CA1140068A - Method and apparatus for sensing the position of a character printing element - Google Patents
Method and apparatus for sensing the position of a character printing elementInfo
- Publication number
- CA1140068A CA1140068A CA000310367A CA310367A CA1140068A CA 1140068 A CA1140068 A CA 1140068A CA 000310367 A CA000310367 A CA 000310367A CA 310367 A CA310367 A CA 310367A CA 1140068 A CA1140068 A CA 1140068A
- Authority
- CA
- Canada
- Prior art keywords
- light
- character
- beams
- spaces
- character wheel
- 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.)
- Expired
Links
- 238000007639 printing Methods 0.000 title claims abstract description 39
- 238000000034 method Methods 0.000 title claims description 7
- 238000004804 winding Methods 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 claims description 6
- 229910052729 chemical element Inorganic materials 0.000 claims description 5
- 229920000136 polysorbate Polymers 0.000 claims description 4
- 241000723353 Chrysanthemum Species 0.000 description 7
- 235000005633 Chrysanthemum balsamita Nutrition 0.000 description 7
- 241000237858 Gastropoda Species 0.000 description 4
- 238000010586 diagram Methods 0.000 description 1
- 230000009975 flexible effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J1/00—Typewriters or selective printing mechanisms characterised by the mounting, arrangement or disposition of the types or dies
- B41J1/22—Typewriters or selective printing mechanisms characterised by the mounting, arrangement or disposition of the types or dies with types or dies mounted on carriers rotatable for selection
- B41J1/24—Typewriters or selective printing mechanisms characterised by the mounting, arrangement or disposition of the types or dies with types or dies mounted on carriers rotatable for selection the plane of the type or die face being perpendicular to the axis of rotation
- B41J1/28—Carriers stationary for impression, e.g. with the types or dies not moving relative to the carriers
- B41J1/30—Carriers stationary for impression, e.g. with the types or dies not moving relative to the carriers with the types or dies moving relative to the carriers or mounted on flexible carriers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J7/00—Type-selecting or type-actuating mechanisms
- B41J7/96—Means checking correctness of setting
Landscapes
- Character Spaces And Line Spaces In Printers (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A printing element comprises a daisy-like array wherein the character elements are supported at the ends of a plurality of radially extending beams so as to form a substantially circular array. The rotary position of the array is directly and optically sensed by a plurality of light sources which direct lighttoward the beams and through the spaces therebetween to a plurality of light detectors. Various characters of the printing element which forms the rotor of a stepper motor are stopped at the print postition in response to feedback provided by the light detector.
A printing element comprises a daisy-like array wherein the character elements are supported at the ends of a plurality of radially extending beams so as to form a substantially circular array. The rotary position of the array is directly and optically sensed by a plurality of light sources which direct lighttoward the beams and through the spaces therebetween to a plurality of light detectors. Various characters of the printing element which forms the rotor of a stepper motor are stopped at the print postition in response to feedback provided by the light detector.
Description
1~0C~6~
Backqround of the Invention This invention relates to printing elements, and more particularly, to printing elements of the type utilized in serial impact printers.
The printing elements of serial impact printers comprise a plurality of characters which are sequentially moved to the printing position on a copy medium. The print-ing element is forced and deflected into contact with a marking or inking medium which in turn contacts the copy medium by appropriate means such as a solenoid-actuated hammer .
One particularly popular printing element com-prises a daisy-like array of character elements which are supported at the end of a plurality of radially extending beams.
Such a daisy-like printing element is disclosed in copending ~anadian application Serial No. 303,683, filed May 18, 1978. The particular printing element as disclosed therein additionally includes inteyral rotor elements which are lo-cated in the hub which forms the movable magnetic structureor rotor of a rotary stepper motor.
When serial irnpact printers are capable of operat-~ ing in an automatic~ high speed mode t it becomes particu-larly important to continually monitor the position o~ the character element and provide appropriate feedback to assure that the print wheel comes to rest a-' exactly the right po-~ ion after approachina that position at hi~h speed. ~ere-tofore, this feedback has been accomplished by means coupled to the drive shaft associated with the daisy printing ele-ment but not the daisy printing element itself. Accordingly,the possibility of feedback error with respect to the exact position of the daisy printing element exists if there is
Backqround of the Invention This invention relates to printing elements, and more particularly, to printing elements of the type utilized in serial impact printers.
The printing elements of serial impact printers comprise a plurality of characters which are sequentially moved to the printing position on a copy medium. The print-ing element is forced and deflected into contact with a marking or inking medium which in turn contacts the copy medium by appropriate means such as a solenoid-actuated hammer .
One particularly popular printing element com-prises a daisy-like array of character elements which are supported at the end of a plurality of radially extending beams.
