JPH082078A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To provide a thermal transfer printer applying constant tension to a long ink ribbon showing a behavior extremely different in the ratio of a roll diameter. CONSTITUTION:The DC motor 9 connected to a feed roll is excited on an unwinding side when back tension is required and excited on a ribbon feed side when the tension of an ink ribbon 5 becomes lower than the back tension according to preset data by the detection of a sensor 18 detecting the diameter of the feed roll to apply proper tension to the ink ribbon 5 fed at constant speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer which applies a constant back tension to an ink ribbon.

[0002]

2. Description of the Related Art In a thermal transfer printer, an ink ribbon is sent between a thermal head and a sheet of paper, the ink of the same ink ribbon is melted by the thermal head, and the ink is transferred to the sheet of paper.

The ribbon feeding of this printer uses a feeding roller.
A structure is used in which an ink ribbon wound around a roll is connected to a winding roll through the tip of a thermal head. Then, the ink ribbon is wound at a constant speed synchronized with the paper feed speed by the rotational drive of the winding roll.

In such a printer, back tension is applied to the ink ribbon from the side of the supply roll so that the ink ribbon is tensioned so that wrinkles do not occur on the ink ribbon.

By the way, the back tension must be constant and proper so that the ink ribbon is not broken.

However, the outer diameters of the supply roll and the take-up roll change with the feeding of the ink ribbon.

Specifically, the beginning of winding the ink ribbon is
The supply roll has the maximum diameter, and the winding roll has the minimum diameter.
The same diameter changes as it is fed, and at the end of winding the ink ribbon, the supply roll has the smallest diameter and the winding roll has the largest diameter.

Therefore, in order to maintain a constant back tension, the ink ribbon tension is large at the beginning of the ink ribbon winding, and the ink ribbon tension is small toward the end of the ink ribbon winding. Will be needed.

Therefore, in the past, the DC roll was supplied to the supply roll.
A constant back tension is maintained by connecting the motor and exciting the DC motor in a direction opposite to the ribbon feeding direction according to the roll diameter.

[0010]

By the way, in the thermal transfer printer, the use of an ink ribbon having a longer overall length than ever has been promoted due to a longer operating time.

When such an ink ribbon is used, the outer diameter of the take-up roll is the same as that of a conventional roll in the state of starting winding.
It is much smaller than the roll diameter, and the outer diameter of the supply roll is, on the contrary, larger than the conventional roll diameter. The situation at the end of winding is the opposite.

Even when such an ink ribbon is used,
Back tension is required.

Therefore, it is conceivable to apply the above-mentioned back tension structure to this.

However, this is not enough.

That is, in the ink ribbon, the winding force in the winding roll overcomes the unwinding force generated in the DC motor of the supply roll to obtain the required tension. It is sent at a constant speed.

More specifically, the DC motor of the supply roll is rotated in the feeding direction of the ink ribbon while trying to rotate in the rewinding direction. The load generated at this time becomes the back tension of the ink ribbon.

However, in the ink ribbon having a long total length as described above, the ratio of roll diameters on the take-up side and the supply side is extremely different, so that the range of torque change becomes large, and as a result, the above-mentioned situation is reached. A technique of adding tension using reverse excitation cannot be applied.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an ink ribbon having a long overall length which exhibits behaviors in which the ratios of roll diameters are extremely different. Another object of the present invention is to provide a thermal transfer printer that can provide a constant tension.

[0019]

In order to solve the above problems, a thermal transfer printer according to a first aspect of the present invention comprises a take-up roll and a supply roll, and a ribbon feeding mechanism for feeding an ink ribbon. A forward and backward reversible motor for driving the supply roll in the feeding direction of the ink ribbon, in the opposite direction, and a detection means for detecting the size of the roll diameter, Depending on the setting means in which the torque value for generating a predetermined reference tension and the torque values of the positive and negative tensions that increase and decrease from that value are set according to the roll diameter, and the detection result of the detection means. And a control means for controlling the motor to the torque value set in the setting means.

In addition to the above-mentioned object, the thermal transfer printer according to the present invention also has a winding roll and a supply roll in order to reduce the load on the motor. A ribbon feeding mechanism for feeding the ink ribbon, a torque limiter for applying a back tension with a predetermined force in a direction opposite to the feeding direction of the ink ribbon, and a motor for driving the supply roll in the feeding direction of the ink ribbon. A detection means for detecting the size of the roll diameter, a setting means for setting a torque value that continuously increases and decreases in the torque region of the torque limiter according to the roll diameter, and the detection means. And a control means for controlling the motor so that the torque value set in the setting means is obtained from the detection result.

[0021]

According to the thermal transfer printer of claim 1,
With respect to the ink ribbon sent at a predetermined speed, from the beginning of winding the ink ribbon, the motor load obtained by the reverse rotation excitation of the motor driven by the torque value according to the roll diameter is the back tension. Given as.

