JPH11342661A - Label printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a table structure for determining the ribbon diameter by determining the outside diameter of an ink ribbon from the count of steps being taken during rotation of a rotary encoder for detecting the rotational angle of a ribbon core and then regulating the driving voltage of a DC motor for rotating the ribbon core depending on the outside diameter thus determined. SOLUTION: A motor driver 5 connected through the bus line 2 of a CPU 1 is connected with a stepping motor 10 and a DC motor 11 for carrying a label sheet and an ink ribbon. An I/O 9 is connected with a rotary encoder 15 for detecting the rotational angle of a ribbon core and a counter 16 for counting the number of steps of the stepping motor 10. Ribbon diameter is detected by counting the number of steps required for driving the stepping motor 10 forward to turn the rotary encoder 15 by a specified angle. Driving voltage of the DC motor 11 for turning the ribbon core is regulated depending on the ribbon diameter thus detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a label printer which prints predetermined items on a label sheet using an ink ribbon.

[0002]

2. Description of the Related Art Conventionally, some label printers have a thermal head, and print predetermined items on a label by transferring ink of an ink ribbon to label paper. In such a label printer, the ink ribbon is transported together with the label paper.

[0003] The ink ribbon is supported in a state of being wound up from both ends by a ribbon core. When the ink ribbon moves in accordance with the movement of the label paper, the moved amount is wound up by the ribbon core. The ribbon core is driven by a torque given from a DC motor. The torque of the DC motor is controlled by switching the drive voltage.

Here, in order to obtain good printing accuracy,
The tension of the ink ribbon must be kept substantially constant. If the drive voltage of the DC motor is constant, the torque will be constant, so if the diameter of the ink ribbon wound around the ribbon core changes, the tension of the ink ribbon will change. Therefore, in some of such label printers, the tension of the ink ribbon is made substantially constant by controlling the torque by switching the drive voltage of the DC motor in accordance with the change in the diameter of the ink ribbon.

Conventionally, the ribbon diameter is detected by calculating the length of the ink ribbon corresponding to the predetermined angle of the ribbon core by multiplying the feed speed by the time required for the ribbon core to rotate by a predetermined angle, and calculating the length of the ink ribbon. Calculate the ribbon diameter from the length.

[0006] The feed speed varies depending on the printing speed, and the printing speed depends on the printing ratio and the like.

[0007] The rotation required time per predetermined angle of the ribbon core is determined by using a rotary encoder attached to the ribbon core. Conventionally, a period in which the optical sensor output signal in the slit plate of the rotary encoder has an H level and a period in which the optical sensor output signal has an L level next thereto constitute one cycle, and the time taken for the ribbon core to rotate for one cycle of the slit plate is defined as Then, the ribbon diameter is determined from the length of the ribbon corresponding to that time.

Since the ribbon diameter detection routine interrupts every unit time and refers to the output signal of the optical sensor, the time required for rotation for one cycle of the slit plate is obtained from the number of interruptions of the ribbon diameter detection routine. .

[0009]

As in the prior art, when the ribbon diameter is determined from the required rotation time of the ribbon core, a table for obtaining the ribbon diameter from the number of interruptions is required to cope with the feed speed that varies depending on the printing speed. Must be provided for each printing speed, which complicates the table structure.

[0010] Some label rolls used in label printers have an interval from a label sheet to the next label sheet shorter than a distance from a print head to an issuing port. In the case of such a label roll, when printing is performed up to the printed label paper and a new printing is started, the unprinted label paper passes through the thermal head and is located downstream in the paper transport direction. The label roll is back-fed to position the printed label paper in the proper position.

For this reason, if the ribbon diameter detection routine is interrupted even during the back feed, and the optical sensor output signal from the rotary encoder is taken in, the time required for one rotation of the slit plate is erroneously recognized. Conventionally, the detection of the ribbon diameter is performed only when the label roll is fed in the forward direction, and not when the label roll is returned.

When the ribbon diameter is large or the number of labels printed is small, the forward feed for one cycle of the slit plate may not be continuous. In such a case, the output signal of the optical sensor by the ribbon diameter detection routine cannot be obtained for one cycle of the slit plate, so that the ribbon diameter cannot be detected, so that the torque of the ribbon core cannot be properly controlled.

An object of the present invention is to simplify a table structure for obtaining a ribbon diameter.

It is another object of the present invention to provide a label printer capable of detecting a ribbon diameter even when label paper is not continuously fed in the forward direction.

[0015]

According to a first aspect of the present invention, there is provided a label printer, comprising: a thermal head for printing predetermined items on a label sheet by heating and transferring ink on an ink ribbon; A stepping motor for generating a driving force for transporting the ribbon, a ribbon core for winding the ink ribbon, a DC motor for generating a driving force for rotating the ribbon core, and a rotary encoder for detecting a rotation angle of the ribbon core;
A step number counter for counting the number of steps of the stepping motor, and a ribbon diameter for determining an outer diameter of the ink ribbon wound on the ribbon core from a count value of the step number counter while the rotary encoder rotates by a predetermined angle. Determining means; and voltage adjusting means for adjusting the drive voltage of the DC motor according to the ribbon diameter determined by the ribbon diameter determining means.

Accordingly, the ribbon diameter is detected by counting the number of steps required for the forward rotation drive of the stepping motor for rotating the rotary encoder by a predetermined angle. Since the lengths of the label paper and the ink ribbon sent in one step are constant irrespective of the printing speed, if the number of steps for a predetermined angle is known, the length of the ink ribbon for a predetermined angle is known, and the ribbon diameter is known.

According to a second aspect of the present invention, there is provided a label printer.
A thermal head for printing predetermined items on label paper by heating and transferring the ink of the ink ribbon,
A stepping motor for generating a driving force for transporting the label paper and the ink ribbon; a ribbon core for winding the ink ribbon; a DC motor for generating a driving force for rotating the ribbon core; and detecting a rotation angle of the ribbon core. A rotary encoder, a step number counter that counts the number of steps of the stepping motor by incrementing the number of steps when the stepping motor rotates forward and subtracting the number of steps when reversing the number of steps from the stepping motor; Ribbon diameter determining means for determining an outer diameter of the ink ribbon wound on the ribbon core from a value, and voltage adjusting means for adjusting a drive voltage of the DC motor according to the ribbon diameter determined by the ribbon diameter determining means. Is provided.

Therefore, the ribbon diameter is detected by counting the number of steps required for the normal rotation drive of the stepping motor for rotating the rotary encoder by a predetermined angle. Since the lengths of the label paper and the ink ribbon sent in one step are constant irrespective of the printing speed, if the number of steps for a predetermined angle is known, the length of the ink ribbon for a predetermined angle is known, and the ribbon diameter is known. According to the invention of this claim, the forward rotation of the stepping motor is not continuous only by rotating the rotary encoder by a predetermined angle, and even if reversal is mixed during the forward rotation of the predetermined angle, the number of steps for the reversal is reduced. It can be removed and the ribbon diameter can be detected.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a label printer according to the present invention will be described with reference to FIGS. FIG.
3 is a block diagram illustrating a control system of the label printer according to the present embodiment. As shown in FIG. 1, a CPU 1 that executes various arithmetic processes and controls each unit intensively has a ROM 3, a RAM 4, a motor driver 5, a head driver 6, a communication I / F 7, The display controller 8 and the I / O 9 are connected.

The ROM 3 is a medium for storing an operation program of the label printer, and the CPU 1 performs control according to the operation program. The RAM 4 temporarily stores various variable information, and a part of the area is used as a print buffer or an image memory, or as various counter areas.

The motor driver 5 has a stepping motor 10 and a DC motor 11 for transporting label paper and ink ribbon, the head driver 6 has a thermal head 12, the display controller 8 has a display 13, and
/ O9 has various sensors 14 and rotary encoder 1
5 are connected to each other.

Further, in this embodiment, a step number counter for counting the number of steps of the stepping motor 10 is provided. As a step number counter,
A predetermined area of the RAM 4 is used as a counter area.
Alternatively, a step number counter 16 having a hardware configuration shown by a virtual line in FIG. 1 may be connected to the I / O 9.

The rotary encoder 15 is attached to a ribbon core (not shown) for winding the ink ribbon, and includes a slit plate 17 (see FIG. 2) and an optical sensor 18 (see FIG. 2). The output signal of the optical sensor 18 is I /
It is transmitted to the CPU 1 via O9. A slit counter for counting the number of slits that have passed from the change in the state of the optical sensor output signal is provided. As the slit counter, a predetermined area of the RAM 4 is used as a counter area. Alternatively, a slit counter 19 having a hardware configuration shown by a virtual line in FIG. 1 may be connected to the I / O 9.

FIG. 2 is a schematic diagram showing an example of the locus of movement of the optical sensor 18 with respect to the slit plate 17. In the example shown in FIG. 2, the optical sensor 18 starts rotating from a start position S in a region A which is a slit. The optical sensor output signal is
At the boundary a between the area a and the area a, H changes to L or L changes to H. Similarly, the output signal of the optical sensor is switched at the boundary b between the region a and the region c and at the boundary c between the region c and the region d. Further, in the case of the example shown in FIG. 2, one cycle of the slit plate 17 is a section from the boundary a to the boundary c in which the area A outside the slit and the area C which is the slit are combined.

FIG. 3 is a flowchart of an initial operation performed when a state change appears in the optical sensor output signal for the first time after the start of rotation. First, the step number counter is reset (step S1), then the slit counter is reset (step S2), and the optical sensor output signal after the first state change after the start of rotation is saved as the "previous state". (Slit S3).

FIG. 4 is a flowchart of a print interruption routine. First, it is determined whether or not the stepping motor 10 is operating (step S11). If it is operating (Y in step S11), the process proceeds to step S12. Then, the rotation direction of the stepping motor 10 is determined (step S12), and if the rotation is forward (Y in step S12).
Proceeding to step S13, 1 is added to the step number count value (step S13). If it is inverted (N in step S12), the process proceeds to step S14, and 1 is subtracted from the step count value (step S14).

FIG. 5 is a flowchart of a ribbon diameter detection routine. The ribbon diameter detection routine interrupts every 5 msec. First, the output signal of the optical sensor 18 is checked (step S21), and the current state is compared with the saved "previous state" (step S22).

If the current state of the optical sensor output signal is the same as the "previous state" (N in step S22), since the boundary has not been passed yet, the process proceeds to step S32, and the current state is changed to the "previous state". (Step S32), and the interrupt is terminated.

If the current state is different from the previous state (Y in step S22), it indicates that the vehicle has passed the boundary. In this case, the rotation direction of the stepping motor 10 is determined (step S23). If the rotation is normal (Y in step S23), 1 is added to the slit count (step S24), and if the rotation is reversed (step S24). N in step S23: subtract 1 from the slit count (step S2)
5).

Subsequently, it is determined whether or not the total of the slit count has become 2 (step S26). If it has not become 2 (N in step S26), step S32 is executed.
Move to and change the current state of the optical sensor output signal to the "previous state".
(Step S32), and the interrupt is terminated.

If the number is 2 (step S26)
Y) Step count value is read (step S2)
7) The ribbon diameter is determined according to the read count value (step S28), and the voltage of the DC motor is adjusted according to the ribbon diameter (step S29).

Then, the step number counter is reset (step S30), the slit counter is reset (step S31), the current state of the optical sensor output signal is saved as the "previous state" (step S32), and an interrupt is generated. finish.

FIG. 6 shows the step count value X
It is a table | surface which shows the relationship between (refer FIG. 7) and a ribbon diameter. FIG.
Is stored in a predetermined non-volatile area of the RAM 4 in advance, and in step S28 of FIG. 5, the ribbon diameter is determined based on the data in accordance with the step number count value.

FIG. 7 shows the correspondence between the step number count value, the optical sensor output signal, the slit count, and the total when the optical sensor 18 moves with respect to the slit plate 17 as illustrated in FIG.

The optical sensor 18 is located at the start position S in the area A. At this time, the output signal of the optical sensor is H. When the slit plate 17 rotates forward by the forward rotation of the stepping motor 10, the optical sensor 18
7 in the direction.

When the optical sensor 18 passes the boundary a, it is detected that the optical sensor 18 has passed the boundary a by switching the output signal of the optical sensor from H to L. Since this is the first state change after the start of rotation, the step number counter is reset, the slit counter is reset by the initials shown in FIG. 3, and the optical sensor output signal L is saved as the “previous state”.

When the slit plate 17 further rotates forward, FIG.
The step count value is increased by the print interrupt routine shown in FIG. When the optical sensor 18 passes the boundary b, the optical sensor output signal changes from L to H. At this time, since the stepping motor 10 is rotating forward, 1 is added to the slit count. Here, since the total slit count is 1, the interruption ends after the optical sensor output signal H is saved as the “previous state”.

The slit plate 17 further rotates forward, during which time,
The step number count value further increases.

When the optical sensor 18 is located in the area c, the slit plate 17 is inverted and the optical sensor 18
Moves in the direction with respect to the slit plate 17. While the slit plate 17 is inverted, the step number count value decreases. The slit plate 17 is further inverted, and the optical sensor 18
Passes through the boundary b again. At this time, since the stepping motor 10 is being reversed, 1 is subtracted from the slit count. Here, since the total slit count becomes 0, the interruption ends after the optical sensor output signal H is saved as the “previous state”.

The slit plate 17 is further inverted, during which time,
The step number count value further decreases.

When the optical sensor 18 is located in the area A, the slit plate 17 rotates forward and the optical sensor 18
Moves in the direction with respect to the slit plate 17. While the slit plate 17 is rotating forward, the step count value increases. The slit plate 17 further rotates forward and the optical sensor 18
Passes the boundary b three times. At this time, since the stepping motor 10 is rotating forward, 1 is added to the slit count, and the total slit count becomes 1. Therefore, after the optical sensor output signal H is saved as the “previous state”, this interrupt ends.

The slit plate 17 further rotates forward, during which time,
The step number count value further increases. Optical sensor 18
Passes through the boundary c, then the stepping motor 1
Since 0 is in normal rotation, 1 is added to the slit count. Here, the total slit count is 2. Therefore, the ribbon diameter is determined according to the step number count value X at this time, and the DC motor voltage corresponding to the ribbon diameter is set. Then, after the step number counter is reset, the slit counter is reset, and the optical sensor output signal L is saved as the “previous state”, this interrupt ends.

In the present embodiment, the ribbon diameter is determined from the number of steps, and the printing speed is not affected by the correspondence between the number of steps and the ribbon diameter. There is no need to provide each table, and since there is only one type, the table structure can be simplified.

Further, in the present embodiment, the number of steps in which the stepping motor is normally rotated is integrated, and only the number of steps required for rotating the slit plate for one cycle is excluded, excluding the number of inverted steps. Since the ribbon diameter is determined from the number of steps and the ribbon diameter is determined from the number of steps, the forward rotation of the stepping motor is continuously performed for one cycle of the slit plate 17 unlike the case where the ribbon diameter is determined by the number of interruptions of the conventional ribbon diameter detection routine. The ribbon diameter can be determined even if the inversion is mixed by one rotation without performing the rotation.

Although the start position is provided in the slit in the example of FIG. 2 used in the description of the present embodiment, a similar result can be obtained even when the start position is outside the slit. be able to.

[0046]

According to the first aspect of the present invention, since the ribbon diameter is detected from the number of steps required to rotate the rotary encoder by a predetermined angle, the table for obtaining the ribbon diameter from the number of steps does not depend on the printing speed. Only one is required, and the table structure can be simplified.

According to the second aspect of the present invention, even if reversal is mixed during normal rotation of the rotary encoder by a predetermined angle,
The number of steps for normal rotation is counted excluding the number of steps for reversal, and the ribbon diameter is detected from the number of steps for normal rotation.Therefore, the gap between each label paper is narrow, and each time label paper is printed The ribbon diameter can be detected even if a label roll that needs to be sent or returned is used.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a control system of a label printer according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an example of a movement locus of an optical sensor with respect to a slit plate.

FIG. 3 is a flowchart showing initials performed when a state change appears for the first time after the start of rotation.

FIG. 4 is a flowchart illustrating a print interrupt routine.

FIG. 5 is a flowchart illustrating a ribbon diameter detection routine.

FIG. 6 is a table showing a relationship between a step number count value and a ribbon diameter.

FIG. 7 is a timing chart showing a correspondence relationship between a step number count value, an optical sensor output signal, a slit count, and a total thereof.

[Explanation of symbols]

 10 Stepping motor 11 DC motor 15 Rotary encoder 16 Step number counter

Claims (2)

[Claims] 1. A thermal head for printing predetermined items on label paper by heating and transferring ink on an ink ribbon, a stepping motor for generating a driving force for transporting the label paper and the ink ribbon, and the ink A ribbon core for winding a ribbon, a DC motor for generating a driving force for rotating the ribbon core, a rotary encoder for detecting a rotation angle of the ribbon core, a step number counter for counting the number of steps of the stepping motor, and the rotary encoder A ribbon diameter determining means for determining an outer diameter of the ink ribbon wound on the ribbon core from a count value of the step number counter while rotating by a predetermined angle, and a ribbon diameter determined by the ribbon diameter determining means. Adjusting the driving voltage of the DC motor Label printer comprising: a pressure regulating means. 2. A thermal head that prints predetermined items on label paper by heating and transferring ink on an ink ribbon, a stepping motor that generates a driving force for transporting the label paper and the ink ribbon, and the ink. A ribbon core for winding the ribbon; a DC motor for generating a driving force for rotating the ribbon core; a rotary encoder for detecting a rotation angle of the ribbon core; and the number of steps of the stepping motor added when the stepping motor rotates forward. A step number counter that counts by subtracting when reversing; and a ribbon diameter determination that determines an outer diameter of the ink ribbon wound on the ribbon core from a count value of the step number counter while the rotary encoder rotates by a predetermined angle. Means, said ribbon diameter determining means is determined Label printer comprising: a voltage regulating means, a to adjust the driving voltage of the DC motor in accordance with the ribbon diameter was.