JPH01275178A - Thermal transfer recording method - Google Patents

Abstract

PURPOSE:To obtain recording of good image quality, by a method wherein a peeling angle of a thermal transfer medium to a medium to be recorded is specified and besides, forward tension of the thermal transfer medium is made to be within a specified range to perform recording. CONSTITUTION:When alpha( deg.) for a peeling angle of a thermal transfer medium to a medium to be recorded, W(cm) for a width of the thermal transfer medium, and Y(cm) for a maximum recording width are adopted, the peeling angle is established to be less than 40 deg.. Then, heating ink and non heating ink are slowly ruptured, and an extension state of the heating ink becomes constant and therefore, an image edge becomes sharp. Further, when forward tension of the thermal transfer medium Tf is made larger than (20Y)/(1-Cosalpha), peeling of the thermal transfer medium to the medium to be recorded is stabilized, the heating ink is ruptured from the non heating ink before cohesion recovers, and an image edge appears clearly. Further, when forward tension Tf is made less than 350W, rupture of the thermal transfer medium itself is prevented, and shift of the thermal transfer medium to the medium to be recorded is prevented. Then, deterioration of the image can be removed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a thermal transfer recording method that enables recording with clear image edges.

<Prior Art> Today, various recording methods have been developed as input information output devices, and a typical example is a thermal transfer recording method.

In this recording method, an ink ribbon coated with thermal transfer ink mainly composed of wax and recording paper are pressed against a platen by a recording head, and in this state, the recording head is selectively heated to print the ink sheet. The applied thermal transfer ink is melted in the form of an image pattern and transferred and recorded onto recording paper. Because it is small, lightweight, and low-noise, it is widely used as an output device for word processors, electronic typewriters, etc. (It is used.

<Problems to be Solved by the Invention> In the thermal transfer recording method described above, the image quality varies depending on the smoothness of the recording paper, and especially when recording paper with low smoothness such as rough paper is used, the transferred image It is difficult for the edges to become sharp, and when using a thermal transfer ink containing wax as a main component, the image density may become thinner.

Therefore, attempts have been made to increase the image density by using thermal transfer inks that are mainly composed of resins with relatively high melt viscosity, but because the ink spreads easily, the sharpness of the image edges is insufficient. It was difficult to obtain sufficient image quality.

The present invention solves the above-mentioned conventional problems and is a thermal transfer recording method capable of recording images with good image quality by setting the peeling angle of the thermal transfer medium with respect to the recording medium and the forward tension of the thermal transfer medium to appropriate values. This is what we intended to provide.

<Means for Solving the Problems> The means according to the embodiments described below for solving the above problems is a thermal transfer recording method in which a recording head selectively heats a thermal transfer medium to perform transfer recording on a recording medium. Then, we used a recording disk in which heating elements that generate heat according to image signals are arranged near the edge of the substrate, and the peeling angle of the thermal transfer medium with respect to the recording medium was set to α (°), and the width of the thermal transfer medium was set to W (
cm), and the maximum recording width is Y (■), the peeling angle α is set to α<40°, and the forward tension Tt of the thermal transfer medium is set to (20Y)/(1-Co
It is characterized in that recording is performed with sα)<Tr<350W.

Another feature is that a thermal transfer ink containing resin as a main component is used as the thermal transfer medium.

According to the above means, the heated ink and the non-heated ink are broken gently to make the peeling angle α smaller than 40°, and the extended state of the heated ink is kept constant, so that the image edges are sharpened. Become.

Also, the forward tension Tt of the thermal transfer medium is (20Y
)/(1-Cosα), the separation of the thermal transfer medium from the recording medium is stabilized, the heated ink breaks from the non-heated ink before the cohesive force is recovered, and image edges appear clearly.

Further, by setting the forward tension T to be smaller than 350 W, the thermal transfer medium itself is prevented from breaking, and the thermal transfer medium is also prevented from slipping relative to the recording medium, thereby eliminating image deterioration.