The back tension due to the motor reverse rotation excitation is performed until the roller diameter does not require the back tension.

When the roller diameter becomes the same, the motor is demagnetized.

Then, after the roller diameter has passed, the back tension itself becomes excessive even when the motor is demagnetized.

At this time, the motor is excited in a positive rotation with a torque value corresponding to the roll diameter to assist ribbon feeding.

The adjustment of the tension on the negative side continues until the end of winding.

For an ink ribbon having a long overall length, this is controlled to an appropriate tension from the beginning of winding to the end of winding.

According to the thermal transfer printer of the second aspect, the torque generated by the torque limiter covers the area when a large back tension is required, such as the start of winding the ink ribbon.

This means that the ink ribbon is given a predetermined back tension only by the torque of the torque limiter.

When the torque range of the torque limiter is exceeded,
The back tension itself becomes excessive.

At this time, the motor is excited in the positive rotation with a torque value corresponding to the roll diameter to assist ribbon feeding.

The adjustment of the tension on the negative side continues until the end of winding.

As a result, as in the case of the first aspect, an appropriate tension is controlled from the beginning of winding to the end of winding for an ink ribbon having a long overall length.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the first embodiment shown in FIGS.

FIG. 1 shows a schematic structure of a transfer printer to which the present invention is applied, together with a state at the beginning of winding and a state at the end of winding.

In FIG. 1, reference numeral 1 denotes a sheet conveying path which is composed of a sheet guide 1a and extends to the left and right, and 2 denotes a sheet set on the sheet conveying path 1.

A platen roller 3 is provided on the lower side of the paper transport path 1 so that the paper 2 on the paper transport path 1 can be fed in the direction of the arrow.

A platen roller is provided on the upper side of the sheet conveying path 1.
Thermal head, for example, edge type, that works with La3
A round head 4 (recording head) is provided.

Further, the platen roller 3 and the thermal head 4
The ink ribbon 5 is interposed between the heating element (not shown) at the tip of the ink ribbon.

The ink ribbon 5 is wound around a feed roll 6 provided on the rear side of the thermal head 4 in the sheet conveying direction. As the ink ribbon 5, a ribbon having a long overall length is used.

The leading end of the ink ribbon 5 is a winding roll 7 provided on the front side in the sheet conveying direction with the thermal head 4 interposed therebetween.
Connected to. FIG. 1A shows a state in which the roll diameter is extremely different at the beginning of the ribbon winding, and FIG. 1B shows a state in which the roll diameter is extremely different at the end of the ribbon winding.

The winding roll 7 has a winding mechanism (not shown) using a motor, for example, a DC motor 8 as a driving source.
Is connected. With this winding mechanism, the ink ribbon 5 is made to run at a constant speed so that the unprinted ink ribbon 5 can be wound up.
Is composed.

The feed roll 6 is connected to a feed mechanism 10 using a motor, for example, a DC motor 9 capable of forward and reverse rotation as a drive source.

A constant back tension is generated on the ink ribbon 5 by the feeding mechanism 10.

The structure of the feeding mechanism 10 is shown in FIGS.

That is, 13 is a feed shaft whose one end is connected to the feed roll 6.

The feed shaft 13 includes a plurality of transmission gears 14
Via the transmission mechanism 15 of the gear train that meshes
It meshes with the pinion gear 16 on the output shaft of the motor 9, and the feed roll 6 is rotated in the normal direction (ribbon feed direction) or the reverse direction by the rotational force of the DC motor 9 in the forward and reverse directions. It is designed to rotate in the direction (direction opposite to the ribbon feeding direction).

Further, the pinion gear 16 is provided with a gear 17 in which a large number of slits 17a are provided at predetermined intervals in an arm wall portion which supports the tooth portion. Furthermore, this gear 17
Is provided with an optical transmission type sensor-18 (detection means) for detecting the presence or absence of the slit 17a.

The DC motor 9 and the sensor 18 are
A DC motor 8 on the take-up side and a motor (not shown) for driving the platen roller 3 are connected to a controller 19 (for example, constituted by a micro computer, corresponding to control means). It

The memory 20 (setting means) connected to the controller 19 has a DC motor as shown in FIG.
Map A showing the relationship between the rotation speed and the torque of the motor 9 at a predetermined rated voltage, and the map showing the relationship between the roll rotation speed (feed roll) and the roll diameter (feed roll). B, and further, a torque setting map C defined using the map B is stored.

The torque setting map C is based on, for example, the value X when the roll diameter does not require back tension at a certain ribbon speed and gear ratio, and this value X is used.
It is a diagram in which the required tension values on the positive and negative sides that increase and decrease according to the roll diameter are plotted.

