Claims
- 1. An ink-jet printer for printing onto a print medium characterized as a thin layer with opposed first and second surfaces, comprising:
- a printhead for ejecting ink droplets onto said first print medium surface in a controlled fashion, said printhead being disposed above said first surface of said print medium at a print area;
- means for advancing said print medium to said print area during print operations; and
- a print heater means for heating a portion of said medium disposed at said print area during said print operations to cause accelerated drying of said ink deposited on said medium, said heater means comprising
- a radiant heat source for generating radiant heat energy, said radiant heat source comprising a heater element energized by low voltage electrical signals to generate the radiant energy and means for generating said low voltage electrical signals;
- means for directing said radiant heat energy onto a portion of said second surface of said print medium disposed at said print area; and
- means positioned between said heater means and said second surface of said medium for supporting said print medium at said print area while permitting said radiant heat to be transmitted from said heater means to said second surface, said supporting means permitting little if any conductive heat transfer to said second surface.
- 2. The printer of claim 1 wherein said directing means comprises a reflector defining an elongated heater cavity disposed under said second surface of said print medium at said print area along a lateral extent of such print medium, and said radiant heat source is disposed within said cavity.
- 3. The printer of claim 2 wherein said reflector is characterized by a highly reflective cavity-defining surface, said surface for reflecting radiant heat energy generated by said heater element toward said second surface.
- 4. The printer of claim 1 wherein said heat source further comprises a quartz tube, and said heater element comprises a wire element disposed within said tube.
- 5. The printer of claim 1 wherein said radiant heat source further comprises a temperature-controlled heater drive circuit, comprising a temperature sensor for sensing a temperature level adjacent said heat source and providing a temperature level signal, and control circuit means responsive to said temperature level signal for energizing said wire element according to a predetermined power setting.
- 6. The printer of claim 5 wherein said temperature sensor comprises a temperature-sensitive resistor element disposed adjacent an opening formed in a base of said cavity-defining surface, wherein an electrical resistance of said element indicates said temperature level.
- 7. The printer of claim 1 wherein said means for generating said low voltage signals comprises a DC power supply for supplying a low DC voltage signal, and a pulse width modulator for modulating said low voltage signal to provide a square wave signal of variable pulse width, thereby providing a selectable radiant energy power setting for said radiant heat source.
- 8. The printer of claim 7 wherein said low DC voltage signal is a nominal 35 vDC signal.
- 9. The printer of claim 7 wherein said means for generating said low voltage signals further comprises constant power closed loop control circuit for applying constant electric power to said radiant heat source during a given operating period, said control circuit comprising means for providing a modulator control signal to said pulse width modulator to control said pulse width.
- 10. The printer of claim 9 wherein said heater element includes a resistive wire element, and said means for generating said low voltage signals further comprises a low pass filter for filtering said square wave signal, changing said square wave pulse width modulated signal into an average DC signal passed to said heater element, thereby preventing oscillations at said heater element.
- 11. The printer of claim 10 wherein said constant power control loop includes a current sense circuit for sensing a current level drawn through said heater element and a voltage sense circuit for sensing a voltage developed across said heater element, and a controller responsive to said current and voltage sense circuits for monitoring an average electrical power applied to said heater element, said controller adjusting said pulse width of said pulse width modulated signal to maintain constant heater drive power during said given operating period.
- 12. The printer of claim 1 wherein said means for generating said low voltage signals further comprises constant power closed loop control circuit for applying constant electric power to said radiant heat source during a given operating period.
- 13. The printer of claim 12 wherein said constant power control loop includes a current sense circuit for sensing a current level drawn through said heater element and a voltage sense circuit for sensing a voltage developed across said heater element, and a controller responsive to said current and voltage sense circuits for monitoring an average electrical power applied to said heater element, said controller adjusting said means for generating said low voltage signals to maintain constant heater drive power during said given operating period.
- 14. An ink-jet printer for providing a heated print area to facilitate drying of ink deposited on a print medium during print operations, said print medium comprising a thin layer with first and second opposed surfaces, said printer comprising:
- an inkjet cartridge for ejecting ink droplets onto said print medium in a controlled fashion, said cartridge disposed above said first surface of said print medium at a print area and arranged for lateral movement across a lateral extent of said print medium during said printing operations;
- means for advancing said print medium to said print area in a direction transverse to a direction of said lateral movement of said cartridge to position said print medium in relation to said cartridge for said print operation;
- radiant print heater means for directing radiant heat at a portion of said second surface of said print medium at said print area and along said lateral extent of said medium to heat a portion of said print medium disposed at said print area and thereby causes accelerated drying of said ink ejected onto said first surface; and
- means positioned between said heater means and said second surface of said medium for supporting said print medium at said print area while permitting transfer of said radiant heat from said heater means to said second surface, said supporting means permitting little if any conductive heat transfer to said second surface.
- 15. The printer of claim 14 wherein said heater means comprises an elongated heater element for converting low voltage electrical energy into radiant heat, and a reflector defining a reflector cavity having an elongated opening extending along said lateral extent of said medium disposed at said print area, said heater element disposed within said reflector cavity, wherein said reflector comprises means for reflecting radiant heat energy generated by said heater element toward said elongated reflector opening.
- 16. The printer of claim 15 wherein said heater element comprises a wire element energized by low voltage electrical signals.
- 17. The printer of claim 16 wherein said heater element further comprises a quartz tube, and said wire element is disposed within said tube.
- 18. The printer of claim 14 wherein said means for supporting said print medium at said print area provides support of said medium at said cavity opening.
- 19. The printer of claim 14 wherein said radiant print heater means further comprises a temperature-controlled heater drive circuit, comprising a temperature sensor for sensing a temperature level of said heater means and providing a temperature level signal, and a control circuit means responsive to said temperature level signal for controlling an amount of electrical power driving said heater means.
- 20. The printer of claim 19 wherein said temperature sensor comprises a temperature-sensitive resistor element, wherein a resistance of said element indicates said temperature level.
- 21. The printer of claim 14, further comprising means for generating low voltage signals to energize said heater means, and wherein said means for generating said low voltage signals comprises a DC power supply for supplying a low DC voltage signal, and a pulse width modulator for modulating said low DC voltage signal to provide a square wave of variable pulse width, thereby providing a selectable radiant energy power setting for said heater means.
- 22. The printer of claim 21 wherein said low DC voltage signal is a nominal 35 vDC signal.
- 23. The printer of claim 21 wherein said means for generating said low voltage signals further comprises a constant power closed loop control circuit for applying constant electric power to said radiant print heater means during a given operating period, said control circuit comprising means for providing a modulator control signal to said pulse width modulator to control said pulse width.
- 24. The printer of claim 23, wherein said heater means includes a resistive wire element, and said means for generating said low voltage signal further comprises a low pass filter for filtering said square wave signal, changing said square wave pulse width modulated signal into an average DC signal passed to said heater means thereby preventing oscillations at said heater means.
- 25. The printer of claim 24 wherein said constant power control loop includes a current sense circuit for sensing a current level drawn through said heater element and a voltage sense circuit for sensing a voltage developed across said heater element, and a controller responsive to said current and voltage sense circuits for monitoring an average electrical power applied to said heater element, said controller adjusting said pulse width of said pulse width modulated signal to maintain constant heater drive power during said given operating period.
- 26. The printer of claim 14 further comprising means for generating low voltage signals to energize said heater means, said generating means comprising a constant power closed loop control circuit for applying constant electric power to said radiant print heater means during a given operating period.
- 27. The printer of claim 26 wherein said constant power control loop includes a current sense circuit for sensing a current level drawn through said heater means and a voltage sense circuit for sensing a voltage developed across said heater means, and a controller responsive to said current and voltage sense circuits for monitoring an average electrical power applied to said heater means, said controller adjusting said means for generating said low voltage signal to maintain constant heater drive power during said given operating period.
RELATED APPLICATIONS
This application is a continuation-in-part of application Ser. No. 07/876,924, filed May 1, 1992, HEATER BLOWER SYSTEM IN A COLOR INK-JET PRINTER, by B. Richtsmeier et al.
This application is related to application Ser. No. 08/056,288, filed 4/30/93, Attorney Docket No. 1093135-1, entitled AIRFLOW SYSTEM FOR INK-JET PRINTER, by W. Schwiebert et al.; application Ser. No. 08/056,229, filed 4/30/93, Attorney Docket No. 1093141-1, IMPROVED MEDIA CONTROL AT INK-JET PRINT ZONE, by R. R. Giles et al.; application Ser. No. 08/055,609, filed 4/30/93, Attorney Docket No. 1093142-1, DUAL FEED PAPER PATH FOR INK-JET PRINTER, by R. R. Giles et al.; application Ser. No. 08/056,449, filed 4/30/93, Attorney Docket No. 1093151-1, MULTI-PURPOSE PAPER PATH COMPONENT FOR INK-JET PRINTER, by G. G. Firl et al.; application Ser. No. 08/056,039, filed 4/30/93, Attorney Docket No. 1093155-1, PAPER PRECONDITIONING HEATER FOR INK-JET PRINTER, by W. Schwiebert et al.; and application Ser. No. 07/876,939, filed May 1, 1992, AIRFLOW SYSTEM FOR THERMAL INK-JET PRINTER, by T. Russell et al.
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Continuation in Parts (1)
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876924 |
May 1992 |
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