CA1138235A - Fiber optic light pen - Google Patents
Fiber optic light penInfo
- Publication number
- CA1138235A CA1138235A CA000379801A CA379801A CA1138235A CA 1138235 A CA1138235 A CA 1138235A CA 000379801 A CA000379801 A CA 000379801A CA 379801 A CA379801 A CA 379801A CA 1138235 A CA1138235 A CA 1138235A
- Authority
- CA
- Canada
- Prior art keywords
- light
- fiber optic
- housing
- detector
- actuating means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
DOCKET T4185.01 FRA:1hw l FIBER OPTIC LIGHT PEN
2 ABSTRACT Of THE DISCLOSURE
3 A housing having a front portion and a rear 4 portion and an opening therein supports an actuator means projecting from the front portion. The actuator 6 means is slidably located within the opening of the 7 housing and has a light guiding aperture therein. At 8 least one fiber optic element having one end 9 associated with a detector has its other end located within the housing for receiving light projecting 11 through the light guiding aperture of the actuator 12 means. A switch means responsive to the movement of 13 the actuator means is located within the housing and 14 controls the detector to which the fiber optic element is connected. In use, the fiber optic light pen is 16 pressed against the screen of a CRT with which it is 17 associated causing the actuator means to move slidably 18 toward the rear portion of the housing, thereby 19 actuating the switch means which triggers the detector to detect light transmitted through the light guiding 21 aperture and the fiber optic element.
2 ABSTRACT Of THE DISCLOSURE
3 A housing having a front portion and a rear 4 portion and an opening therein supports an actuator means projecting from the front portion. The actuator 6 means is slidably located within the opening of the 7 housing and has a light guiding aperture therein. At 8 least one fiber optic element having one end 9 associated with a detector has its other end located within the housing for receiving light projecting 11 through the light guiding aperture of the actuator 12 means. A switch means responsive to the movement of 13 the actuator means is located within the housing and 14 controls the detector to which the fiber optic element is connected. In use, the fiber optic light pen is 16 pressed against the screen of a CRT with which it is 17 associated causing the actuator means to move slidably 18 toward the rear portion of the housing, thereby 19 actuating the switch means which triggers the detector to detect light transmitted through the light guiding 21 aperture and the fiber optic element.
Description
1~1.38~3~i 1 BACKGROUND Of THE INVENTION
2 1. Field of the Invention
3 The invention generally relates to a
4 light pen and, in particular, a fiber optic light pen employed in combination with an illuminated surface 6 such as a cathode ray tube, to sense information 7 displayed on the tube.
8 2. Description of the Prior Art 9 Optical light pens are well known in the prior art. Basically, there are two types of 11 light pens. The first type is disclosed in U.S.
12 Patent No. 4,182,956 and is used in reading coded 13 information appearing on the label of an item. Such 14 light pens typically have a light source which generates light intended to strike the region of the code. The second type of light pen is intended for 17 responding to visual information displayed on an 18 illuminated surface such as a cathode ray tube.
19 ~lthough the present invention is described with particular regard to this second type of light pen, it 21 should be understood that the inventive features of $
1~3~235i 1 the light pen disclosed herein may also be employed in 2 the first type of light pen.
3 Light pens of the prior art for use with a 4 color cathode ray tube (CRT) generally had problematical electrical noise. In particular, the 6 light detectors of prior art pens were located within 7 the light pen itself and would react to spurious 8 electrical pulses caused by the close proximity of the 9 detector to the CRT faceplate. These spurious pulses lû caused false detections to take place, especially when 11 the light pen was used to sense areas of low 12 brightness or luminance where the normal detector 13 output is low.
14 ûne way to avoid this noise problem W3S to provide a better electrical shielding for the light 16 pen's detector and amplifier circuitry. However, 17 increasing the shielding does not eliminate all the 18 noise, although the noise level will decrease.
It is an object of this invention to 21 provide a new and improved optical light pen emoloying 22 fiber optics.
23 It is a further object of this invention to 24 provide a fiber optic light pen assembly which is not susceptible to electrically induced noise when placed 26 close to a CRT.