The controller 19 has a function of detecting the roll diameter of the feed roll 6 according to the detection signal of the sensor 18, and a torque setting point corresponding to the roll diameter from the torque setting map C. A function to determine, a characteristic line intersecting the same set point, for example, a function to obtain maps B _{1 to} B ₃ , a map B _{1 to be} obtained
The function of calculating the torque value of the back tension required from B ₃ to B ₃ and the function of driving the DC motor 9 in the ribbon feeding direction or in the direction opposite to the ribbon feeding direction are set to the same torque value. ing.

Due to the function of the controller 19,
An appropriate tension is applied to the ink ribbon 5 from the beginning to the end of winding.

Next, the operation of the thermal transfer printer thus constructed will be described.

When the print start signal is input, the control is
The la 19 operates the thermal head 4 to transfer the sheet 2 fed at a constant speed through the ink ribbon 5 fed by the ribbon feeding mechanism 11.

At this time, the controller 19 gives the back tension F to the ink ribbon 5 through the feeding mechanism 10.

The control of the back tension F is shown in the flowchart of FIG.

To explain this control, the controller 19
Is sent from the detection signal input from the sensor-18.
The rotation speed of rule 9 is detected, and map B is used to determine the current roll.
I'm seeking the diameter.

The controller 19 also detects the same detected roller.
It is compared with the roll diameter and the roll diameter Rc (shown in FIG. 4) corresponding to the X value that does not require the energization of the DC motor 9.

Here, the feed roll 6 is in a state where the outer diameter at the beginning of winding is the largest.

However, the controller 19 determines that the detected roll diameter is larger than the roll diameter Rc, and drives the feed roll 6 in the direction opposite to the feed direction.

That is, the controller 9 defines a torque set point a corresponding to the same roll diameter from the torque set map C, and a map B ₁ (predetermined rated voltage E ₀₎ intersecting the set point a.
The characteristic line at that time is shifted in parallel until it intersects with the set point a).

Then, the controller 9 obtains a linear voltage Ea on the map B ₁ passing through the same set point a, and obtains a torque value required to generate the back tension F.

That is, the same voltage Ea is E ₀ = Ta /
It can be obtained by T ₀ (or E ₀ = Na / N ₀ ).

Then, the controller 9 excites the DC motor 9 in the opposite direction so as to obtain this voltage value.

The motor load obtained by the DC motor 9 is applied to the ink ribbon 5 as back tension. That is, for the load of the DC motor 9, the radius of the first winding start roll diameter (winding diameter) is Ra, the back tension force is F, and the required torque is "F × Ra". Assuming that the rotation speed at Ra is Nra, the gear ratio of the gear train is S, and the gear efficiency is η, (F × Ra) / S · η
It is represented by.

The back tension applied by the reverse rotation excitation of the DC motor 9 has a roller diameter Rc which does not require back tension.

Then, when the roller diameter becomes Rc, the DC motor
The parameter 9 is demagnetized, that is, the voltage value becomes "0V".

Further, as the use of the ink ribbon 5 progresses,
The detected roll diameter of the feed roll 6 exceeds the roll diameter Rc.

The area beyond this is an area where the tension generated by winding is excessive.

At this time, contrary to the above, the controller 19 causes the DC motor 8 to rotate in the forward direction according to the detection roll diameter, that is, the ribbon feeding direction (ink ribbon) according to the roll diameter. 5 is excited in the direction from the feed roll 6 toward the winding roll 7).

This assists in advancing the ink ribbon 5.

The control for assisting the feeding of the ink ribbon 5 continues until the end of winding.

As a result of such control, as shown in FIG. 6, the winding start Ra is applied to an ink ribbon having a long total length, which has conventionally been considered to be extremely different in the ratio of roll diameters. The tension can be properly controlled from to the winding end Rb.

Moreover, the diameter of the feed roll 6 can be increased.

By incorporating a means for changing the drive voltage of the DC motor 8 of the take-up roll 7 according to the roll diameter of the take-up roll 7 in this embodiment, the ink can be more accurately printed. The tension of the ribbon 5 is maintained.

7 to 9 show a second embodiment of the present invention.

In the present embodiment, the load on the DC motor 9 (because the motor is rotated against the force to rotate in the rewinding direction, causing counter electromotive force). The torque limiter 30 is also used to reduce the torque.

That is, as shown in FIG. 7, a torque limiter 30 which applies a constant back tension to the ribbon winding shaft 13 in the direction opposite to the feeding direction of the ink ribbon 5.
Is provided. Reference numeral 31 represents a frame on which the torque limiter 30 is installed.

A torque limiter 30 as shown in FIG. 8 is provided in the memory 20 of the controller 19 (the vicinity of the feed mechanism 10 is the same as that of the first embodiment, so the drawing is also used).
The torque value that continuously increases and decreases in the torque region, including the torque region obtained in step 1, is stored according to the roll diameter.