<Embodiment> Next, an embodiment in which the above means is applied to a serial type thermal transfer recording system will be described with reference to the drawings.

[First example]

FIG. 1 is a perspective explanatory view of a thermal transfer recording apparatus according to a first embodiment for carrying out the above-described thermal transfer recording method, FIG. 2 is a cross-sectional explanatory view of a thermal transfer medium, and FIG. 3 (^).

(B) is a cross-sectional explanatory diagram of the recording section during non-recording and during recording.

First, the general structure of the entire apparatus will be described. An ink ribbon 2 serving as a thermal transfer medium is housed in a cassette 1, and the cassette 1 is removably mounted on a carriage 3. Further, this carriage 3 is configured to be able to reciprocate along a carriage shaft 5 by a drive mechanism 4. When the carriage 3 moves in the six directions of arrows, the ink ribbon 2
The ink ribbon 2 is fed out by the conveyance roller pair 6 forming the conveyance means, and the recording head 7 heats the ink ribbon 2, and the recording medium (such as a paper feed or a plastic sheet, etc.) whose back side is supported by the platen 8 is fed out. The heated ink is transferred onto a recording paper 9 (hereinafter referred to as "recording paper 1").Furthermore, the recording paper 9 is configured to be intermittently conveyed line by line by a conveying means (not shown).

Next, the configuration of each part will be explained in detail. First, the cassette 1 is composed of a lower case 1a and an upper cover 1b. Inside the lower case la, an ink ribbon 2 serving as a thermal transfer medium is attached to the supply reel of the cassette 1. It is wound around a take-up reel 1d, guided from the supply reel IC so as to be exposed through a cutout (not shown) in the lower case 1a, and then wound around a take-up reel 1d.

The ink ribbon 2 is a layered ink coated with a thermally transferable (heat-transferable, heat-softening, heat-sublimating, etc.) ink on a support, preferably an ink containing a resin, particularly preferably an ionomer resin. An ink containing the following is used.

Incidentally, ionomer resin refers to a hydrocarbon main chain with side chains of carboxyl groups that are partially or completely neutralized with metal ions or quaternary ammonium ions. Among ionomer resins, α-olefins such as ethylene and propylene, α,
A copolymer of β-unsaturated carboxylic acid neutralized with metal ions is used. The content of the ionomer resin in the thermal transfer ink component is preferably 5 to 70%.

The ink ribbon 2 used in this example has a width W=81,
As shown in FIG. 2, an intermediate layer 2b, a first transfer layer 2C, and a second transfer layer 2d are laminated in this order on a support 2a to form a thermally transferable ink layer. Specifically, the applicant filed the patent application No. 146380 (June 1, 1986).
2), a polyester film with a thickness of 6 mm is used as the support 2a, and the intermediate i2a,
The first transfer layer 2C1 and the second transfer layer 2d are each formed using the following components.

A belt 4C is connected to the carriage 3, which is passed between the boots 4a and 4b, and when the carriage motor 4d connected to the pulley 4a is driven, the carriage 3 is guided by the carriage shaft 5 and moves back and forth. It is composed of

When the carriage 3 moves in the direction of arrow A in FIG. By sliding in a pressed state, the ink ribbon 2 is sequentially fed out from the supply reel 1c.

Further, at a predetermined position of the carriage 3, a take-up motor 3a provided in the carriage 3 and a take-up shaft 3C connected via a friction clutch 3b are provided, and during recording (
When the carriage 3 moves in the direction of arrow A), it is configured to rotate in the direction of arrow C in synchronization with the movement of the carriage 3. The friction clutch 3b has a structure in which it stops transmitting the rotational force of the motor 3a to the take-up shaft 3c when a torque exceeding a certain level is applied, and engages the take-up rule 1d of the cassette l with the take-up shaft 3C. By driving the motor 3a, the ink ribbon 2 is transferred to the supply reel IC.
The amount fed out from the winding wheel 1d is wound up.