Such a daisy-like printing element is disclosed in copending ~anadian application Serial No. 303,683, filed May 18, 1978. The particular printing element as disclosed therein additionally includes inteyral rotor elements which are lo-cated in the hub which forms the movable magnetic structureor rotor of a rotary stepper motor.
When serial irnpact printers are capable of operat-~ ing in an automatic~ high speed mode t it becomes particu-larly important to continually monitor the position o~ the character element and provide appropriate feedback to assure that the print wheel comes to rest a-' exactly the right po-~ ion after approachina that position at hi~h speed. ~ere-tofore, this feedback has been accomplished by means coupled to the drive shaft associated with the daisy printing ele-ment but not the daisy printing element itself. Accordingly,the possibility of feedback error with respect to the exact position of the daisy printing element exists if there is
- 2 -`` 1~4~8 any misalignment between the daisy printing element and the source of feedback despite the complexity of the system.
Moreover, the use of the printing element disclosed in the aforesaid application Serial No. 303,683 eliminates the drive shaft and the possibility of utilizing feedback coupled to that drive shaft.
U. S. patent 3~651,916 - Becchi discloses a daisy printing element in combination with an optical sensor which optically communicates with the beams or petals of the daisy-like array by means of a light source and a detector located on opposite sides thereof. The daisy printing ele-ment is continuously rotated (i.e., does not come to rest) and the signal generated by the sensor controls the carriage and hammer of the printer and not the position of the print-ing element. The drive of the printing element is not therefore controlled in response to the direct sensing of the beams or petals.
Summary of the Invention It is an object of the invention to provide a novel print wheel for a printer.
It is a more specific object of this invention to provide improved accuracy in sensing the position of a character element in a printer.
It is an even more specific object of this invention to provide improved accuracy in the feedback signal controlling the position of the printing element of the daisy-type.
It is also an object of this invention to simplify the manner in which the position of the daisy printing ele-ment is sensed.
In accordance with a further aspect of the in-vention, a printing system for positioning character ele-ments including a rotary stepper motor stator comprises:
, .
!? 3 a plurality of windings associated with various phases of said motor, a character wheel having a hub carrying a plur-ality of magnetic rotor elements, a plu~ality of beams extend-ing radially outwardly from the hub and character elements supported by the radial outer extremity of the beams in a substantially circular array in fixed relationship with res-pect to said rotor elements, feedback means for sensing the position of said character wheel, means for rotatably driving and stopping said character wheel in response to the sensed position so as to stop a particular character element at-a predetermined position, said character wheel having a sub-stantially uniform pattern of beams and spaces around the entire circumference of said character wheel radially outwardly from said hub, said feedback means comprising means for direct-ly sensing said pattern, and means for driving the windings associated with said various phases of said stepper motor in response to said sensing.
From a still further aspect, and in accordance with the invention, there is provided a method of operating a printing system comprising a rotary stepper motor including a stator having a plurality of windings associated therewith, a character wheel including a hub carrying a plur-ality of rotor elements and a substantially uniform pattern of beams and spaces around the entire circumference of the wheel radially outwardly from said hub, said pattern including, character elements supported at the radial outer extremities of said beams and nammer means adapted to strike said char-acter elements, said method comprises: directing light at said beams and spaces as said character wheel rotates, directly sensing the variation in light as said beams pass therethrough for determining the position of said character wheel, driving the windings associated with said phases of said stator in response to the sensed light variations; stopping the charact-er wheel in response to the determined position of said char-acter wheel as sensed by the variation in light, and actuating the hammer means to strïke a character element.
In a preferred embodiment, the sensing means com-prises optical sensor means including light emitting means located on one side of the printing element for directing light between and at the beams and light detecting means located on the opposite side of the printing element ~or detecting the light. The light emitting means may comprise a first plurality of light sources having substantially equal spaces and a first plurality of light detectors juxta-posed to said first plurality of light sources and having substantially equal spaces therebetween. In addition, an equally spaced second pluraiity of llght sources and an equall.y spaced second plurality of ligh-t detectors may be utilized where the space between the first plurality and the second plurality differs from the spaces between the light emitting sources and the light detectors within said first plurality and said second plurality.
- 4a -.;
~1~0~6~
The preferred embodiment may also include means for adjusting the light emi-tting means and the light detect~
ing means on an arcuate path substantially concentric with the character element.
In the embodiment wherein the means for rotatably driving the printing element comprises the rotary stepper motor, the printing element comprises the rotor thereof including a plurality of arcuately arranged rotor elements located on the hub. Additional drive means move the rotary stepper motor and the character - 4b -~"'`
L40~)68 1 element relative ~o the copy medium. Hammer means strike 2 the character elements of the printing element to force the
Moreover, the use of the printing element disclosed in the aforesaid application Serial No. 303,683 eliminates the drive shaft and the possibility of utilizing feedback coupled to that drive shaft.