The controller 19 includes a torque limiter 3
When the torque range cannot be handled with 0, the detected low
The function of reading the torque value according to the radial diameter, the voltage value of the DC motor 9 corresponding to the torque value is read from the read torque value using the map shown in FIG. 9 as in the first embodiment. The required function is set.

When such a structure is applied, the torque generated by the torque limiter 30 covers a region such as the beginning of winding of the ink ribbon 5, which requires a large back tension.

That is, a predetermined back tension is applied to the ink ribbon 5 only by the torque of the torque limiter 30.

If the torque range of the torque limiter 30 is exceeded, the back tension itself becomes excessive.

Then, when the roller diameter corresponding to the torque region has elapsed, the controller 19 rolls from the map shown in FIG. 8 as in the flow chart shown in FIG.
A torque value corresponding to the diameter of the DC motor 9 is obtained, and the voltage value of the DC motor 9 corresponding to the torque value is obtained from the map shown in FIG.

Then, similarly to the first embodiment, the DC motor 9 is excited in the positive direction by this voltage value, that is, rotated in the ribbon feeding direction to assist the ribbon feeding.

Even in this way, similarly to the first embodiment,
An appropriate tension can be controlled from the beginning to the end of winding of the feed roller 6.

Moreover, with this control, the back tension portion is taken over by the torque limiter 30, and the DC motor 9-
Since the control is performed only in the normal rotation in the normal direction (no generation of counter electromotive force), the load on the DC motor 9 is significantly reduced.

Although the DC motor is used as the motor because the torque control is easy in the above embodiment, the present invention is not limited to this, and other motors may be used.

[0090]

As described above, according to the first and second aspects of the present invention, a constant tension is applied to an ink ribbon having a long overall length that exhibits behaviors in which the ratios of roll diameters are extremely different. Can be given.

Moreover, according to the second aspect of the invention, the control for exciting the motor in the direction opposite to the ribbon feeding is reduced, and the load on the motor can be remarkably reduced.

[Brief description of drawings]

FIG. 1A is a diagram showing a schematic configuration of a thermal transfer printer according to a first embodiment of the present invention together with a winding start state of a feed roll. (B) is a figure which similarly shows the winding end state of a feed roll.

FIG. 2 is a plan view showing the configuration of a feeding mechanism.

FIG. 3 is a front view of the same.

FIG. 4 is a diagram for determining the operation in the reverse rotation direction and the operation in the normal rotation direction of the DC motor.

FIG. 5 is a flowchart for explaining control of the DC motor.

FIG. 6 is a diagram for explaining that proper tension is applied to the link ribbon from the start of winding to the end of winding by the control of the same DC motor.

FIG. 7 is a plan view showing a feeding mechanism with a torque limiter, which is a main part of a second embodiment of the present invention.

FIG. 8 is a diagram for determining the operation of the DC motor.

FIG. 9 is a diagram for explaining control of the DC motor.

FIG. 10 is a flow chart for explaining control of the DC motor.
Chart.

[Explanation of Codes] 1 ... Paper transport path 2 ... Paper 3 ...
Platen roller 4 ... Thermal head (recording head) 5 ...
Ink ribbon 6 ... Feed roll (Supply roll) 7 ...
Take-up roll 9 ... DC motor 10 ... Feeding mechanism 11 ...
Ribbon mechanism 18 ... Optical transmission type sensor (detection means) 19 ... Controller (control means) 20
... Memory (setting means) 30 ... Torque limiter

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[Procedure amendment]

[Submission date] September 5, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008] Therefore, in order to maintain a constant back tension, winding start of the ink ribbon is given to Lee Nkuribon
Larger obtain torque, it is necessary to reduce the torque applied to the ink ribbon toward the winding end of the ink ribbon.

Claims (2)

[Claims] 1. A ribbon feed mechanism having a take-up roll and a supply roll, for feeding an ink ribbon, and driving the feed roll in the feeding direction of the ink ribbon, and in the opposite direction. A motor capable of positive / reverse rotation for detecting, a detecting means for detecting the size of the roll diameter, a torque value for generating a predetermined reference tension, and a positive / negative side for increasing / decreasing from the torque value. Setting means for setting the torque value of the tension according to the roll diameter, and control means for controlling the motor so that the torque value is set by the setting means according to the detection result of the detecting means. A thermal transfer printer comprising: 2. A ribbon feed mechanism having a take-up roll and a supply roll for feeding an ink ribbon, and a back tension having a predetermined force in a direction opposite to the feeding direction of the ink ribbon. A torque limiter, a motor for driving the supply roll in the feed direction of the ink ribbon, a detection means for detecting the size of the roll diameter, and a torque region of the torque limiter. Setting means for setting the torque value that increases and decreases according to the roll diameter, and control means for controlling the motor to the torque value set in the setting means according to the detection result of the detection means. And a thermal transfer printer.