1~.3~3~3~
1 The fiber optic light pen according to the 2 invention is for use in combination with a cathode ray 3 tube and a remote light detector to sense information 4 displayed on the tube. The pen includes a housing having a front portion and a rear portion with an 6 opening therethrough. An actuating means is slidably 7 located within the opening of the housing and projects 8 from the front portion of the housing. The actuating 9 means has a light guiding aperture associated with at least one fiber optic element which conducts the light 11 to the remotely located light detector where it is 12 detected. A switch in the light pen controls the 13 light detector circuitry and is responsive to the 14 position of the actuating means within the opening of the housing. In use, the front portion of the pen is 16 pressed against the cathode ray tube causing the 17 actuating means to slide rearwardly, triggering the 18 switch and activating the light detector. The light 19 detector detects light transmitted through the combination of the light guiding aperture of the 21 actuating means and the fiber optic element associated 22 therewith.
23 For a better understanding of the present 24 invention, together with other and further objects, reference is made to the following description7 taken ~31~
1 in conjunction with the accompanying drawings, and its 2 scope will be pointed out in the appended claims.
3 8RIEF DESCRIPTION ûF THE DRAWING
4 r igure 1 is a partial, longitudinal, cross-sectional view of a fiber optic light pen 6 according to the invention;
7 figure 2 is a side view of the actuator 8 employed in the light pen illustrated in Figure l;
9 Figure 3 is a front end view of the bracket 4 taken along lines 3-3 of Figure l; and ll Figure 4 is a partial, longitudinal, 12 cross-sectional view of an alternative embodiment of 13 the fiber optic light pen according to the invention.
As shown in Figure 1, the optical light pen 16 according to the invention has an outer housing member 17 3 comprising a cylindrical tube which may be 18 conveniently gripped by the user of the light pen.
19 Although the housing member 3 is illustrated as cylindrical, it is contemplated that the outer body of 21 the light pen may be any convenient shape for handling ~2 by a user. It is only necessary that the outer body 23 be provided with an opening, such as axial opening 3a, ~38~23S
1 for supporting the inner parts of the li~ht pen 2 according to the invention. The forward end 20 of the 3 light pen is provided with an opening 3b, through 4 which nose piece 1 projects, ~Nith inwardly tapering shoulders 3c for supporting the nose piece 1.
6 Generally, the nose piece 1 has a tapered portion la 7 integrally terminating in an engaging portion lb which 8 is axially and slidably mounted within the forward end 9 20 of axial opening 3a of the housing member 3. It is contemplated that the tapered end la of the nose piece 11 may contact the surface of the CRT with which the 12 light pen is employed.
13 The engaging portion lb of nose piece 1 14 abuts against an actuator 2 and is slidably arranged within the axial opening 3a of the housing member 3 16 and slidably arranged therein. The nose piece 1 and 17 actuator 2 form the actuating means of the invention.
18 The actuator 2 may best be appreciated by referring to 19 Figure 2. The actuator 2 is provided with a forward surface 2a, for contacting the engaging portion lb of 21~ the nose piece 1, and two rearward projecting prongs 22 15 and 16. Actuating prong 15 is provided with a bend 23 15a so that the tip 15b of the prong 15 is located 24 near the body member axis 21, indicated by a dotted line in figure 2. Parallel to the axis 21, guiding 26 prong 16 also projects rearwardly from the support 1~3E~'~3~
1 member 17. Prongs 15 and 16 engage switch bracket 4, 2 also located within the axial opening 3a of the 3 housing member 3. The rearward end 30 of the housing 4 member 3 is provided with internal threads 6 for engaging the external threads 7 on the switch bracket 6 4.
7 Figure 3 is a front end view of the switch 8 bracket 4 showing surface 4a. As can be appreciated 9 by referring to Figure 1, the switch bracket 4 is generally U-shaped, having an engaging portion 4b, a 11 threaded portion 4c and an interconnecting portion 12 4d. The engaging portion 4b is provided with two 13 openings 22 and 23 for receiving the prongs 15 and 16, 14 respectively. Portion 4b is also provided with opening 24 through which fiber optic bundle 9, 16 comprising at least one fiber optic element, passes.