U. S. patent 3~651,916 - Becchi discloses a daisy printing element in combination with an optical sensor which optically communicates with the beams or petals of the daisy-like array by means of a light source and a detector located on opposite sides thereof. The daisy printing ele-ment is continuously rotated (i.e., does not come to rest) and the signal generated by the sensor controls the carriage and hammer of the printer and not the position of the print-ing element. The drive of the printing element is not therefore controlled in response to the direct sensing of the beams or petals.
Summary of the Invention It is an object of the invention to provide a novel print wheel for a printer.
It is a more specific object of this invention to provide improved accuracy in sensing the position of a character element in a printer.
It is an even more specific object of this invention to provide improved accuracy in the feedback signal controlling the position of the printing element of the daisy-type.
It is also an object of this invention to simplify the manner in which the position of the daisy printing ele-ment is sensed.
In accordance with a further aspect of the in-vention, a printing system for positioning character ele-ments including a rotary stepper motor stator comprises:
, .
!? 3 a plurality of windings associated with various phases of said motor, a character wheel having a hub carrying a plur-ality of magnetic rotor elements, a plu~ality of beams extend-ing radially outwardly from the hub and character elements supported by the radial outer extremity of the beams in a substantially circular array in fixed relationship with res-pect to said rotor elements, feedback means for sensing the position of said character wheel, means for rotatably driving and stopping said character wheel in response to the sensed position so as to stop a particular character element at-a predetermined position, said character wheel having a sub-stantially uniform pattern of beams and spaces around the entire circumference of said character wheel radially outwardly from said hub, said feedback means comprising means for direct-ly sensing said pattern, and means for driving the windings associated with said various phases of said stepper motor in response to said sensing.
From a still further aspect, and in accordance with the invention, there is provided a method of operating a printing system comprising a rotary stepper motor including a stator having a plurality of windings associated therewith, a character wheel including a hub carrying a plur-ality of rotor elements and a substantially uniform pattern of beams and spaces around the entire circumference of the wheel radially outwardly from said hub, said pattern including, character elements supported at the radial outer extremities of said beams and nammer means adapted to strike said char-acter elements, said method comprises: directing light at said beams and spaces as said character wheel rotates, directly sensing the variation in light as said beams pass therethrough for determining the position of said character wheel, driving the windings associated with said phases of said stator in response to the sensed light variations; stopping the charact-er wheel in response to the determined position of said char-acter wheel as sensed by the variation in light, and actuating the hammer means to strïke a character element.
In a preferred embodiment, the sensing means com-prises optical sensor means including light emitting means located on one side of the printing element for directing light between and at the beams and light detecting means located on the opposite side of the printing element ~or detecting the light. The light emitting means may comprise a first plurality of light sources having substantially equal spaces and a first plurality of light detectors juxta-posed to said first plurality of light sources and having substantially equal spaces therebetween. In addition, an equally spaced second pluraiity of llght sources and an equall.y spaced second plurality of ligh-t detectors may be utilized where the space between the first plurality and the second plurality differs from the spaces between the light emitting sources and the light detectors within said first plurality and said second plurality.
- 4a -.;
~1~0~6~
The preferred embodiment may also include means for adjusting the light emi-tting means and the light detect~
ing means on an arcuate path substantially concentric with the character element.
In the embodiment wherein the means for rotatably driving the printing element comprises the rotary stepper motor, the printing element comprises the rotor thereof including a plurality of arcuately arranged rotor elements located on the hub. Additional drive means move the rotary stepper motor and the character - 4b -~"'`
L40~)68 1 element relative ~o the copy medium. Hammer means strike 2 the character elements of the printing element to force the
3 character elemPnts against the copy medium~
4 Brief Descri~tion of the Drawin~s Figo 1 is a top view of a printing apparatus rep-6 resenting a pre~erred embodimen~ of the lnvention;
7 Fig~ 2 is an e~ploded view o~ the printing ele 8 ment sensing mechanismg 9 Fig. 3 is an elevational view of the system shown in Fig~ 1 ~rom the side o the platen;
11 Fig. 4 is an enlarged ~ragmentary sectional view 12 o the sensor sh~wn in Fig, 2~
13 Fig. 5 is an enlarged fragmentary sectional view 14 showing the printing element and a por~ion of the sensor lS shown in Fig. 2;
16 Figo 6 ~ a partial ~eetional vlew sh~w~ng ~he 17 adjustable mounting for the ~ensor o~ Fig~ 2;
18 Figo 7 is a sectional view taken al~ng line 7~7 of 19 Fig~ 6; and Fig. 8 is a blQck diagr~m of ~ eedback loop for 21 controIling the printing element.
