EP0107501A2 - Indicateur de position pour imprimante rapide - Google Patents

Indicateur de position pour imprimante rapide Download PDF

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Publication number
EP0107501A2
EP0107501A2 EP83306463A EP83306463A EP0107501A2 EP 0107501 A2 EP0107501 A2 EP 0107501A2 EP 83306463 A EP83306463 A EP 83306463A EP 83306463 A EP83306463 A EP 83306463A EP 0107501 A2 EP0107501 A2 EP 0107501A2
Authority
EP
European Patent Office
Prior art keywords
encoder
light
carriage
platen
printer
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.)
Withdrawn
Application number
EP83306463A
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German (de)
English (en)
Other versions
EP0107501A3 (fr
Inventor
Royden C. Sanders, Jr.
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
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Individual
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Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0107501A2 publication Critical patent/EP0107501A2/fr
Publication of EP0107501A3 publication Critical patent/EP0107501A3/fr
Withdrawn legal-status Critical Current

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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
    • B41J19/00—Character- or line-spacing mechanisms
    • B41J19/18—Character-spacing or back-spacing mechanisms; Carriage return or release devices therefor
    • B41J19/20—Positive-feed character-spacing mechanisms
    • B41J19/202—Drive control means for carriage movement
    • 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
    • B41J19/00—Character- or line-spacing mechanisms
    • B41J19/18—Character-spacing or back-spacing mechanisms; Carriage return or release devices therefor
    • B41J19/20—Positive-feed character-spacing mechanisms
    • B41J19/202—Drive control means for carriage movement
    • B41J19/205—Position or speed detectors therefor
    • 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
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/22—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of impact or pressure on a printing material or impression-transfer material
    • B41J2/23—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective application of impact or pressure on a printing material or impression-transfer material using print wires
    • B41J2/235—Print head assemblies