17 Disposed on the interconnecting portion 4d 18 is switch 11, which is attached to portion 4d by 19 switch screw 13. The switch 11 is provided with a set of terminals lOa connected to switch wiring lOb which 21 for~s a part oF the wire harness 8. The opposing end, 22 or front end, of switch 11 is provided with a pressure 23 sensitive trip 12 in contact with rearward end 15b of 24 prong 15. Separating the switch bracket 4 from the actuator 2 is a coil spring 14 located axially 26 therebetween and within the axial opening ~a.
~13~3~35 1 Portion 4c of the switch bracket 4 is externally 2 threaded to engage the internal threads 6 of housing 3 member 3, thereby holding the switch bracket 4 rigidly 4 in place with respect to the housing member 3. The threaded portion 4c of the switch bracket 4 is also 6 provided with an axial opening 25 through which the 7 wire harness 8 passes. A set screw 26, perpendicular 8 to the harness 8, is provided within the portion 4c to 9 engage the wire harness 8 and hold it rigidly in place with respect to the switch bracket 4 and housing 11 member 3. The rearward end 30 of the housing member 3 12 is provided finally with an end cap 5 having external 13 threads 7a for engaging the internal threads 6 of the 14 housing member 3.
The wire harness 8 includes the fiber optic 16 bundle g and the switch wiring lOb. At the remote end 17 of wire harness 8 (not shown) bundle 9 terminates in a 18 fiber optic connector and switch wiring 106 terminates 19 in a wire connector. The fiber optic connector engages a light detector (not shown) for detecting 21 light transmitted by the fiber optic bundle. The wire 22 connector is connected to the light detector circuitry 23 so as to actuate the detector whenever switch 11 is 24 actuated by contact of tip 15b with pressure sensitive trip 12. The entire wire harness 8 projects through ~L~31323S
1 axial opening 5a in cap 5 and through the axial 2 opening 25 in the rear portion 4c of the switch 3 bracket 4. The harness 8 is held in place by set 4 screw 26. The wire harness 8 runs parallel to the interconnecting portion 4d of the switch bracket 4 and 6 the switch wiring lOb branches off from the harness 8 7 to connect to terminals l~a of the switch 11. The 8 fiber optic bundle 9 is routed around switch 11 and 9 within opening 24 in the forward portion 4b of the switch bracket 4, within the coil spring 14, between 11 the prongs 15 and 16 and through axial opening 2b in 12 support member 17.
13 The nose piece 1 includes light guiding 14 aperture 33 and supports an optional fiber optic lens 18, which is associated with the fiber optic bundle 9 16 by means of interface 19. It is contemplated that 17- interface 19 may be any convenient termination of the 18 bundle 9 which promotes the acceptance of light into lg the element or elements of the bundle 9. For example, the bundle 9 may terminate in a brass ferrule into 21 which the fiber optic element or elements are 22 adhesively secured. The end of the bundle 9 is then 23 polished to permit entry of light into the fiber optic 24 element or elements. The fiber optic bundle 9 and lens 18 are rigidly supported with respect to the 26 housing member 3 and switch bracket 4.
~.3~35 2 As described previously with respect to 3 Figures 1-4, the optical fiber bundle 9 and switch 4 wiring lOb feed and activate, respectively, a remotely located light detector (not shown). The light 6 detector is used to detect the light provided by the 7 CRT with which the light pen of the invention is being 8 employed. By feeding back a signal representing the 9 detected light from the detector to the CRT, the particular position of the light pen on the face of 11 the cathode ray tube can be determined and the image 12 or character information displayed at that position on 13 the CRT can be eliminated or changed.
14 A user grasps the light pen by housing member 3 and gently places the nose piece 1 against 16` the face of the CRT with which the pen is associated.