22 Detailed Descript _n of a Pr_ferred Embodiment 23 A portion of a printer or typewri~er as shown in 24 Fig. 1 includes a print wheel 10 mounted on a carriage 12 which is adapted to move in a direction parallel with the 26 axis of a platen (not ~h~wn) so as ~o posi~ion the print 27 wheel 10 at various po$itions along a prînt receiving medi-28 um. As the carriage 12 is moved, the print wheel lO is ro~
29 tated by a rotary stepper motor 14 mounted on the carriage 12.
31 The motor 14 comprises a rotor integrally ~vrmed 32 with the printing element or wheel 10 and a stator comprising ~ 5 --6~
a first excited portion 16 and a second unexcited portion 18.
The excited portion 16 includes windings 20 associated with various poles or phases of the stepper motor 14. Additional details of the rotary stepper motor and the wheel 10 are disclosed in copending application Serial ~o. 303,683, assigned to the assignee of this invention.
As also shown in Fig. 1, the carriage 12 for the print wheel 10 is coupled to and driven by a passive slider (not shown) of a high performance linear stepper motor in-cluding a stator having an active portion 22 and a passive portion 24 so as to define a stator-to-stator air gap 26.
The active portion 22 of the stator is energized by windings 28 located at each of the pole positions 30 which extend along the length of the stator 26. Further details concern-ing the high performance linear stepper motor may be found in Canadian Patent No. 1,115,808, assigned to the assignee -~ of this invention.
The carriage 12 is supported on the stator of the linear stepper motor by means of roller bearings 32 and other bearings disclosed in the aforesaid patent no. 1,115,808.
Bracket 34 associated with one such bearing is disclosed in Fig. 1.
Referring to Fig. 3, the printing element or print wheel 10 referred to with respect to Fig. 1 comprises a hub 36 which supports a plurality of radially extending, flexi-ble beams 38 which are terminated at the radial outer ex-tremities thereof by character elements which are mounted on character slugs 40. Rotor elements 42 are inserted in the hub 3~ so as to be integrally formed with the print wheel 30 10. The character slugs 40 are impacted by a hammer (not ~ ~ 1 40 ~
1 shown~ SQ as ~o flex or deform ~he beams and drive ~he 2 character elements in~o ~ontact with an ink ribbon which in 3 turn eontacts the copy medium supported by the platen.
4 In accordance with this inventiona the position of the print wheel 10 is sensed and determined by dircctly and 6 op~ically sensing the beams 38 and the spaces therebetween, 7 More particularly, optical sensor means 44 ls provided a3 8 shown in Fig. 1 and Fig. 4 or sensing the variation in 9 light as the relatively opaque beams 38 and the intermadiate transpsrent spaces or openings rotateO
11 As bes~ shown in Figo 4, the sensor means 44 com-12 prises a bracket 46 through which the beams 38 and the 13 character slugs 40 of the print wheel 10 pass as the print 14 wheel 10 rotates. One side 48 of the bracket 46 carries a light emit~ing means 50 and the other side o~ the bracket 16 46 carries light detector means 54 As best shown in Figs~
17 2 and 5, the light emitting means may, in order to increase 18 reliability, comprise a first plurality of light sources 56 19 such as light emitting diodes and a first plurality o~ light detecting means such as a photo diode one of which is only 21 partially shown. The equal spaces between the first plu-22 rality of light sources and the fir3t plurality of light 23 detectors substantially corresponds with ~he equal spaces 24 between pairs of beams 38, i.e~, space between every other pair of beams 38. As also shown in Figso 2 and 5, the 2~ light emitting means further comprises a second plurality of 27 llght sources 58 and a second plurali~y of light detectors 28 no~ shown. The space between the first plurality 56 and ~he 29 second plurality 58 differs from the spacing between the light sources and detectors within ~he first plurality 56 31 and the second plurality 58 so as to generate signals pro~
32 viding information as to the direction or rotation of the print wheel 10. The sensor 44 includes an additional light source 61 and a detector 62 for sensing coded openings 59 carried by the print wheel 10 as described in Canadian Patent ~o. 1,096,802, which is assigned to the assignee of this invention.
By sensing the position of the print wheel 10 directly from the beams 38 and the openings therebetween, the position of the character elements mounted on the slugs 40 may be assured. Moreover, the mechanism for sensing the position of the character elements is greatly simplified.