Definitions

  • the present invention relates to a position indicator for ascertaining the transverse position of a print head or other device relative to a surface, e.g. of a sheet or document such as, the transverse location of the dot matrix print head of a high speed printer relative to a sheet of paper upon which indicia (characters, graphics and the like) are formed by the operation of the print head.
  • a position indicator for ascertaining the transverse position of a print head or other device relative to a surface, e.g. of a sheet or document such as, the transverse location of the dot matrix print head of a high speed printer relative to a sheet of paper upon which indicia (characters, graphics and the like) are formed by the operation of the print head.
  • a position indicator for ascertaining the transverse position of a print head or other device relative to a surface, e.g. of a sheet or document such as, the transverse location of the dot matrix print head of a high speed printer relative to a sheet of paper upon which
  • position indicator in the context of locating the transverse position of a print head relative to a platen or, more precisely, a sheet of paper positioned adjacent the platen, in the context of a printer of the type disclosed in United States Letters Patent 4,159,882.
  • position indicator has use in other types of printers and in other types of apparatus.
  • a print head is moved transversely (i.e., parallel to the axis of the printer platen) across the paper upon which characters are to be printed by a stepper motor though a capstan and cable arrangement.
  • the stepper motor serves not only as the drive mechanism but because of its position orientation with respect to timed pulses, also serves as the determinant of the transverse position (or location) of the print head relative to the paper. Stepper motors are relatively expensive and they introduce transient mechanical forces into the system, which must be carefully controlled in order to obtain accurate positioning.
  • a commonly used method of using an optical sensor is to mount a sensor like a Hewlett Packard HEDS 5000 series optical sensor on the horizontal slew motor.
  • This suffers the disadvantage that the motor axis oscillates very violently upon turnaround causing great complication in the quadrature detection circuits needed in order to prevent loss of registration.
  • this cable since this cable must be attached to the print head carriage near the center of mass, bearing tolerance introduces appreciable errors as to where the print head will print on the paper.
  • the position locating function of the stepping motor can also be provided by an optical fence system employing light, but any such system must overcome a number of problems common to optical fence systems in order to obtain sufficient resolution to effect the accuracy required.
  • an optical fence system uses a bar pattern where the bars alternate between being highly opaque and highly transmissive of light.
  • the spacing between successive bars of the same kind can be referred to as the wavelength.
  • the bar pattern can be reflective, where the bars.alternate between being highly absorptive and highly reflective of light.
  • Another method employs a transmissive fence operating in conjunction with a second transmissive fence of identical geometry. Motion of the second fence relative to the first shifts the phase angle of the second pattern with respect to the first.
  • the two transmissive portions are in direct alignment, half of the source light is transmitted through the transmissive portions of both fences, and is available for impinging on a detector.
  • the transmissive portions of the first fence as a consequence being aligned with opaque portion of the second fence, all of the source light is blocked by opaque regions, and hence the light is prevented from impinging on a detector.
  • the advantage of this type of fence is that the total amount of light available to the detector is the sum of the light through several transmissive bars when so aligned, and hence the ratio of light to dark intensities is significantly better than is the case with a single slit.
  • the dual fence system begins to encounter significant problems as attempts are made to increase resolution. Specifically, as the pattern wavelength decreases to where the spacing between the fixed and movable bar patterns is a significant part of the pattern wavelength, scattering by refracted light increases the dark intensity (amount of light impinging on the detector when the patterns are aligned opaquely), thereby reducing the light to dark ratio. Physical variations and vibrations of the mechanical system cause amplitude modulation of the detected signal, making recognition difficult. Dust and dirt, grease and other contaminants increase scattering and absorb light, thereby reducing the light to dark ratio. All of these problems make achieving high resolution with conventional techniques difficult. Some of the problems can be overcome with careful design, close tolerance, etc., but the economics of the market place impose a limit on how much can be done.
  • the object of the present invention to provide a highly accurate locator mechanism for the printers that does not suffer the above disadvantages and which provides a less expensive and reliable mechanism. It is a further object of the invention to provide such a mechanism which permits other than stepper motors (e.g. a D.C. motor) to be used for carriage traverse.
  • stepper motors e.g. a D.C. motor
  • apparatus having first and second members adapted for relative movement therebetween, and a drive means for producing said relative movement, a position indicator for indicating the relative position of said first and second members, said position indicator comprising an optical position encoder means mounted for rotation relative to said first member comprising, a position responsive means separate from said drive means adapted to transmit said movement from said second member to rotate said optical position encoder means in synchronism therewith, said encoder means having a pattern of detectable indicia, and a detector responsive to said indicia to provide a signal indicative of the rate and amount of said rotation of said encoder means.
  • a printer having an elongate platen and a print head carriage adapted for relative movement therebetween longitudinally of the platen, means for driving said carriage, a position indicator, for ascertaining the position of said carriage longitudinally of said platen, comprising an optical position encoder rotatably mounted on an axis fixed longitudinally of said platen, a carriage position responsive means connected to said carriage immediately adjacent said print head and said encoder to transmit said relative movement to said encoder to rotate said encoder in synchronism with said relative movement, said position responsive means being separate from said carriage driving means said encoder having a pattern of detectable indicia, and a detector responsive to said indicia to provide a signal indicative of said position.
  • the position responsive means is preferably a substantially non-extensible cable connected to the carriage closely adjacent to the printing location of a print head mounted on the carriage, thereby faithfully to transmit relative movement of the printing (pin) location and the platen.
  • the encoder is in the form of a disc and the pattern of indicia consists of thin stripes (or bars) oriented radially to the axis of the disc.
  • the stripes are alternately transparent and opaque.
  • a light source directs light upon the pattern to provide a transmitted light pattern comprising a plurality of intense light regions (photon packets) separated by regions of substantially zero light intensity, there being relative movement between the disc and the light source so that each region of the plurality of regions changes from intense light (i.e., light) to substantially zero light (i.e., dark) as a function of distance.
  • a lens is positioned -to focus light from the source onto the pattern.
  • a further lens is positioned to receive the transmitted light pattern and serves to focus the light pattern.
  • a reticle is positioned to receive the focused light pattern from the disc.
  • the reticle consists of a short strip with a pattern of thin stripes oriented perpendicular to the annular extension of the strip. These thin stripes are alternately transmissive and non-transmissive (either absorptive or reflective).
  • magnification ratio of the lens system is unity, the spatial wavelength of the thin stripes of the reticle are the same as that of the disc. It will be recognized that other embodiments are possible using different magnification ratios in the lens system, where the wavelength of the reticle pattern would be scaled suitably in accordance with the magnification ratio of the lens such that the resultant light pattern impinging on the reticle would have the same spatial wavelength as that of the reticle.
  • the action of the reticle is such as to permit light that is aligned with its transmissive areas to pass through it, and to block light that is aligned spatially with its reflective areas.
  • the transmitted light from the disc is aligned spatially with the transmissive region of the reticle, the maximum amount of light possible passes through the reticle.
  • the minimum amount of light passes through the reticle.
  • a quadraphase detector is mounted behind the reticle to detect the total amount of light coming through the reticle. The detector provides a signal that can be analyzed to indicate transverse position relative to the light source.
  • the focused light, so analyzed consists of at least several of the intense light regions (photon packets) which combine or average in the detector means to generate said signal.
  • the output of the Quadraphase Detector is processed to provide digital direction and video signals representing the direction of carriage traverse and the position of the carriage relative to the platen.
  • the resulting signals are fed to a microprocessor which keeps a 16 bit register of the horizontal position of the print head.
  • the microprocessor measures the velocity (by measuring the number of video pulses received in the time of flight of print head) and acceleration by measuring the difference in successive velocity measurements. As an alternative this could be done by hardware.”
  • the microprocessor uses the video pulses to unload a pin fire buffer and generate firing pulses for the print head and uses the velocity and acceleration to modify the unloading address to compensate for the time of flight.
  • a print head carriage 1 upon which a dot matrix print head 2 is mounted is slidably supported on horizontal support rods 3 and 4 along which it is moved by a drive belt 5 which is driven by a D.C. motor 6 to produce the desired transverse motion of the print head relative to platen 7.
  • the dot matrix print head 2 has print head pins 8, the selective operation of which creates a printed image on paper 9 by means of a ribbon 10.
  • a carriage position responsive cable 11 is affixed to the carriage by means of two posts 12 located closely adjacent the pin location in the print head.2. This ensures faithful transmission of print location movement relative to the paper 9 regardless of tolerances and wear in the carriage bearings on the support rods.
  • the character position responsive cable extends around an idler pulley 13, mounted for rotation on the printer chassis at one end of the carriage traverse along the platen 7, from one pin 12 to an optical disc encoder 14 mounted for rotation at the other extreme of the traverse of the print head carriage along the platen.
  • the optical disc 14 carries a plurality of indicia in the form of equally spaced radial opaque lines with the spaces between the lines being transparent.
  • belts and cables as used herein are interchangeable and that other flexible drive elements, for example, chains or other multiple link elements, could be substituted for the belts or cables of the present invention without departing from the inventive concept.
  • the carriage position responsive cable 11 drives only the idler pulley 13 and the optical disc encoder 14 there is very little inertia and a very light cable can be used without producing error causing stretch thereof.
  • the optical disc encoder will faithfully measure the horizontal (transverse) position of the print head relative to the platen and paper supported on that platen.
  • both the idler pulley 13 and the optical disc encoder 14 are mounted for rotation on the relatively rigid platen structure extrusion 15 which is mechanically isolated by vibration isolaters 16 from the structure support the drive D.C. motor 6.
  • the optical disc encoder 14 is a pulley which has a peripheral groove to engage cable 11.
  • the pulley is made of clear plastic with the plurality of equi-spaced radial opaque lines 17 (optical fence) being sandwiched in the center of the pulley.
  • the pulley is mounted on a shaft 18 supported for rotation relative to the platen extrusion 15 by means of a bearing 19.
  • the optical detector and transmitter 20 includes a light transmitter 21, in the form of a light emitting diode (LED) and a lens 22 adapted to focus the light emitted by the LED onto the radial lines 17.
  • LED light emitting diode
  • a lens 23 focuses light received by way of the spaces between the plurality of line 17 from the LED onto a quadraphase reticle 24 which screens the light so received onto quadraphase detectors 25 which in turn provide video output signals indicative of the light received and consequently the transverse position of the print head carriage 1 relative to platen 7.
  • radial lines 17 are shown in Figure 4 and that these radial lines in fact are equispaced throughout the annular area of the optical disc encoder in which they are shown.
  • the reticle 24 which is disposed at the image plane, has a reticle pattern of transparent regions or stripes (e.g., slots) separated by opaque regions that correspond both in size (i.e., width) and position to the light regions and the regions of the transmitted light pattern.
  • a reticle pattern of transparent regions or stripes e.g., slots
  • opaque regions that correspond both in size (i.e., width) and position to the light regions and the regions of the transmitted light pattern.
  • there is one-to-one correspondence between the widths but the reticle pattern and the transmitted pattern can have other relationships, depending on the magnification ratio of the lens system.
  • the light pattern is transmitted through the reticle when the light regions register with the transparent regions and the light pattern is blocked when the light regions register with the opaque regions.
  • the quadraphase detectors 25 receive the total light transmitted through the reticle; the detector converts the light energy to a current that can be analyzed to indicate transverse position of the print head relative to the platen.
  • the light so analyzed consists of at least several of the intense light regions which combine or average in the detector to generate the voltage signal.
  • the detector in the sensor assembly is a detector pair.
  • the reticle is a split reticle with regions in spatial quadrature to one another to sense respectively the zero-phase light and 90°-phase light (with respect to reticle stripe spacing) respectively. It will be observed that the regions are spatially in quadrature with one another, that is, regions of one part of the reticle are displaced or offset to the right of the regions of its other part one-half the width of each region and hense collect their maximum light at a place that differs from the place that the regions of the other collect maximum light.
  • the O-phase light is sensed by one detector (e.g., a light sensitive diode) to provide a voltage signal which is
  • the reticle is disposed immediately adjacent (i.e., juxtaposed to the detector(s)). It should be noted that the reticle can be fabricated on the surface of the detector; the close proximity of the reticle to the detector greatly reduces light scattering to the detector, which permits a high ratio of light to dark signal from the detector even at very short pattern wavelengths. Having a split reticle with the two reticles thereof offset from one another in the direction of travel of the disc relative to the light source-sensor permits the circuit illustrated in Fig.
  • the offset of the reticle parts typically is one-fourth line width, that is, 90 spatial degrees. Accordingly the two reticles forming the split reticle are separated in the direction (i.e., in the direction of travel) to occupy discrete locations.
  • Fig. 5 is a schematic of a logic circuit to provide direction and video signals from signals ⁇ 1 and ⁇ 2 , which signals are fed to the circuit on inputs designated ⁇ 1 and ⁇ 2 respectively.
  • Other inputs are 5 volt supplies fed by way of resistors R 1 , R 2 , R 3 and R 4 and a system clock pulse input (SYS CLOCK).
  • SYS CLOCK system clock pulse input
  • the circuit produces a direction signal indicating the direction of traverse of the carriage along the platen and a video signal which under stable conditions of traverse comprises a series of pulses corresponding to the leading and trailing edges of the digital signals ⁇ 2 .
  • a direction signal indicating the direction of traverse of the carriage along the platen
  • a video signal which under stable conditions of traverse comprises a series of pulses corresponding to the leading and trailing edges of the digital signals ⁇ 2 .
  • each signal generated by the Quadraphase Detector produces a single ⁇ 2 digital signal represented by two pulses in the video output.
  • the circuit (U3) operates to omit the second (that associated with the trailing edge of ⁇ 2 ) pulse normally associated in the video signal with that ⁇ 2 signal.
  • the state of the direction signal is changed to reflect the change in direction of traverse.
  • the circuit outputs of direction and video are inputted to a microprocessor.
  • the output of the Quadraphase Detector (the video signal) is inputted to a microprocessor which keeps a 16 bit register of the horizontal position of the print head.
  • the microprocessor measures the velocity (by measuring the number of video pulses received in the time of flight of print head) and acceleration by measuring the difference in two successive velocity measurements. As an alternate this could be done by hardware.
  • the microprocessor uses the video pulses to unload a pin line buffer and generate firing pulses for the print head and uses the velocity and accelaration to modify the unloading address to compensate for the time of flight.
  • the light transmitting arrangements and light detecting arrangements will be placed adjacent one another on the same side of the disc with the detecting arrangements arranged to receive light reflected by the areas between the lines.
  • the optically detectable pattern of indicia could be replaced by a pattern of non-optical indicia (e.g. magnetic, capacitive, structural, deformation, etc.) with associated detector changes without departing from the inventive concept.
  • the disc/pulley could be replaced by a drum peripherally carrying the indicia or other rotatable indicia carrying means etc., also without departing from the inventive concept.

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  • Character Spaces And Line Spaces In Printers (AREA)
EP83306463A 1982-10-27 1983-10-25 Indicateur de position pour imprimante rapide Withdrawn EP0107501A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US43694982A 1982-10-27 1982-10-27
US436949 1982-10-27

Publications (2)

Publication Number Publication Date
EP0107501A2 true EP0107501A2 (fr) 1984-05-02
EP0107501A3 EP0107501A3 (fr) 1985-08-28

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EP83306463A Withdrawn EP0107501A3 (fr) 1982-10-27 1983-10-25 Indicateur de position pour imprimante rapide

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EP (1) EP0107501A3 (fr)
JP (1) JPS59131484A (fr)
CA (1) CA1218263A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6194859B1 (en) * 1999-02-22 2001-02-27 Michael R. Everman X-Y positioner based on X axis motions
GB2356600A (en) * 1999-11-16 2001-05-30 Agilent Technologies Inc An optical navigation unit and method for a printer

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2157187A5 (fr) * 1971-10-21 1973-06-01 Sagem
FR2294852A1 (fr) * 1974-12-18 1976-07-16 Nippon Electric Co Imprimante en serie de type a matrice de points
FR2393355A1 (fr) * 1977-05-31 1978-12-29 Nippon Electric Co Dispositif de commande de position
FR2407077A1 (fr) * 1977-11-01 1979-05-25 Gen Electric Dispositif de compensation du mouvement de la tete d'impression pour une imprimante
GB2012089A (en) * 1978-01-09 1979-07-18 Rank Organisation Ltd Electro-mechanical printing apparatus

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4195938A (en) * 1977-02-09 1980-04-01 Sycor, Inc. Lateral position control means for data printer heads
JPS57103959A (en) * 1980-12-19 1982-06-28 Fuji Xerox Co Ltd Apparatus for driving body and for detecting position thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2157187A5 (fr) * 1971-10-21 1973-06-01 Sagem
FR2294852A1 (fr) * 1974-12-18 1976-07-16 Nippon Electric Co Imprimante en serie de type a matrice de points
FR2393355A1 (fr) * 1977-05-31 1978-12-29 Nippon Electric Co Dispositif de commande de position
FR2407077A1 (fr) * 1977-11-01 1979-05-25 Gen Electric Dispositif de compensation du mouvement de la tete d'impression pour une imprimante
GB2012089A (en) * 1978-01-09 1979-07-18 Rank Organisation Ltd Electro-mechanical printing apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6194859B1 (en) * 1999-02-22 2001-02-27 Michael R. Everman X-Y positioner based on X axis motions
GB2356600A (en) * 1999-11-16 2001-05-30 Agilent Technologies Inc An optical navigation unit and method for a printer
GB2356600B (en) * 1999-11-16 2003-04-30 Agilent Technologies Inc Optical navigation system and method
US6568777B1 (en) 1999-11-16 2003-05-27 Agilent Technologies, Inc. Optical navigation system and method

Also Published As

Publication number Publication date
EP0107501A3 (fr) 1985-08-28
CA1218263A (fr) 1987-02-24
JPS59131484A (ja) 1984-07-28

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