17 When the nose piece 1 is located at the desired 18 position on the face of the CRT, the housing member 3 19 is firmly pressed against the CRT face causing the 2û nose piece 1 to retract into axial opening 3a and move 21 axially with respect to the housing member 3. The 22 light pen is configured such that during the rearward 23 movement of the nose piece 1, the actuator 2 is also 24 moved rearwardly, due to the contact between the nose piece 1 and forward surface 2a of the actuator 2.
-lû -.
1~.3~
1 This rearward movement of the actuator 2 causes the 2 coil spring 14 to compress and also moves the prongs 3 15 and 16 rearwardly. Rearward movement of prong 15 4 engages the pressure sensitive trip 12 of the switch 11, thereby actuating the remotely located light 6 detector and detecting the light which is transmitted 7 to the detector by the fiber optic bundle 9.
8 The light pen body 3 is dimensioned in such 9 a way that the tip 18b of the fiber optic lens 18 or bundle 9, if no lens is used, is about a one-quarter 11 inch from the tip of the nose piece 1. In operation, 12 it is contemplated that the user would pick up the 13 light pen by housing member 3, place the tip 18b 14 against the face of the CRT and push gently toward the screen until an audible feedback signal indicates that 16 the light at that point has been detected. The 17 pressure against the tip of the actuator forces it to 18 axially move within opening 3a, closing switch 11.
19 which is normally open. The light from the CRT passes 2û through the light guiding aperture 33 in the nose 21 piece 1 to the fiber optic bundle 9 or optional lens 22 18 which focuses the light nn interface 19 and fiber 23 optic bundle 9. The light is transmitted along the ~3~
l fiber optic bundle 9, which is connected to the light 2 detector by a conventional fiber optic cable 3 connector. The connector is configured to position 4 the remote end of fiber optic bundle 9 adjacent to the light detector so that light transmitted by the bundle 9 strikes the detector with little or no loss. The 7 light detector device contemplated for use in 8 combination with a light pen according to the 9 invention is a conventional combination detector/amplifier. The output of this device is 11 applied to a conventional light pen amplifier and 12 pulse detector circuits associated with the CRT
13 chassis.
14 It should be noted that the use of the fiber optic bundle 9 permits great versatility in the 16 selection and use of light detectors. For example, to 17 change a particular detector for different response to 18 color, phosphor, time, etc., does not require a 19 complete change or redesign of the light pen assembly itself. Only the remotely located detector need be 21 changed. Furthermore, the light pen according to the 22 invention eliminates electrostatic interference with 23 sensitive light detector circuits. Static charges 24 which normally build on the CRT face plate and users' hands cause static discharge which significantly 26 affects conventional light pens employing light ~.38~3~
1 detectors within the head of the pen. The light pen 2 according to the invention is not affected by such 3 static charges and discharges because the light 4 detector circuitry may be remotely located.
In addition, the reliability of the light 6 pen of the invention is found to be significantly 7 improved over the prior art. The fact that the light 8 pen according to the invention has only one moving 9 part to actuate the switch 11 avoids the need for flexible wiring and moving light detectors, which are 11 normally employed in conventional light pens and are 12 subject to frequent failures.
13 It is also noted that the light pen 14 according to the invention improves producibility and maintainability by avoiding the need for miniature 16 circuitry located within the head of the light pen.
17 the design, according to the invention, allows 18 conventional circuit packaging of the light detector 19 in the chassis of the CRT, for example, and requires only the simple wiring of switch 11 in the light pen.
21 Figure 4 is an alternative embodiment of 22 the invention wherein the nose piece and actuator are 23 integrally combined into a single actuator assembly 24 100 located within the housing member 3. The assembly 100 is provided with support 101 for retaining the 26 optional fiber optic lens 18 and fiber optic bundle ~3~3~3S
1 9. The end of assembly 100 terminates in flange 102 2 for engaging switch 11 and trip 12 for actuating the 3 detector connected thereto. Switch 102 supports the 4 fiber optic bundle 9 and switch wiring lOb. Trip 12 is spring-biased in the normally open position and 6 abuts flange 102 which retains the assembly 100 in a 7 position projecting from the body 3. This alternative a embodiment operates in the same manner as the 9 embodiment of Figures 1-3.