In accordance with another important aspect of the invention, the sensor 44 is mounted for adjustment such that the light emitting means 50 (i.e., the pluralities 56 and 58 of light sources) and the light detecting means (i.e~, the first and second plurality of light detectors) may be moved along an arcuate path substantially concentric with the character element. In this connection, the bracket ~4 as shown in Figs. 2 and 4-6 is attached to a supp~rt 60 which is in turn slidably mounted on a member 62 including a track 64. The member 60 as shown in Fig. 6 includes a slot 66 formed by portions 68 and 70 which is adapted to receive the track 64 and a spring member 72 as shown in Figs. 2 and 6.
The spring 72 forces the track outwardly against the wall of the portion 70 which is arcuately formed so as to conform with the track 64 and define the arcuate path of adjustment.
Adjustment is accomplished by means of a screw 74 as best shown in Figs. 2 and 7 which threadedly engages a sleeve 76 which is carried by and secured to the support member 60. By fixing the head position of the screw 74 by means of a pin 7~3 as best shown in Figs. 2 and 7, the sleeve or nut 76 is forced to rise or descend as the screw 74 is ,~, ~ ,.
140~68 turned thereby raising or lowering the support member 60 along the defined arcuate path as well as the bracket 44.
An additional screw 80 and an associated nut 82 are utilized to lock the bracket 44 in place. In this connection, a slot 84 as best shown in Figs. 2 and 6 is provided in the support member 60. With the screw 80 and the nut 82 loose, the sup-port member 60 may slide relative to the screw 80 and the nut 82 thereby permitting adjustment of the bracket 44.
Fig. 8 discloses a block diagram of a feedback sensor system utilizing the output of the sensor 44. As shown, a position determining circuit 90 utilizes the output from the sensor 44 to generate a signal representing the position of the print wheel. The output from the position-ing determining circuit 90 is then applied to motor drive circuitry 92. The motor drive is utilized to energize the winding 20 as shown in Fig. 1 of the stator 94 which is mag-netically coupled to the rotor 96 integrally formed with the print wheel 10 so as to control the stopping position of the print wheel 10. Of course, the beams of the print wheel which are integrally formed with the rotor 96 are directly and optically coupled to the sensor 44 as described in the foregoing. Details concerning the position determining cir-cuit 90 and the motor drive circuit 92 may be found in co-pending Canadian application serial no. 310,368, filed August 30, 1978, assigned to the assignee of this invention.
In accordance with another impDrtant aspect of this invention, the frequently used handle or flag 100 shown in Fig. 3 which extends radially outwardly from the hub 36 includes a plurality of openings 102 having spaces therebe-tween which are substantially identical to the circumferen-tial width of the beams 38. This allows the feedback . -- g _ ~4~ 6~3 !
1 control of thQ printing elemen~ 10 even when the handle 100 2 is in the vicinity of the sensor 44~ In other words, the 3 motor is capable of stopping at a plurality of positions 4 with the handle generally in the printing position. Of oourse, the handle can be eliminated w~th beams 38 substi-6 tuted in order to fill thP area of the handle lOQ ~o as no~
7 to interfere wit~ the feedback.
8 Although de~ails of a particular preferred embodi-9 ment of the invention have been shown and de~cribed, it will be unders~ood that various modifications may be made wi~h-11 out depar~ing from the true splrit and scope of ~he lnven-12 tion as set forth in the appended cla~ms.
7 Fig~ 2 is an e~ploded view o~ the printing ele 8 ment sensing mechanismg 9 Fig. 3 is an elevational view of the system shown in Fig~ 1 ~rom the side o the platen;
11 Fig. 4 is an enlarged ~ragmentary sectional view 12 o the sensor sh~wn in Fig, 2~
13 Fig. 5 is an enlarged fragmentary sectional view 14 showing the printing element and a por~ion of the sensor lS shown in Fig. 2;
16 Figo 6 ~ a partial ~eetional vlew sh~w~ng ~he 17 adjustable mounting for the ~ensor o~ Fig~ 2;
18 Figo 7 is a sectional view taken al~ng line 7~7 of 19 Fig~ 6; and Fig. 8 is a blQck diagr~m of ~ eedback loop for 21 controIling the printing element.
22 Detailed Descript _n of a Pr_ferred Embodiment 23 A portion of a printer or typewri~er as shown in 24 Fig. 1 includes a print wheel 10 mounted on a carriage 12 which is adapted to move in a direction parallel with the 26 axis of a platen (not ~h~wn) so as ~o posi~ion the print 27 wheel 10 at various po$itions along a prînt receiving medi-28 um. As the carriage 12 is moved, the print wheel lO is ro~
29 tated by a rotary stepper motor 14 mounted on the carriage 12.
31 The motor 14 comprises a rotor integrally ~vrmed 32 with the printing element or wheel 10 and a stator comprising ~ 5 --6~
a first excited portion 16 and a second unexcited portion 18.
The excited portion 16 includes windings 20 associated with various poles or phases of the stepper motor 14. Additional details of the rotary stepper motor and the wheel 10 are disclosed in copending application Serial ~o. 303,683, assigned to the assignee of this invention.
As also shown in Fig. 1, the carriage 12 for the print wheel 10 is coupled to and driven by a passive slider (not shown) of a high performance linear stepper motor in-cluding a stator having an active portion 22 and a passive portion 24 so as to define a stator-to-stator air gap 26.
The active portion 22 of the stator is energized by windings 28 located at each of the pole positions 30 which extend along the length of the stator 26. Further details concern-ing the high performance linear stepper motor may be found in Canadian Patent No. 1,115,808, assigned to the assignee -~ of this invention.
The carriage 12 is supported on the stator of the linear stepper motor by means of roller bearings 32 and other bearings disclosed in the aforesaid patent no. 1,115,808.
Bracket 34 associated with one such bearing is disclosed in Fig. 1.
Referring to Fig. 3, the printing element or print wheel 10 referred to with respect to Fig. 1 comprises a hub 36 which supports a plurality of radially extending, flexi-ble beams 38 which are terminated at the radial outer ex-tremities thereof by character elements which are mounted on character slugs 40. Rotor elements 42 are inserted in the hub 3~ so as to be integrally formed with the print wheel 30 10. The character slugs 40 are impacted by a hammer (not ~ ~ 1 40 ~
1 shown~ SQ as ~o flex or deform ~he beams and drive ~he 2 character elements in~o ~ontact with an ink ribbon which in 3 turn eontacts the copy medium supported by the platen.
4 In accordance with this inventiona the position of the print wheel 10 is sensed and determined by dircctly and 6 op~ically sensing the beams 38 and the spaces therebetween, 7 More particularly, optical sensor means 44 ls provided a3 8 shown in Fig. 1 and Fig. 4 or sensing the variation in 9 light as the relatively opaque beams 38 and the intermadiate transpsrent spaces or openings rotateO
11 As bes~ shown in Figo 4, the sensor means 44 com-12 prises a bracket 46 through which the beams 38 and the 13 character slugs 40 of the print wheel 10 pass as the print 14 wheel 10 rotates. One side 48 of the bracket 46 carries a light emit~ing means 50 and the other side o~ the bracket 16 46 carries light detector means 54 As best shown in Figs~
17 2 and 5, the light emitting means may, in order to increase 18 reliability, comprise a first plurality of light sources 56 19 such as light emitting diodes and a first plurality o~ light detecting means such as a photo diode one of which is only 21 partially shown. The equal spaces between the first plu-22 rality of light sources and the fir3t plurality of light 23 detectors substantially corresponds with ~he equal spaces 24 between pairs of beams 38, i.e~, space between every other pair of beams 38. As also shown in Figso 2 and 5, the 2~ light emitting means further comprises a second plurality of 27 llght sources 58 and a second plurali~y of light detectors 28 no~ shown. The space between the first plurality 56 and ~he 29 second plurality 58 differs from the spacing between the light sources and detectors within ~he first plurality 56 31 and the second plurality 58 so as to generate signals pro~
32 viding information as to the direction or rotation of the print wheel 10. The sensor 44 includes an additional light source 61 and a detector 62 for sensing coded openings 59 carried by the print wheel 10 as described in Canadian Patent ~o. 1,096,802, which is assigned to the assignee of this invention.
By sensing the position of the print wheel 10 directly from the beams 38 and the openings therebetween, the position of the character elements mounted on the slugs 40 may be assured. Moreover, the mechanism for sensing the position of the character elements is greatly simplified.
In accordance with another important aspect of the invention, the sensor 44 is mounted for adjustment such that the light emitting means 50 (i.e., the pluralities 56 and 58 of light sources) and the light detecting means (i.e~, the first and second plurality of light detectors) may be moved along an arcuate path substantially concentric with the character element. In this connection, the bracket ~4 as shown in Figs. 2 and 4-6 is attached to a supp~rt 60 which is in turn slidably mounted on a member 62 including a track 64. The member 60 as shown in Fig. 6 includes a slot 66 formed by portions 68 and 70 which is adapted to receive the track 64 and a spring member 72 as shown in Figs. 2 and 6.
The spring 72 forces the track outwardly against the wall of the portion 70 which is arcuately formed so as to conform with the track 64 and define the arcuate path of adjustment.
Adjustment is accomplished by means of a screw 74 as best shown in Figs. 2 and 7 which threadedly engages a sleeve 76 which is carried by and secured to the support member 60. By fixing the head position of the screw 74 by means of a pin 7~3 as best shown in Figs. 2 and 7, the sleeve or nut 76 is forced to rise or descend as the screw 74 is ,~, ~ ,.
140~68 turned thereby raising or lowering the support member 60 along the defined arcuate path as well as the bracket 44.
An additional screw 80 and an associated nut 82 are utilized to lock the bracket 44 in place. In this connection, a slot 84 as best shown in Figs. 2 and 6 is provided in the support member 60. With the screw 80 and the nut 82 loose, the sup-port member 60 may slide relative to the screw 80 and the nut 82 thereby permitting adjustment of the bracket 44.
Fig. 8 discloses a block diagram of a feedback sensor system utilizing the output of the sensor 44. As shown, a position determining circuit 90 utilizes the output from the sensor 44 to generate a signal representing the position of the print wheel. The output from the position-ing determining circuit 90 is then applied to motor drive circuitry 92. The motor drive is utilized to energize the winding 20 as shown in Fig. 1 of the stator 94 which is mag-netically coupled to the rotor 96 integrally formed with the print wheel 10 so as to control the stopping position of the print wheel 10. Of course, the beams of the print wheel which are integrally formed with the rotor 96 are directly and optically coupled to the sensor 44 as described in the foregoing. Details concerning the position determining cir-cuit 90 and the motor drive circuit 92 may be found in co-pending Canadian application serial no. 310,368, filed August 30, 1978, assigned to the assignee of this invention.
In accordance with another impDrtant aspect of this invention, the frequently used handle or flag 100 shown in Fig. 3 which extends radially outwardly from the hub 36 includes a plurality of openings 102 having spaces therebe-tween which are substantially identical to the circumferen-tial width of the beams 38. This allows the feedback . -- g _ ~4~ 6~3 !
1 control of thQ printing elemen~ 10 even when the handle 100 2 is in the vicinity of the sensor 44~ In other words, the 3 motor is capable of stopping at a plurality of positions 4 with the handle generally in the printing position. Of oourse, the handle can be eliminated w~th beams 38 substi-6 tuted in order to fill thP area of the handle lOQ ~o as no~
7 to interfere wit~ the feedback.
8 Although de~ails of a particular preferred embodi-9 ment of the invention have been shown and de~cribed, it will be unders~ood that various modifications may be made wi~h-11 out depar~ing from the true splrit and scope of ~he lnven-12 tion as set forth in the appended cla~ms.
Claims (9)
1. A printing system for positioning character ele-ments including a rotary stepper motor stator comprising a plurality of windings associated with various phases of said motor, a character wheel having a hub carrying a plurality of magnetic rotor elements, a plurality of beams extending rad-ially outwardly from the hub and character elements supported by the radial outer extremity of the beams in a substantially circular array in fixed relationship with respect to said rotor elements, feedback means for sensing the position of said character wheel, means for rotatably driving and stopping said character wheel in response to the sensed position so as to stop a particular character element at a predetermined position, said character wheel having a substantially uniform pattern of beams and spaces around the entire circumference of said character wheel radially outwardly from said hub, said feedback means comprising means for directly sensing said patt-ern, and means for driving the windings associated with said various phases of said stepper motor in response to said-sensing.
2. The system of claim 1 wherein said means for direct-ly sensing comprises optical sensor means.
3. The system of claim 2 wherein said optical sensor means comprises light emitting means located on one side of said character wheel for directing light between and at said beams and light detecting means located on the opposite side of said character wheel for detecting said light.
4. The system of claim 3 wherein said light emitting means comprises a first plurality of light sources having spaces therebetween substantially equal to the spaces be-tween said beams of said optical sensor means and said light detecting means comprises a first plurality of light detectors having spaces therebetween substantially equal to the spaces between said light sources.
5. The system of claim 4 wherein said light emitting means comprises a second plurality of said light sources and a second plurality of said light detectors, the spaces between said light sources of said second plurality and said light detectors of said second plurality being equal to the spaces between said light sources of said first plurality and said light detectors of said first plurality, the distance be-tween said first plurality and said second plurality differ-ing from said spaces.
6. The system of claim 3 including adjustable means for moving said light emitting means and said light detecting means in an arcuate path substantially concentric with said character wheel.
7. The system of claim 1 wherein said character wheel comprises a handle portion extending radially outwardly be-tween a pair of said beams a substantially lesser distance than said character elements, said handle portion including a plur-ality of openings having circumferential spacing substantially corresponding to the spaces between said beams and forming part of said pattern, said sensing means sensing the open-ings in said handle.
8. A method of operating a printing system comprising a rotary stepper motor including a stator having a plurality of windings associated therewith, a character wheel including a hub carrying a plurality of rotor elements and a substantially uniform pattern of beams and spaces around the entire circum-ference of the wheel radially outwardly from said hub, said pattern including, character elements supported at the radial outer extremities of said beams and hammer means adapted to strike said character elements, said method comprising:
directing light at said beams and spaces as said character wheel rotates; directly sensing the variation in light as said beams pass therethrough for determining the position of said character wheel, driving the windings associated with said phases of said stator in response to the sensed light variations, stopping the character wheel in response to the determined position of said character wheel as sensed by the variation in light; and actuating the hammer means to strike a character element.
directing light at said beams and spaces as said character wheel rotates; directly sensing the variation in light as said beams pass therethrough for determining the position of said character wheel, driving the windings associated with said phases of said stator in response to the sensed light variations, stopping the character wheel in response to the determined position of said character wheel as sensed by the variation in light; and actuating the hammer means to strike a character element.
9. The method of claim 8 wherein said character wheel further comprises a handle portion extending radially outward ly between a pair of said beams a lesser distance than said character elements, said handle portion including a plurality of windows therein forming part of said pattern, said method further comprising the step sensing the variation in light through said windows for determining the position of said char-acter wheel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000415136A CA1168178A (en) | 1977-09-14 | 1982-11-08 | Method and apparatus for sensing the position of a character printing element |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US83335177A | 1977-09-14 | 1977-09-14 | |
| US833,351 | 1977-09-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1140068A true CA1140068A (en) | 1983-01-25 |
Family
ID=25264179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000310367A Expired CA1140068A (en) | 1977-09-14 | 1978-08-30 | Method and apparatus for sensing the position of a character printing element |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5454717A (en) |
| AU (1) | AU528257B2 (en) |
| BE (1) | BE870432A (en) |
| BR (1) | BR7805979A (en) |
| CA (1) | CA1140068A (en) |
| CH (1) | CH642003A5 (en) |
| DE (1) | DE2839022A1 (en) |
| FR (1) | FR2403195A1 (en) |
| GB (1) | GB1604578A (en) |
| IT (1) | IT1098243B (en) |
| MX (1) | MX5727E (en) |
| NL (1) | NL7809392A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55148125A (en) * | 1979-05-07 | 1980-11-18 | Oiles Ind Co Ltd | Device and method for making rolled laminated tube |
| IT1199878B (en) * | 1985-04-22 | 1989-01-05 | Olivetti & Co Spa | REVOLVING CHARACTER ORGAN AND ITS SELECTION DEVICE FOR A PRINTING UNIT OF WRITING MACHINES |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3566782A (en) * | 1968-08-21 | 1971-03-02 | Singer Co | Address synchronizer |
| CA1039217A (en) * | 1974-07-01 | 1978-09-26 | Willy J. Grundherr | Rotary wheel printing system |
| CA1121751A (en) * | 1977-06-24 | 1982-04-13 | Dan W. Matthias | Character print wheel with drive elements |
| GB1604577A (en) * | 1977-09-14 | 1981-12-09 | Exxon Research Engineering Co | Coded printing element and apparatus for use thereof |
| US4149808A (en) * | 1977-09-14 | 1979-04-17 | Exxon Research & Engineering Co. | Linear drive for a printing apparatus |
-
1978
- 1978-05-26 GB GB23099/78A patent/GB1604578A/en not_active Expired
- 1978-08-15 AU AU38905/78A patent/AU528257B2/en not_active Expired
- 1978-08-24 MX MX787350U patent/MX5727E/en unknown
- 1978-08-25 IT IT27063/78A patent/IT1098243B/en active
- 1978-08-30 CA CA000310367A patent/CA1140068A/en not_active Expired
- 1978-08-30 FR FR7825077A patent/FR2403195A1/en not_active Withdrawn
- 1978-09-07 DE DE19782839022 patent/DE2839022A1/en not_active Withdrawn
- 1978-09-13 BR BR7805979A patent/BR7805979A/en unknown
- 1978-09-13 BE BE190442A patent/BE870432A/en not_active IP Right Cessation
- 1978-09-14 NL NL7809392A patent/NL7809392A/en not_active Application Discontinuation
- 1978-09-14 CH CH961878A patent/CH642003A5/en not_active IP Right Cessation
- 1978-09-14 JP JP11244378A patent/JPS5454717A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CH642003A5 (en) | 1984-03-30 |
| BE870432A (en) | 1979-03-13 |
| JPS5454717A (en) | 1979-05-01 |
| MX5727E (en) | 1983-12-29 |
| NL7809392A (en) | 1979-03-16 |
| AU3890578A (en) | 1980-02-21 |
| AU528257B2 (en) | 1983-04-21 |
| IT1098243B (en) | 1985-09-07 |
| GB1604578A (en) | 1981-12-09 |
| IT7827063A0 (en) | 1978-08-25 |
| FR2403195A1 (en) | 1979-04-13 |
| DE2839022A1 (en) | 1979-03-22 |
| BR7805979A (en) | 1979-05-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |