity switch and a micro-switch, is positioned whereby the switch 42
 is triggered when a keyboard B is positioned between the clamping members
 20, 21 whereby the indicator testing device 40 is actuated by the switch
 42. This effectively prevents an incorrect detection caused by
 environmental light. In accordance with an embodiment of the present
 invention, the switch 42 is also used to control the retaining device 30
 whereby only when a keyboard B is positioned between the clamping members
 20, 21 which triggers the switch 42, is the retaining device 30 actuated.
 Referring to FIG. 4, a key testing device 50 comprises a number of key
 actuators 51 which may be of any suitable form. In the preferred
 embodiment illustrated, the key actuators 51 comprise pneumatic cylinders
 each having a shaft 511 movable by the corresponding pneumatic cylinder to
 expand/withdraw. The shaft 511 has a contact element 513 mounted on a free
 end thereof to be moved thereby for contacting and thus actuating a key B2
 of the keyboard B. The shaft 511 is pre-loaded by a spring 512 which
 controls the force applied to the key B2 by the key actuator 51. In the
 embodiment illustrated, a block 514 is releasably fixed on the shaft 511
 and spaced from the contact element 513 to receive the spring 512
 therebetween.
 The block 514 is fixed to a support member 52. The support member 52 may be
 of any configuration and is L-shaped in the embodiment illustrated
 comprising a vertical section 521 and a horizontal section 523. The
 vertical section 521 defines a vertical elongate slot 522 movably
 receiving a bolt A and an associated washer C. The bolt A engages with an
 inner-threaded hole 516 defined in the block 514 thereby securing the
 block 514 to the support member 52. The block 514 and the key actuator 51
 are thus allowed to move along the slot 522 by loosening the bolt A. The
 horizontal section 523 defines a plurality of elongate slots 524 therein
 for each receiving a bolt A with a washer C.
 A slide plate 53 has a pair of connecting sections 531 respectively
 proximate front and rear edges thereof. Each connecting section 531
 defines a groove 532. The slots 524 of the horizontal section 523 of the
 support member 52 are aligned with the groove 532 of the front connecting
 section 531 and fixed on the slide plate 53 by means of the bolts A and
 washers C. The slide plate 53 is movable in the housing 10 thereby
 properly positioning the key testing device 50 with respect to a
 particular keyboard B to be tested. The support member 52 is selectively
 mounted to the front or rear groove 532 and this changes the position of
 the support member 52 and the key testing device 50 with respect to the
 keyboard B.
 A conveying device 60 comprises a rail 62 which is driven by motor 61 to
 reciprocally move in a direction substantially parallel to the keyboard B.
 The rail 62 is coupled to the connecting section 531 of the slide plate 53
 for moving the slide plate 53 along the rail 62.
 A signal adapter 70 is mounted on the rail 12. The adapter 70 has a number
 of sockets 71, 72, 73 for mating different keyboard cable end connector
 (not shown), such as ISA type connector or USB type connector, in order to
 transfer a key test signal caused by the actuation of a key B2 of the
 keyboard B to a control unit 80.
 The control unit 80 comprises a microprocessor based device, such as a
 programmable logic control (PLC) or a personal computer which receives the
 indicator test signal from the indicator testing device 40 and the key
 test signal from the signal adapter 70 that is connected to the keyboard
 B. Based on the signals, the control unit 80 determines if the indicators
 B1 and the keys B2 function properly. A fault warning signal is given off
 via a warning device 90 by the control unit 80 if either one of the
 indicators B1 and the keys B2 does not function properly. The control unit
 80 is electrically coupled to the key testing device 50 and the conveying
 device 60 for controlling the actuation of the key testing device 50 and
 the movement of the conveying device 60.
 The warning device 90 may be of any desired form. In the embodiment
 illustrated, the warning device 90 comprises a buzzer that is controlled
 and driven by the control unit 80 to give off the fault warning signal for
 indicating an abnormal condition of the keyboard B that is being tested.
 If desired, the warning device 90 may further comprise a light source
 which gives off a visual warning.
 Referring to FIG. 5 which shows a condition when a keyboard B is tested by
 the keyboard testing apparatus 100 of the present invention, as noted
 above, the keyboard B is clamped between the clamping members 20, 21 and
 the switch 42 is triggered, indicating the presence of the keyboard B. The
 retaining device 30 is actuated by the switch 42 to firmly retain the
 keyboard B in position. The indicators B1 of the keyboard B are turned on
 and the indicator testing device 40 detects the light emitted from the
 indicators B1. If an abnormal condition is determined, then the test stops
 and the control unit 80 gives off the fault warning signal via the warning
 device 90.
 A pair of indicators D1, D2 may be included which respectively indicate a
 normal condition and an abnormal condition of the keyboard B. The
 indicators D1, D2 are controlled by the control unit 80.
 After the indicator test is completed a key test is performed. FIG. 7 shows
 a key B2 actuated by the contact element 513 of a corresponding key
 actuator 51. The contact element 513 is moved by the conveying device 60
 to sequentially actuate the keys B2 of the keyboard for testing the keys
 B2 and a key test signal for each key B2 is generated and applied to the
 control unit 80. If an abnormal condition is determined by the control
 unit 80 during testing the keys B2, a fault warning signal is generated by
 means of the warning device 90 and the test stops. The abnormal key is
 recorded in the control unit 80 for further use in detailed inspection and
 repairing of the key.
 FIG. 8 shows a calibration process for the key actuators 51 of the key
 testing device 50. A contact pressure gauge 200 has a probe 210 which is
 sequentially and individually engaged by the contact element 513 of each
 key actuator 51 to obtain the contact force reading thereof The reading
 provides a reference for adjusting the pre-loaded spring 512 of each key
 actuator 51 to obtain a uniform pre-load on all key actuators 51.
 The pre-load of the key actuator 51 may be changed in accordance with the
 types of the keyboard to be tested in order to provide a more precise test
 result.
 The keyboard testing apparatus 100 provides a measure for automatically
 testing keyboards whereby testing keyboard may be performed efficiently
 and effectively to obtain accurate test result.
 Although the present invention has been described with reference to the
 preferred embodiments thereof, it is apparent to those skilled in the art
 that a variety of modifications and changes may be made without departing
 from the scope of the present invention which is intended to be defined by
 the appended claims.