8 2. Description of the Prior Art 9 Optical light pens are well known in the prior art. Basically, there are two types of 11 light pens. The first type is disclosed in U.S.
12 Patent No. 4,182,956 and is used in reading coded 13 information appearing on the label of an item. Such 14 light pens typically have a light source which generates light intended to strike the region of the code. The second type of light pen is intended for 17 responding to visual information displayed on an 18 illuminated surface such as a cathode ray tube.
19 ~lthough the present invention is described with particular regard to this second type of light pen, it 21 should be understood that the inventive features of $
1~3~235i 1 the light pen disclosed herein may also be employed in 2 the first type of light pen.
3 Light pens of the prior art for use with a 4 color cathode ray tube (CRT) generally had problematical electrical noise. In particular, the 6 light detectors of prior art pens were located within 7 the light pen itself and would react to spurious 8 electrical pulses caused by the close proximity of the 9 detector to the CRT faceplate. These spurious pulses lû caused false detections to take place, especially when 11 the light pen was used to sense areas of low 12 brightness or luminance where the normal detector 13 output is low.
14 ûne way to avoid this noise problem W3S to provide a better electrical shielding for the light 16 pen's detector and amplifier circuitry. However, 17 increasing the shielding does not eliminate all the 18 noise, although the noise level will decrease.
It is an object of this invention to 21 provide a new and improved optical light pen emoloying 22 fiber optics.
23 It is a further object of this invention to 24 provide a fiber optic light pen assembly which is not susceptible to electrically induced noise when placed 26 close to a CRT.
1~.3~3~3~
1 The fiber optic light pen according to the 2 invention is for use in combination with a cathode ray 3 tube and a remote light detector to sense information 4 displayed on the tube. The pen includes a housing having a front portion and a rear portion with an 6 opening therethrough. An actuating means is slidably 7 located within the opening of the housing and projects 8 from the front portion of the housing. The actuating 9 means has a light guiding aperture associated with at least one fiber optic element which conducts the light 11 to the remotely located light detector where it is 12 detected. A switch in the light pen controls the 13 light detector circuitry and is responsive to the 14 position of the actuating means within the opening of the housing. In use, the front portion of the pen is 16 pressed against the cathode ray tube causing the 17 actuating means to slide rearwardly, triggering the 18 switch and activating the light detector. The light 19 detector detects light transmitted through the combination of the light guiding aperture of the 21 actuating means and the fiber optic element associated 22 therewith.
23 For a better understanding of the present 24 invention, together with other and further objects, reference is made to the following description7 taken ~31~
1 in conjunction with the accompanying drawings, and its 2 scope will be pointed out in the appended claims.
3 8RIEF DESCRIPTION ûF THE DRAWING
4 r igure 1 is a partial, longitudinal, cross-sectional view of a fiber optic light pen 6 according to the invention;
7 figure 2 is a side view of the actuator 8 employed in the light pen illustrated in Figure l;
9 Figure 3 is a front end view of the bracket 4 taken along lines 3-3 of Figure l; and ll Figure 4 is a partial, longitudinal, 12 cross-sectional view of an alternative embodiment of 13 the fiber optic light pen according to the invention.
As shown in Figure 1, the optical light pen 16 according to the invention has an outer housing member 17 3 comprising a cylindrical tube which may be 18 conveniently gripped by the user of the light pen.
19 Although the housing member 3 is illustrated as cylindrical, it is contemplated that the outer body of 21 the light pen may be any convenient shape for handling ~2 by a user. It is only necessary that the outer body 23 be provided with an opening, such as axial opening 3a, ~38~23S
1 for supporting the inner parts of the li~ht pen 2 according to the invention. The forward end 20 of the 3 light pen is provided with an opening 3b, through 4 which nose piece 1 projects, ~Nith inwardly tapering shoulders 3c for supporting the nose piece 1.