Further, a notch 3d is formed on the front surface of the carriage 3 at a position corresponding to the notch of the lower case la, and the notch 3d
A recording hand door is installed in the section so that it can be moved (in the direction of the arrow).

The recording head 7 includes a glaze layer (not shown) provided on a head substrate 7a, and a plurality of heating elements 7b arranged in a line in the glaze layer to generate heat when energized according to an image signal. Further, the heating element array is arranged near the downstream edge of the head substrate 7a in the direction in which the ink ribbon is fed out (so-called edge head). This is to make the ink peel off from the recording paper 9 and to improve ink drainage.

The distance ΔX from the end of the heating element 7b to the end of the head substrate 7a is preferably set to about 250 u or less, more preferably 150 u or less.

In this example, the thickness of the glaze layer for the door was 44 μm, and the dot density of the heating element array was 240 dots/1.
A nch with a length of 4.65 seconds and a distance ΔX from the substrate edge to the heat generating element array of 122 pl is used. Further, the length over which the recording head 7 presses against the platen 8 is 6 mm.

The recording head 7 is configured to move down during recording, press the ink ribbon 2 and the recording paper 9 into contact with each other by a pressing means IO, and press the platen 8 at a set pressure.

The platen 8 pressed by the recording head 7 is formed into a flat plate shape, and in this embodiment, it is made of hard rubber with a hardness of 73 degrees and is formed into a flat plate shape with a width of 5 mm, which is attached to a platen holder 8a. .

Next, the configuration of the pressing means 10 is such that, as shown in FIGS.
The head arm 10 is rotatably pivoted by the head arm 10.
The recording head 7 is supported at one end 10a+ of the hand arm loa, and the other end 10az of the hand arm loa and the pressing arm 10
A tension spring 10d is attached between c.

Further, one end of the pressing arm 10c is rotatably attached to the shaft 10b, and the other end is pressed against the outer periphery of the cam 10e by a tension spring 10f.

Therefore, when the cam 10e is rotated, the recording head door moves head down and head up. When the head is lowered, the spring 10d is pulled, and the recording head 7 presses the platen 8 with a predetermined pressure. The head pressure at this time is 800gf/cm or more and 3500gf/c+w
It is preferable to set it within the following range.
More preferably 1100 gf/cm or more and 2500 gf/cm
cm or less, more preferably 1600 gf/cm or more25
Set to 00 gf/cm or less.

Further, the ink ribbon 2 is configured so that the tension (hereinafter referred to as r-forward tension j) Tf on the downstream side in the transport direction of the ink ribbon 2 relative to the recording head 7, that is, on the winding side, can be changed by the tension means 11.

The structure of this tensioning means 11 is as follows:
la is rotatably attached to a shaft 11b, a moving roller llc is provided at one end thereof, and a tension spring lid is attached to the other end. Furthermore, the ink ribbon 2 is guided by guide rollers 12 provided in the lower case 1a.
a-12d and the moving roller Ilc of the tensicon arm Ila, and passes through a pair of conveying rollers 6 to reach the winding wheel 1d.

Therefore, the ink ribbon 2 is pulled upward in FIGS. 3(A) and 3(B) by the tensile force of the spring lid, thereby imparting forward tension Tf.

Furthermore, a magnet 11a is attached to the tensicon arm lla.
is attached, and a Hall element 11f is attached to the lower case 1a near the magnet lie. As a result, the magnet lie and the Hall element 11 f
The distance between the two tension arms Ila, that is, the inclination of the tension arm Ila, is detected, and the rotational speed of the transport roller pair 6 is controlled during printing to keep the position of the tension arm Ila constant, thereby applying a constant forward tension T to the ink ribbon 2. The structure is such that there is no delay in peeling off the ink ribbon 2 from the recording paper 9.

The forward tension TtO value is the spring lid
Although it can be freely set depending on the value of the forward tension T, in this embodiment, the forward tension T is in the range of about 35gf to 300gr, more specifically, the forward tension T is in the range of about 35gf to 300gr. , 11 The separation angle is α (degrees), and the width of the ink ribbon 2 is W
(c+a), when the maximum recording width is Y(effi), the forward tension Tr (gf) is (20
Y )/(1-Cos α) < T r < 35
Set it to be in the 0W range.

Further, the peeling angle α can be freely set by changing the position of the guide roller 12b, but in this embodiment, the peeling angle α is set in a range of 13° and α<40°.

Next, a recording method using the thermal transfer recording apparatus having the above configuration will be described.

Head down the recording head door and apply the platen 8 through the ink ribbon 2 and recording paper 9 to 800 gf/cm to 350 gf/cm.
Press with a head pressure of 0gf/(m, and move the carriage 3 to the third
The ink ribbon 2 is caused to travel in the direction of arrow A in FIG. 2B, and the ink ribbon 2 is sequentially fed out in the direction of arrow B to perform recording. At this time, the thermal transfer ink is melted and adhered to the recording paper 9 by the heat generated by the heating element 7b in response to the image signal. This molten ink has a high viscosity because its main component is resin, but the head pressure is 800 gf/cm to 3500 gf/cm.
Because of the high temperature, the fibers of the recording paper 9 are elastically deformed, and the high viscosity molten ink is fitted along the fibers, resulting in adhesion over a wide contact area.

Therefore, when the ink ribbon 2 is peeled off from the recording paper 9,
When the melted ink and the non-melted ink break, the length of the melted ink (extends like starch syrup) becomes smaller.

Further, since the angle at which the ink ribbon 2 is peeled off from the recording paper 9 is as small as 40 degrees or less, the molten ink and the non-melted ink break gently. As a result, the extension state of the molten ink becomes constant, and the sharpness of the image edges becomes good.

Generally, if the peeling angle α is made small, the edges of the molten ink cannot be reliably peeled off, and the peeling position is not constant. In particular, if the peeling position of ink mainly composed of resin is delayed, the cohesive force of the molten ink will recover and the ink that adhered to the recording paper 9 at the time of peeling will be peeled off from the recording paper 9 together with the non-melted ink, resulting in image edge loss. will occur.

Therefore, in order to prevent the image edge chipping, it is not sufficient to simply apply forward tension to the extent that the ink ribbon 2 can be peeled off from the recording paper 9, but it is necessary to stabilize the peeling state.

In this regard, in this embodiment, the forward tension Tr is 20
Since it is larger than Y/(1-Co5α), the ink ribbon 2 and the recording paper 9 are separated from each other before the molten ink recovers its cohesive force, so that the above-mentioned disadvantage does not occur.

However, if the forward tension T is excessively increased, not only the ink ribbon 2 itself may break, but also the image tends to deteriorate. The deterioration of the image is thought to be due to the ink ribbon 2 slipping against the recording paper 9 when the forward tension T is made too large. That is, the forward tension Tr is adjusted to prevent slippage between the ink ribbon 2 and the recording paper 9.
In contrast, it is necessary to adjust the tension (hereinafter referred to as r-pack tension) T on the upstream side of the ink ribbon 2 in the transport direction from the recording head 7 to an optimal value, but when the forward tension Tf is increased, If the back tension Tb is also increased accordingly, the tension T,
The value of T is much thicker than the frictional force between the ink surface of the ink ribbon 2 and the recording paper 9, and the ink ribbon 2
This is thought to be because the relative speed between the recording paper 9 and the recording paper 9 is not constant, resulting in an unstable state. Furthermore, in the recording section, there are static frictional forces between the ink surface of the ink ribbon 2 and the recording paper 9, and dynamic frictional forces between the support 2a of the ink ribbon 2 and the recording head 7, but these are affected by environmental temperature and humidity. , or change depending on the type of recording paper 9, recording pattern, etc., and it is difficult to completely control these.

In this regard, the forward tension T is used in this embodiment.

Since the power is set smaller than 350 W, problems such as breakage of the ink ribbon 2 and deterioration of the image do not occur.

Next, the results of an experiment in which thermal transfer recording was performed using the above-mentioned thermal transfer recording apparatus while changing the forward tension T of the ink ribbon 2 and the peeling angle α will be shown.

(1) Regarding the minimum forward tension, bond paper (Beck smoothness 2.5 seconds) and thermal transfer paper (Beck smoothness 80 seconds) were used as the recording paper 9, and the head pressure was 1167 g/c.
Recording was performed with the setting at m (700 gf).

FIG. 4 shows the minimum forward tension T and value required to prevent image edge loss. In this case, the recording pattern has a length of 4.65+n and a width of 210μ.
It was made into a continuous line of m. Image chipping was most likely to occur when such vertical lines with the maximum recording width W were recorded.

Also, for recording paper 9, the image chipping appeared more clearly on thermal transfer paper than on bond paper, but the required forward tension T
There was almost no difference in the values.

In the range where the forward tension Tt was larger than the solid line shown in the graph of FIG. 4, no chipping occurred in the image, but in the range smaller than the solid line, chipping was observed in the image.

Also, the length of the vertical line of the recording pattern is approximately 1/2, 2.3.
In the case of 3ts, the minimum forward tension T required to prevent image chipping was approximately 1/2 of that in the case of the maximum recording width W.

Furthermore, the length of the vertical line is 4.561, which is the maximum recording width.
1, the forward tension Tf necessary for the apparent separation at the edge portion of the recording head 7 was about 70% of the value of the solid line shown in the graph of FIG.

Here, the solid line graph in Figure 4 is the maximum recording width (0,465
01) It can be seen that the relationship between Y and peeling angle α is in extremely good agreement with the graph Tt = 20Y/(1-Cosα) shown by the - dotted chain line. Note that if the forward tension Tt exceeds 300 gf, the ink ribbon 2 will often break, making measurement difficult. This is a graph showing a subjective evaluation of the sharpness of the image edge portion by changing the peeling angle α.

In this experiment, the forward tension Tt was set to 280 gf, and the back tension T was changed to 200 gf or less for recording. The best image was obtained when the bank tension T was set to 150 gr compared to the forward tension T.

When the bond paper described above was used as the recording paper 9, as shown in the graph, when the peeling angle α exceeded 40°, the sharpness of the image edges deteriorated significantly.

In addition, when the above-mentioned thermal transfer paper is used as the recording paper 9,
There was no difference in the sharpness of the image edges at any peeling angle α, but when the peeling angle α exceeded 506, the sharpness tended to be slightly inferior.

(3) Maximum forward tension Figure 6 is a graph showing a subjective evaluation of images recorded on the bond paper and thermal transfer paper with the peel angle α constant at 30° and the forward tension T varied during recording. be.

Note that the back tension Tb was set to a value that would provide the best image quality when changing the forward tension.

First, when an ink ribbon 2 with a width of 811 mm was used, when the forward tension T exceeded 300 gf, the details of the image became blurred, the image quality deteriorated, and the variation in image quality also increased.

Further, when the pressure exceeded 300 gf, the ink ribbon 2 often broke.

Next, when recording was performed in the same manner using an ink ribbon 2 with a width of 6.3511, the forward tension Tt was 250.
When gf was exceeded, the image deteriorated and the ink ribbon 2 often broke.

From the above results, it was preferable that the forward tension Tr be smaller than 350 W with respect to the ink ribbon width W (css).

(4) Comprehensive evaluation Summarizing the results of experiments (1) to (3) mentioned above, the seventh
The result will be as shown in the figure.

The hatched area in FIG. 7 is the area where a good image can be obtained, and it can be seen that a good image can be obtained by setting the peeling angle α and the forward tension T in the ranges described above.

Note that the forward tension T is narrower than the above range, and (30Y)/(1-Cosα)<Tr<300
When set within the range of W, there is a margin against drive vibrations of the device, etc., and high-quality images can be stably obtained.

In this embodiment, as described above, by setting the peeling angle and forward tension within a certain range for recording, it is possible to obtain a good transferred image even on recording paper with low smoothness.

In the above example, the head pressure was set to 1167 gf/cya.
(700 gf), but similar results were obtained even if the hend pressure was set higher, for example, 16008 f/cm.

Conversely, the head pressure may be lowered, for example, 583 gf/cm.
(350 gf), the image quality as a whole is inferior, but relatively speaking, the hatched area shown in Fig. 7 is a better image than the other areas. Then, a preferable image was obtained in the hunting area shown in FIG.

Further, it is preferable to use an ink whose main component is resin as the thermal transfer ink, but the resin component of this ink is not limited to those mentioned above, and may also include, for example, acrylic resin, low molecular weight polyester resin, Urethane resins, styrene acrylic resins, polyamide resins, etc. can also be suitably used.

<Effects of the Invention> As described above, the present invention enables recording by setting the peeling angle and forward tension of the thermal transfer medium relative to the recording medium within a certain range, thereby producing not only a recording medium with high smoothness of the recorded image but also a recording medium with a high smoothness. , it is possible to transfer and record an image with clear image edges even on a recording medium with low smoothness.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a thermal transfer recording device according to an embodiment of the present invention, FIG. 2 is an explanatory view of the structure of an ink ribbon, and FIG.
A) and (B) are cross-sectional explanatory diagrams of the main parts of the recording section, FIG. 4 is a graph showing the relationship between the minimum forward tension and the peeling angle, FIG. 5 is a graph showing the relationship between the sharpness of image edges and the peeling angle, and FIG. FIG. 6 is a graph showing the forward tension for obtaining a good image, and FIG. 7 is a graph showing the overall evaluation of the transferred image. 1 is the cassette, 1a is the lower case, lb is the upper cover, 1c
is a supply reel, 1d is a take-up reel, 2 is an ink ribbon,
3 is a carriage, 3a is a winding motor, 3b is a friction clutch, 3c is a winding shaft, 4 is a drive mechanism, 4a, 4
b is a pulley, 4c is a belt, 4d is a carriage motor, 5 is a carriage shaft, 6 is a pair of transport rollers, 7 is a recording head, 7a is a substrate, 7b is a heating element, 8 is a platen, 8a
1 is a platen holder, 9 is a recording sheet, 10 is a pressing means, 10a is a helad arm, 10b is a shaft, 10c is a pressing arm, 10d is a tension spring, 10e is a cam, 1
0f is a tension spring, 11 is a tension means, l
la is a tension arm, Ilb is a shaft, llc is a moving roller, lld is a tension spring, lie is a magnet, llf is a Hall element, and 12a to 12d are guide rollers.

Claims (3)

[Claims] (1) A thermal transfer recording method in which a recording head selectively heats a thermal transfer medium to perform transfer recording on a recording medium, and is a recording method in which heating elements that generate heat according to image signals are arranged near the edge of a substrate. The separation angle of the thermal transfer medium from the recording medium is α (°), and the width of the thermal transfer medium is W.
(cm), and the maximum recording width is Y (cm), the peeling angle α is set to α<40°, and the forward tension T_f of the thermal transfer medium is set to (20Y)/(1
A thermal transfer recording method characterized in that recording is performed with -Cosα)<T_f<350W. (2) The thermal transfer recording method according to claim (1), wherein a thermal transfer ink containing resin is used as the thermal transfer medium. (3) The recording head is characterized in that the length from the end of the heating element to the end of the substrate is 250 μm or less, and the thermal transfer medium is separated from the recording medium at the end of the substrate. The thermal transfer recording method according to (1) or claim (2).