THERMAL TRANSFER PRINTER

Abstract

Thermal transfer printer for selectively transferring a meltable ink material carried on a tape to a substrate intended to receive ink from said tape for printing an image on the substrate, the printer comprising a supply spool for the tape, a take-up spool for the tape, and a printhead between the supply spool and the take-up spool, wherein the supply spool is driven by a supply motor and the take-up spool is driven by a take-up motor, and that the printer comprises a spool drive controller which is configured to energize the supply motor and the take-up motor so as to arrange that the tape is un-wound from the supply spool and wound onto the take-up spool, wherein the spool drive controller is embodied with field oriented control driving the supply motor and the take-up motor so as to continuously and uninterruptedly control motor torque of said motor's.

Claims

1. Thermal transfer printer for selectively transferring a meltable ink material carried on a tape (7) to a substrate intended to receive ink from said tape (7) for printing an image on the substrate (9), the printer comprising a supply spool (1) for the tape (7), a take-up spool (2) for the tape (7), and a printhead (18) between the supply spool (1) and the take-up spool (2), wherein the supply spool (1) is driven by a supply motor (10) and the take-up spool (2) is driven by a take-up motor (11), and wherein the printer comprises a spool drive controller (19) which is configured to energize the supply motor (10) and the take-up motor (11) so as to arrange that the tape (7) is unwound from the supply spool (1) and wound onto the take-up spool (2), characterized in that the spool drive controller (19) is embodied with field oriented control driving the supply motor (10) and the take-up motor (11) so as to continuously and uninterruptedly control motor torque of said motors.

2. Thermal transfer printer according to claim 1, characterized in that the supply spool (1) is provided with a supply encoder (20) and the take-up spool (2) is provided with a take-up encoder (21), which encoders (20, 21) provide positional information, and said encoders (20, 21) being connected to the spool drive controller (19) so as to arrange that the spool drive controller (19) controls the tape's tension, position and speed.

3. Thermal transfer printer according to claim 1 or 2, characterized in that the printhead (18) is driven by a motor for driving the printhead (18) down to produce a force by pressing the substrate (9) down onto a counter pressure platen (8), wherein the motor is energized with field oriented control.

Description

[0011] In the drawing:

[0012] the FIGURE shows an apparatus according to the invention.

[0013] The single FIGURE shows schematically and functionally some components of a thermal transfer printer according to the invention, notably a supply spool 1 with tape to be unwound and to be wound up onto a take-up spool 2. In transferring from the supply spool 1 to the take-up spool 2 the tape 7 passes a printhead 18 which when energized causes ink to be transferred from the tape 7 to a substrate 9. A platen 8 provides counter pressure to the substrate 9 during activation of the printhead 18. The functionality of the supply spool 1 and the take-up spool 2 can also be reversed.

[0014] The tape 7 is guided from the supply spool 1 to the take-up spool 2 along guides 3, 4, 5, 6.

[0015] Rotation of the supply spool 1 and the take-up spool 2 is caused by a supply motor 10 and a take-up motor 11 that drive the supply spool 1 and take-up spool 2 either directly or through a system of belts 14, 15 and toothed wheels 12, 13 and 16, 17 or gears.

[0016] The supply motor 10 and the take-up motor 11 are controlled by a spool drive controller 19 which takes account of the amount of tape 7 being present on the supply spool 1 and the take-up spool 2. Preferably for this purpose the supply spool 1 and the take-up spool 2 are provided with position encoders 20, 21 that provide the spool drive controller 19 with positional information. Said encoders 20, 21 are connected to the spool drive controller 19 so as to arrange that the spool drive controller 19 controls the tape's tension, position and speed, wherein the spool drive controller 19 is embodied with field oriented control so as to drive the supply motor 10 and the take-up motor 11 to continuously and uninterruptedly control the motor torque of said motors 10, 11.

[0017] According to another aspect of the invention the printhead 18 is driven by a motor (not shown) for driving the printhead 18 down to produce a force by pressing the substrate 9 down onto the counter pressure platen 8, wherein the motor for the printhead 18 is energized with field oriented control.

[0018] Although the invention has been discussed in the foregoing with reference to an exemplary embodiment of the apparatus of the invention, the invention is not restricted to this particular embodiment which can be varied in many ways without departing from the invention. The discussed exemplary embodiment shall therefore not be used to construe the appended claims strictly in accordance therewith. On the contrary the embodiment is merely intended to explain the wording of the appended claims without intent to limit the claims to this exemplary embodiment. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved using this exemplary embodiment.