6 Generally, the nose piece 1 has a tapered portion la 7 integrally terminating in an engaging portion lb which 8 is axially and slidably mounted within the forward end 9 20 of axial opening 3a of the housing member 3. It is contemplated that the tapered end la of the nose piece 11 may contact the surface of the CRT with which the 12 light pen is employed.
13 The engaging portion lb of nose piece 1 14 abuts against an actuator 2 and is slidably arranged within the axial opening 3a of the housing member 3 16 and slidably arranged therein. The nose piece 1 and 17 actuator 2 form the actuating means of the invention.
18 The actuator 2 may best be appreciated by referring to 19 Figure 2. The actuator 2 is provided with a forward surface 2a, for contacting the engaging portion lb of 21~ the nose piece 1, and two rearward projecting prongs 22 15 and 16. Actuating prong 15 is provided with a bend 23 15a so that the tip 15b of the prong 15 is located 24 near the body member axis 21, indicated by a dotted line in figure 2. Parallel to the axis 21, guiding 26 prong 16 also projects rearwardly from the support 1~3E~'~3~
1 member 17. Prongs 15 and 16 engage switch bracket 4, 2 also located within the axial opening 3a of the 3 housing member 3. The rearward end 30 of the housing 4 member 3 is provided with internal threads 6 for engaging the external threads 7 on the switch bracket 6 4.
7 Figure 3 is a front end view of the switch 8 bracket 4 showing surface 4a. As can be appreciated 9 by referring to Figure 1, the switch bracket 4 is generally U-shaped, having an engaging portion 4b, a 11 threaded portion 4c and an interconnecting portion 12 4d. The engaging portion 4b is provided with two 13 openings 22 and 23 for receiving the prongs 15 and 16, 14 respectively. Portion 4b is also provided with opening 24 through which fiber optic bundle 9, 16 comprising at least one fiber optic element, passes.
17 Disposed on the interconnecting portion 4d 18 is switch 11, which is attached to portion 4d by 19 switch screw 13. The switch 11 is provided with a set of terminals lOa connected to switch wiring lOb which 21 for~s a part oF the wire harness 8. The opposing end, 22 or front end, of switch 11 is provided with a pressure 23 sensitive trip 12 in contact with rearward end 15b of 24 prong 15. Separating the switch bracket 4 from the actuator 2 is a coil spring 14 located axially 26 therebetween and within the axial opening ~a.
~13~3~35 1 Portion 4c of the switch bracket 4 is externally 2 threaded to engage the internal threads 6 of housing 3 member 3, thereby holding the switch bracket 4 rigidly 4 in place with respect to the housing member 3. The threaded portion 4c of the switch bracket 4 is also 6 provided with an axial opening 25 through which the 7 wire harness 8 passes. A set screw 26, perpendicular 8 to the harness 8, is provided within the portion 4c to 9 engage the wire harness 8 and hold it rigidly in place with respect to the switch bracket 4 and housing 11 member 3. The rearward end 30 of the housing member 3 12 is provided finally with an end cap 5 having external 13 threads 7a for engaging the internal threads 6 of the 14 housing member 3.
The wire harness 8 includes the fiber optic 16 bundle g and the switch wiring lOb. At the remote end 17 of wire harness 8 (not shown) bundle 9 terminates in a 18 fiber optic connector and switch wiring 106 terminates 19 in a wire connector. The fiber optic connector engages a light detector (not shown) for detecting 21 light transmitted by the fiber optic bundle. The wire 22 connector is connected to the light detector circuitry 23 so as to actuate the detector whenever switch 11 is 24 actuated by contact of tip 15b with pressure sensitive trip 12. The entire wire harness 8 projects through ~L~31323S
1 axial opening 5a in cap 5 and through the axial 2 opening 25 in the rear portion 4c of the switch 3 bracket 4. The harness 8 is held in place by set 4 screw 26. The wire harness 8 runs parallel to the interconnecting portion 4d of the switch bracket 4 and 6 the switch wiring lOb branches off from the harness 8 7 to connect to terminals l~a of the switch 11. The 8 fiber optic bundle 9 is routed around switch 11 and 9 within opening 24 in the forward portion 4b of the switch bracket 4, within the coil spring 14, between 11 the prongs 15 and 16 and through axial opening 2b in 12 support member 17.
13 The nose piece 1 includes light guiding 14 aperture 33 and supports an optional fiber optic lens 18, which is associated with the fiber optic bundle 9 16 by means of interface 19. It is contemplated that 17- interface 19 may be any convenient termination of the 18 bundle 9 which promotes the acceptance of light into lg the element or elements of the bundle 9. For example, the bundle 9 may terminate in a brass ferrule into 21 which the fiber optic element or elements are 22 adhesively secured. The end of the bundle 9 is then 23 polished to permit entry of light into the fiber optic 24 element or elements. The fiber optic bundle 9 and lens 18 are rigidly supported with respect to the 26 housing member 3 and switch bracket 4.
~.3~35 2 As described previously with respect to 3 Figures 1-4, the optical fiber bundle 9 and switch 4 wiring lOb feed and activate, respectively, a remotely located light detector (not shown). The light 6 detector is used to detect the light provided by the 7 CRT with which the light pen of the invention is being 8 employed. By feeding back a signal representing the 9 detected light from the detector to the CRT, the particular position of the light pen on the face of 11 the cathode ray tube can be determined and the image 12 or character information displayed at that position on 13 the CRT can be eliminated or changed.
14 A user grasps the light pen by housing member 3 and gently places the nose piece 1 against 16` the face of the CRT with which the pen is associated.
17 When the nose piece 1 is located at the desired 18 position on the face of the CRT, the housing member 3 19 is firmly pressed against the CRT face causing the 2û nose piece 1 to retract into axial opening 3a and move 21 axially with respect to the housing member 3. The 22 light pen is configured such that during the rearward 23 movement of the nose piece 1, the actuator 2 is also 24 moved rearwardly, due to the contact between the nose piece 1 and forward surface 2a of the actuator 2.
-lû -.
1~.3~
1 This rearward movement of the actuator 2 causes the 2 coil spring 14 to compress and also moves the prongs 3 15 and 16 rearwardly. Rearward movement of prong 15 4 engages the pressure sensitive trip 12 of the switch 11, thereby actuating the remotely located light 6 detector and detecting the light which is transmitted 7 to the detector by the fiber optic bundle 9.
8 The light pen body 3 is dimensioned in such 9 a way that the tip 18b of the fiber optic lens 18 or bundle 9, if no lens is used, is about a one-quarter 11 inch from the tip of the nose piece 1. In operation, 12 it is contemplated that the user would pick up the 13 light pen by housing member 3, place the tip 18b 14 against the face of the CRT and push gently toward the screen until an audible feedback signal indicates that 16 the light at that point has been detected. The 17 pressure against the tip of the actuator forces it to 18 axially move within opening 3a, closing switch 11.
19 which is normally open. The light from the CRT passes 2û through the light guiding aperture 33 in the nose 21 piece 1 to the fiber optic bundle 9 or optional lens 22 18 which focuses the light nn interface 19 and fiber 23 optic bundle 9. The light is transmitted along the ~3~
l fiber optic bundle 9, which is connected to the light 2 detector by a conventional fiber optic cable 3 connector. The connector is configured to position 4 the remote end of fiber optic bundle 9 adjacent to the light detector so that light transmitted by the bundle 9 strikes the detector with little or no loss. The 7 light detector device contemplated for use in 8 combination with a light pen according to the 9 invention is a conventional combination detector/amplifier. The output of this device is 11 applied to a conventional light pen amplifier and 12 pulse detector circuits associated with the CRT
13 chassis.
14 It should be noted that the use of the fiber optic bundle 9 permits great versatility in the 16 selection and use of light detectors. For example, to 17 change a particular detector for different response to 18 color, phosphor, time, etc., does not require a 19 complete change or redesign of the light pen assembly itself. Only the remotely located detector need be 21 changed. Furthermore, the light pen according to the 22 invention eliminates electrostatic interference with 23 sensitive light detector circuits. Static charges 24 which normally build on the CRT face plate and users' hands cause static discharge which significantly 26 affects conventional light pens employing light ~.38~3~
1 detectors within the head of the pen. The light pen 2 according to the invention is not affected by such 3 static charges and discharges because the light 4 detector circuitry may be remotely located.
In addition, the reliability of the light 6 pen of the invention is found to be significantly 7 improved over the prior art. The fact that the light 8 pen according to the invention has only one moving 9 part to actuate the switch 11 avoids the need for flexible wiring and moving light detectors, which are 11 normally employed in conventional light pens and are 12 subject to frequent failures.
13 It is also noted that the light pen 14 according to the invention improves producibility and maintainability by avoiding the need for miniature 16 circuitry located within the head of the light pen.
17 the design, according to the invention, allows 18 conventional circuit packaging of the light detector 19 in the chassis of the CRT, for example, and requires only the simple wiring of switch 11 in the light pen.
21 Figure 4 is an alternative embodiment of 22 the invention wherein the nose piece and actuator are 23 integrally combined into a single actuator assembly 24 100 located within the housing member 3. The assembly 100 is provided with support 101 for retaining the 26 optional fiber optic lens 18 and fiber optic bundle ~3~3~3S
1 9. The end of assembly 100 terminates in flange 102 2 for engaging switch 11 and trip 12 for actuating the 3 detector connected thereto. Switch 102 supports the 4 fiber optic bundle 9 and switch wiring lOb. Trip 12 is spring-biased in the normally open position and 6 abuts flange 102 which retains the assembly 100 in a 7 position projecting from the body 3. This alternative a embodiment operates in the same manner as the 9 embodiment of Figures 1-3.
Claims (4)
- Claim 1. A light pen for use in combination with an illuminated display surface and a remotely located light detector to sense information displayed on the surface, said apparatus comprising:
(a) housing having a front portion and a rear portion with an opening therein;
(b) actuating means slidably located within the opening of said housing and projecting from the front portion of said housing, said actuating means having a light guiding aperture therethrough;
(c) at least one fiber optic element having one end associated with said light detector and having the other end associated with the light guiding aperture of said actuating means; and (d) switch means for controlling said light detector in response to the position of the actuating means within the opening of said housing, whereby pressing the front portion of said housing and said projecting actuating means against said display surface causes said actuating means to slide within the opening thereby actuating said switch means and said light detector to detect light transmitted through the light guiding aperture and said fiber optic element associated therewith. - Claim 2. The light pen of claim 1 wherein said actuating means comprises a slidable member located within the opening and abutting against a nose piece projecting from the front portion of the housing.
- Claim 3. The light pen of claim 2 wherein said fiber optic element terminates within said slidable member and said nose piece supports a fiber optic lens for focusing light passing through the light guiding aperture onto the fiber optic element.
- Claim 4. The light pen of claim 3 wherein said switch means comprises a pressure actuated trip switch responsive to the movement of said actuating means.
EXCLUSIVE PROPERTY OF PRIVILEGE IS CLAIMED ARE
DEFINED AS FOLLOWS:
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US20062980A | 1980-10-27 | 1980-10-27 | |
| US06/200,629 | 1980-10-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1138235A true CA1138235A (en) | 1982-12-28 |
Family
ID=22742514
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379801A Expired CA1138235A (en) | 1980-10-27 | 1981-06-15 | Fiber optic light pen |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS57103536A (en) |
| CA (1) | CA1138235A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4490607A (en) * | 1982-07-22 | 1984-12-25 | Igt | Pinhole objective fibre optic light pen |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3777153A (en) * | 1972-05-17 | 1973-12-04 | Sperry Rand Corp | Fiber optics light pen |
-
1981
- 1981-06-15 CA CA000379801A patent/CA1138235A/en not_active Expired
- 1981-10-27 JP JP56172685A patent/JPS57103536A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4490607A (en) * | 1982-07-22 | 1984-12-25 | Igt | Pinhole objective fibre optic light pen |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57103536A (en) | 1982-06-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |