JPS61154967A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To form a sharp image by preventing the generation of color shift, by applying division driving to a feed means for feeding a material to be transferred with respect to the transfer line unit of the material to be transferred. CONSTITUTION:The pulse motor 43 as the main drive source for driving a platen roll 4 moves (rotates) the platen roller 4 by 1/16mm by the one step rotation thereof. As a result, when the leading end of cut paper Pa is detected by a paper leading end detector 41, the paper feed amount l1 (1/16mm) per a step unit of the pulse motor 43 and the feed error l2 to a detection point 220 are 'l2<=l1' and the shift of each color of a thermal transfer ribbon 6 at a printing start point can be set to 1/2 or less a line unit feed amount l3 (1/8mm). As mentioned above, is the shift at the printing start point is set to 1/16mm, no color shift is felt visually and the prevention of color shift can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal transfer type image forming apparatus that is applied to, for example, output recording of a computer or word processor.

[Technical Background of the Invention] In recent years, as a non-impact printing technology, a thermal transfer type color (multicolor) image forming device has been developed that is small, inexpensive, noiseless, and capable of recording on plain paper. , has been put into practical use.

Normally, this type of image forming apparatus moves paper back and forth between a platen and a thermal head (thermal head) with a thermal transfer ribbon on which paper and ink of multiple colors are sequentially and repeatedly arranged. However, by operating the thermal head, the ink on the thermal transfer ribbon is sequentially transferred onto the paper to form an image.

[Problems with Background Art] However, in the above-mentioned device, a pulse motor is used to transport the paper, and the pulse motor is driven only one step for each line (1/8 mm) of transferring ink to the paper. was transporting the thermal transfer ribbon. For this reason,
Since the error in detecting the leading edge of the thermal transfer ribbon corresponds to the paper conveyance amount in step units (1/8 mm) of the pulse motor, there is a drawback that color misregistration occurs.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide an image forming apparatus that can prevent the occurrence of color shift and can form clear images. be.

[Summary of the Invention] In order to achieve the above-mentioned object, the present invention provides a conveyance means for conveying a material to be transferred. Refer to and explain.

FIG. 1 shows a thermal transfer type image forming apparatus of the present invention, and 1 in the figure is a main body. A paper discharge tray 2 is disposed on the upper surface of the main body 1, and a cut paper supply cassette 3 and a manual feed tray 17, which are attached to a cassette mounting section 22 as a transfer material supply section, are disposed in this dipping area. There is. Also,
A platen roller 4 as a drive unit for the transfer material is provided at a position corresponding to the mounting portion of the paper ejection tray 2 in the main body 1, and a platen roller 4 is provided below the platen roller 4. A thermal head 5 is provided as a thermal head in which a heat-generating portion (not shown) is formed in the shape of a line tod along the axial direction. Here, the thermal head 5 and the platen roller 4 constitute a transfer section 200. Further, near the surface of the platen roller 4, there are provided a paper feed side pinch roller 20 and a paper discharge side pinch roller 30 that can come into contact with and separate from the peripheral surface of the platen roller 4. The thermal head 5 is a line head in which heating elements for 1728 dots are arranged horizontally in a line at a density of 8 pieces/mm, and when using a multicolor ribbon, the thermal head 5 is a line head in which heating elements for 1728 dots are arranged horizontally in a line at a density of 8 pieces/mm. To prevent color shift, the processing time for one line is kept constant.

Further, as shown in FIG. 2(A), inside the main body 1 there is a ribbon storage section 7 that retractably stores a roll-shaped thermal transfer ribbon 6 as a transfer material, and a thermal transfer ribbon 6 that is fed out from the ribbon storage section 7. A ribbon winding section 8 is provided to wind up the ribbon 6 one after another.

The thermal transfer ribbon 6 is wound around the roll (winding core) 9 of the ribbon storage section 7 and fed out, and is sequentially wound around the first and second ribbon guides 10 and 11 and connected to the platen roller 4 and the thermal head 5. The ribbon is then guided through the third ribbon guide 12 so as to be sharply separated from the platen roller 4, and then wound around the fourth ribbon guide 13, and then the roll of the ribbon winding section 8 It is configured to be wound around a (winding core) 14.

On the other hand, a pair of aligning rollers 15 and 15, which are an example of registration rollers, are disposed above and behind the platen roller 4, as shown in FIG. The force for holding the transferred paper by this pair of aligning rollers 15.15 is:
This force is weaker than the paper pinching force between the platen roller 4 and the pinch roller 20 on the paper feed side or the pinch roller 30 on the paper discharge side. Furthermore, this aligning roller pair 15
．． The circumferential speed of 15 is set to be slower than the circumferential speed of the platen roller 4.

Also, cut paper pa as a transfer material (recording material) taken out from the cut paper supply cassette 3 via a feed roller 16 (described later) and supplied, or the manual feed tray 17
The cut paper Pb inserted from the manual supply roller pair 18, 18, or the roll paper PC which can be replaced with the cut paper supply cassette 3, is transferred to the platen roller 4 and the above-mentioned paper feed roller, which is electrically connected to the platen roller 4, is connected to the platen roller 4. It is configured to be fed between the paper feeding side pinch roll 20.

Note that the cut papers Pa, Pb, and roll paper Pc are both examples of transfer materials.

Further, between the cassette mounting section 22 and the aligning roller pair 15.15, there are first and second guide plates 24.
25 are arranged. Further, a feeding O for frictionally feeding out the uppermost layer of cut paper pa in the cut paper supply cassette 3 is provided.
- A roller 16 is provided, and the cut paper Pa sent out by the feeding roller 16 is fed to the aligning roller pair 15.1.
A paper guide path 210 leading to the third guide plate 27 and the guide plate 25 is formed between opposing surfaces of the third guide plate 27 and the guide plate 25. Also,
Between the pair of manual feed rollers 18.18 and the pair of aligning rollers 15.15, the third guide plate 27 forming a manual paper guide path 26 for guiding the manual paper pa is disposed opposite thereto. A fourth guide plate 28 is provided.

Furthermore, a pair of paper ejection rollers 29.29 is provided near the entrance of the paper ejection tray 2, and this pair of paper ejection rollers 29.29
A platen roller 4 is provided between the platen roller 4 and the platen roller 4.
5th, 6th, and 7th guide plates 32 forming the paper ejection side paper guide paths 31 and 207 that guide the paper Pa and PbSPc sent out by normal rotation of the paper to the paper ejection roller pair 29, 29.
．． 33.205 is arranged, and the paper Pa,
Front paper guide path 206 that guides Pb and PC to the front of the device
is formed. Between the paper ejection side paper guide path 31 and the paper ejection side paper guide path 207, the paper Pa1pb, pc
A switchable gate plate 208 is installed so as to guide the guide to either one of the guide paths 206 and 207.

Further, between the paper ejection side paper guide path 31 and the manual paper guide path 26, cut paper pa or manual paper pb fed from between the paper feed side pinch roller 20 and the platen 4 is placed in the paper ejection tray. A return paper guide path 34 is formed between the manual feed tray 17 and the manual feed tray 17. Here, the aligning roller pair 15.15 and the transfer section 200
A paper guide path 201 is formed between the lower end of the seventh guide 35 and the opposing surface of the paper transport guide 70 disposed opposite thereto. As shown in FIG. 2(B), this paper guide path 201 is provided with an elastic member that protrudes from the aligning roller pair 15. A rotating body 212' made of

Further, on the upstream side of the ribbon tensioning path, a ribbon detector 39 is provided to detect the ink (coloring material) compatible state of the thermal transfer ribbon 6. Said aligning roller pair 15.15
A paper detector (paper feed sensor) 40 is provided near the
A paper leading edge detector 41 is located near the pinch roller 30 on the paper ejection side.
are provided for each. Each of the above detectors 39.40.
41 is a well-known device consisting of a light emitting element and a light receiving element.

As shown in FIG. 3, the paper leading edge detector 41 is provided at the center of the paper guide path 31 on the paper ejection side, that is, at a position opposite to the center of the pinch roller 30 on the paper ejection side. As a result, when the paper leading edge detector 41 is used to detect the leading edge of the transfer material (for example, cut paper Pa), the detection position will be at the center, and the cut paper Pa will be shifted to the appropriate leading edge detection position. Even if this occurs, the deviation at the edge of the cut paper pa is minimal.

Therefore, when an image is formed using a multicolor ribbon using this detection means, color shift can be minimized and a clear image can be reliably formed at a prescribed position.

FIG. 3 above is a view of the internal mechanism viewed from below to explain the installation position of the paper leading edge detector 41.

In FIG. 1, 42 is a display/operation input unit, 43 is a pulse motor as the main drive source that drives the platen roller 4, etc., 44 is a pulse motor for paper feeding, and 46 is a ribbon winding and head contact/separator. 209 is a pulse motor for feeding out the ribbon and for reverse winding. Further, 47 and 48 are plunger type solenoids that move the paper feed side pinch roller 30 toward and away from the platen roller 4, and 211 is a plunger type solenoid that opens and closes the gate plate 208 with respect to the guide paths 206 and 207. 210 is a flapper type solenoid that transmits and interrupts the driving force of the pulse motor 209 to the winding core 9 of the ribbon storage section 7, 49 is a power supply section, and 50 is a control circuit. As will be described later, this control circuit 50 is connected to equipment housed within the main body 1 and is also connected to external equipment (not shown).

The pulse motor 43 is adapted to move (rotate) the platen roller 4 by 1/16 mm in contrast to one step drive. Thereby, as the platen roller 4 moves, the cut paper Pa is moved by 1/16 mm.

Therefore, as mentioned above, since the thermal head 5 prints at a density of 8 lines/mm, one line is printed in two steps of the pulse motor 43, and 8×8/mm is printed.
Printing is performed at a resolution of 7FLyd. As a result, when the paper leading edge detector 41 detects the leading edge of the cut paper Pa, as shown in FIG.
mm) and the feed error 12 for the detection point 220 is [12
≦lIJ, and the deviation of the printing start point of each color of the thermal transfer ribbon 6 is 1 of the line unit feed amount + 3 (1/8 mm).
/2 or less. In this way, the deviation of the printing start point can be reduced by 1
/16 mm or less, color shift will not be felt as far as the human eye can see, and color shift can be prevented.

As shown in FIG. 5, the cut paper supply cassette 3 has a magnet 65 on the front frame 61a of the cassette body 61.
is embedded, and the position of this magnet 65 is determined by a detector (reed switch) installed in the cassette mounting part 22.
By magnetically detecting the cassette 66, it is possible to automatically detect that the cassette is a cut paper supply cassette.

For example, when a recording command is supplied from an external computer or a word processor, this device operates, and when the cut paper supply cassette 3 is installed, the information is recorded on the cut paper pa. That is, in response to a recording command, the pulse motor 44 is driven and a driving force is transmitted as described later, and the feeding roller 16 is rotated clockwise, and the uppermost cut paper pa in the cut paper supply cassette 3 is taken out. be done. The cut paper pa taken out from the cut paper supply cassette 3 passes through the second and third guide plates 25.2.
The aligning roller pair 15 passes through the paper guide path 213' formed by 7 and the leading edge of the cut paper pa is stopped.
．． 15, and the leading edge of the cut paper pa is aligned here.

Thereafter, the aligning roller pair 15.15 is driven by the pulse motor 43 and advances between the paper conveyance guide 70 and the seventh guide plate 35. At that time, as shown in Figure 6,
The paper feed side pinch roller 20 is pressed toward the platen roller 4 (in the six directions of arrows) by the solenoid 47, and the paper discharge side pinch roller 30 is pulled in the direction of arrow B by the solenoid 48 and separated from the platen roller 4.

Here, as described above, the aligning roller pair 15
．． The peripheral speed of No. 15 is slower than the peripheral speed of platen roller 4. Therefore, the material to be transferred is the aligning roller pair 15.15, the platen roller 4, and the paper feed side pinch roller 2.
0, and can absorb the deflection of the transferred material while conveying the transferred material. Moreover, since the clamping force of the transferred material by the aligning roller pair 15.15 is made weaker than the clamping force of the transferred material by the platen roller 4 and the paper feed side pinch roller 20, the platen roller 4
The transfer material can be conveyed while being stretched at a conveyance speed of .

On the other hand, at this time, the thermal head 5 is displaced in the direction of arrow C and is separated from the platen roller 4 because the convex portion of the heald cam 73 is lowered, as shown in FIG. Then, the pulse motor 46 is reversed to raise the convex portion of the head cam 73 to press the thermal head 5 against the platen roller 4, the platen roller 4 is rotated counterclockwise by the pulse motor 43, and the pulse motor 46 is rotated forward. Then, the winding core 14 of the ribbon winding section 8 is rotated clockwise, and the cut paper pa is advanced in the D direction by the platen roller 4 and the thermal transfer ribbon 6. Near the top of the paper discharge side pinch roller 30, the paper leading edge detector 41 for detecting the leading edge of the cut paper pa is provided. This paper leading edge detector 4
1, when the leading edge of the cut paper Pa is detected, the rotation of the pulse motor 46 is stopped, and the conveyance of the thermal transfer ribbon 6 is stopped.

Further, the pulse motor 46 is reversely rotated to lower the convex portion of the head cam 73 to release the thermal head 5 from the platen roller 4, and the solenoid 48 presses the paper discharge side pinch roller 30 against the platen roller 30. In this state, the platen roller 4 is rotated counterclockwise by the pulse motor 43.

In this way, the cut paper Pa is wound along the circumferential surface of the platen roller 4 without being bent between the aligning roller pair 15.15 and the paper discharge side pinch roller 30.

Then, the cut paper Pa is transferred to the paper discharge side paper guide path 31 mentioned above.
After conveying the cut paper Pa to the front paper guide path 206 by the printing area, the pulse motor 43 is reversed to rotate the platen roller 4 counterclockwise, and the cut paper Pa is transported to the E shown in FIG.
While being conveyed in a reverse direction, the cut paper pa is guided to the return paper guide path 34 formed between the guide plates 35 and 36, and the leading edge of the cut paper pa is detected by the paper leading edge detector 41 described above. After that, the paper is blown and the cut paper pa is conveyed in the reverse direction. When this reverse conveyance is completed, the head cam 73 is operated to thermally rotate and wind the paper, and at the same time, the platen roller 4 is rotated clockwise, and heating recording of the thermal head 5 is started. That is, in this portion, the ink on the thermal transfer ribbon 6 is heated and melted by the thermal head 5 and transferred to the cut paper pa. The transferred cut paper pa is on the guide plate 32.205
The sheet guide path 20 at the front of the device formed by the guide plates 205 and 33 passes through the sheet discharge side sheet guide path 318 & formed between
6, and the rear end of the cut paper pa is transported to near the part where the platen roller 4 and the paper feed side pinch roller 20 are in contact with each other. Thereafter, the pulse motor 46 is stopped to stop conveyance of the thermal transfer ribbon 6, the RAD cam 73 is operated to release the thermal head 5 from the platen roller 4, and the platen roller 4 is rotated in the direction of the guide plate 3. The cut paper Pa is reversely conveyed in the return paper guide path 34 formed between . Insert the tip into the paper guide path 20 at the front of the device.
6.

The same operation as described above is repeated for the number of colors of the thermal transfer ribbon 6, but when printing the last color, the solenoid 211 is energized to move the gate plate 208 to the guide plate 3.
The paper is moved away from the guide plate 205 to open the paper ejection guide path 207, close the device front guide path 206, guide the cut paper Pa to the paper ejection roller pair 29, 29, and eject the paper to the paper ejection tray 2. do.

The thermal transfer ribbon 6 is wound up by a pulse motor 46 at a ribbon winding section 8 from a ribbon feeding section 7 via a ribbon guide 10, 11, 12, 13.

In the vicinity of the ribbon guide 10, the ribbon detector 39 is provided which can detect the type of thermal transfer ribbon 6 or the color of the thermal transfer ribbon 6. The ribbon detector 39 is composed of a light emitting element 37 and a light receiving element 38.The thermal transfer ribbon 6 is provided with a 4-bit barcode for each ink, and the combination of these 4-bit barcodes enables thermal transfer. The type and color of the ribbon 6 are detected.

Further, in order to set the color limit of the thermal transfer ribbon 6 near the printing point, a rotary encoder 90 and a detector 91 are provided near the ribbon guide 13 (see FIG. 2).
See A). The rotary encoder 90 rotates as the thermal transfer ribbon 6 moves, and the conveyance distance of the thermal transfer ribbon 6 can be detected by the holes provided in the rotary encoder 90 and the detector 91. The leading end is brought close to the printing point 93 and initial setting is automatically performed. Furthermore, the type of thermal transfer ribbon 6 can be automatically determined, the mechanism control mode can be changed, and the printing range can be changed. In particular, when the thermal transfer ribbon 6 is a monochrome transfer paper, printing can be performed over a wider range than the printing range of the multicolor thermal transfer ribbon 6.

Further, when a multicolor thermal transfer ribbon 6 is used, when the print signal reaches a specified color of the thermal transfer ribbon 6, the printed pattern of the specified color is skipped and conveyed on the thermal transfer ribbon 6. In particular, when using a four-color thermal transfer ribbon (black B1 yellow Y1 magenta M1 cyan C), if printing starts with black ink and ends with yellow ink, 1 cyan C ink is skipped between magenta and conveyed. to enable printing from the next black ink.

The relationship between the platen roller 4 and the thermal head 5 requires repeated press contact and release in order to convey the sheets Pa, Pb, and Pc. As shown in FIG. It is composed of a head cam 73 that presses into contact with the head cam 73, a pulse motor 46 that rotationally displaces the head cam 73, and a detector 212 that detects the rotational displacement of the head cam 73. As a result, the head cam 73 is driven by the pulse motor 46.
The thermal head 6 is brought into pressure contact with the platen roller 4 by rotating the convex part upwardly, and the head cam 7 is pressed against the platen roller 4.
As the convex portion 3 moves downward, the thermal head 6
is released from the platen roller 4. The detector 212 is composed of, for example, a light emitting element and a light receiving element, and detects the rotational displacement of the head cam 73 depending on whether or not the convex part of the head cam 73 is located between them, that is, whether or not it blocks light. ing.

Next, the control circuit 50 will be explained. In FIG. 8, a main control section 191 as a control means receives control signals from a display/operation input section 42 and various sensors, namely a ribbon detector 39, a paper detector 40, and a paper leading edge detector 41.
, a cassette detector 66, a substrate temperature detector 106, 106 of the thermal head 5, a print medium temperature detector 192, a paper discharge detector 193, and a sub-control unit 194. The main control unit 191 displays/displays based on these signals.
Operation input unit 42, sub-control unit 194, thermal head 5,
In addition to supplying a predetermined operation signal to the data buffer (memory) 185 and interface section 196, the pulse motor 4 is controlled by a control signal supplied from the main control section 191.
3. Pulse motor 46 for ribbon winding and head contact/separation
, paper feeding pulse motor 44, ribbon feeding and reverse winding pulse motor 209, gate plate 208, driving solenoid 211, ribbon storage section 7 fixing solenoid 210
, the driving solenoid 47 of the pinch roller 20, and the driving solenoid 48 of the pinch roller 30 are each set to a predetermined operating state. Also, in the data buffer 195, the interface unit 1
The print data from the external connection device 197 supplied via the external connection device 96 is stored, for example, line by line, and the stored print data is supplied to the thermal head 5. The thermal head 5 melts the ink on the thermal transfer ribbon 6 according to the IIJi[l signal supplied from the main control unit 191 and the print data supplied from the data buffer 195, and
It is designed to be thermally transferred to

Further, the interface section 196 is connected to the main control section 191.
It transmits and receives signals between the external connection device 197 and the external connection device 197. From the interface section 196 to the external connection device 19
7 is supplied with a vertical synchronization signal (page synchronization signal), a horizontal synchronization signal, a clock signal, and a status signal indicating the operating status of the main body 1, and commands such as a start signal, stop signal, color designation signal, etc. are supplied from the external connection device 197. Signals and print data are supplied. For example, if the input print data is a print pattern, it is directly stored in the data buffer 195, and if it is a character code, a character code is created using a hood interface control circuit, a character generator, etc. (not shown). The converted data is stored in the data buffer 195.

Next, in this configuration, the printing operation will be explained with reference to the flowchart shown in FIG. 9 and the state diagrams shown in FIGS. 10(a) to (h).

- As an example, a printing operation using cut paper pa will be explained. Note that the detection of cut paper pa is as described above.

For example, when a start signal is supplied from the externally connected device 197 to the main control section 191, the main control section 191 excites the solenoid 47 and drives the pulse motors 43 and 44. As a result, the pinch roller 20 is pressed against the platen roller 4 (ST1). Thereafter, the platen roller 4, feeding roller 16, and aligning roller pair 15.15 are driven, and as shown in FIG. 10(a), the cut paper Pa
is taken out from the cut paper supply cassette 3 and aligned by a pair of aligning rollers 15.15.

Further, the cut 41tPa is sent between the pinch roller 20 and the platen roller 4 (Sr2).

On the other hand, when the paper detector 40 detects the leading edge of the cut paper Pa and a predetermined period of time has elapsed, the main control unit 191 excites the solenoid 210, and the pulse motor 46.2
09, the winding core 14 of the ribbon winding section 8 is
and the core 9 of the ribbon storage section 7 rotates. As a result, the cut paper Pa and the thermal transfer ribbon 6 are conveyed in close contact with each other (Sr3). At this time, the thermal head 5 is pressed against the platen roller 4 in advance by driving the pulse motor 46 by the main control section 191 (Sr4). In such a state, the paper leading edge detector 41 detects the cut paper Pa.
It is determined whether the tip of is detected (Sr1). As a result, if the leading edge of the cut paper pa is not detected, the conveyance of the cut paper Pa is continued (Sr6). Also, Fig. 10 (b
), when the leading edge of the cut paper pa is detected by the paper leading edge detector 41, the main controller 191 excites the solenoid 48 and drives the pulse motor 46 in the reverse direction. As a result, the pinch roller 30 is pressed against the platen roller 4 (Sr7), and the thermal head 5 is separated from the platen roller 4 (Sr8). Next, the platen roller 4 is rotated forward by the main control unit 191, and the cut paper pa is conveyed by the printing area (Sr9). As a result, the cut paper Pa is conveyed to the front paper guide path 206 while removing the deflection, as shown in FIG. 10(C). The platen roller 4 is then reversely rotated by the main control unit 191, and the cut paper pa is reversely conveyed to the printing point (STIOll, 12), as shown in FIG. At this time, the cut paper Pa is stored between the paper guide paths 35 and 361. After the printing start position of the cut paper pa is set in this way, the thermal head 5 is pressed against the platen roller 4 (ST13), and the thermal transfer ribbon 6 and the cut paper Pa are conveyed (ST14). Printing starts as shown in FIG. 15. Then, the main control unit 191 performs the printing as shown in FIG. ).During this printing, the cut paper Pa is conveyed to the front paper guide path 206.

When the end of printing is detected, the main control unit 19
1, the thermal head 5 is separated from the platen roller 4 (ST17). Next, the main control section 191 drives the pulse motor 46 to transport the thermal transfer ribbon 6 to the printing point of the next color (ST18). In addition, the main control unit 191 causes the platen roller 4 to rotate in the reverse direction, and
), the cutter paper Pa is again conveyed backwards to the printing point (ST19.20.21). At this time, the cut paper Pa is again stored between the paper guide paths 35 and 36. Then, the main control unit 191 determines whether the next printing to be performed is the final color of all the colors designated by the color designation signal (Sr22
), and as a result, if the color is not the final color, steps 13 to 22 are repeatedly executed.

Also, if it is determined in step 22 that it is the final color,
The main control unit 191 excites the solenoid 211 to move the gate plate 208, close the device front guide path 206, and open the paper discharge guide path 207 (Sr23). Thereafter, the thermal head 5 is pressed by the platen roller 4 (Sr24), the thermal transfer ribbon 6 and the cut paper pa are conveyed from the printing start position (Sr25), and printing is started. Then, the main control unit 191 performs the above printing until the end of printing (page synchronization signal or stop signal) is detected (Sr26
．． 27). During this printing, as shown in FIG. 10 (1), the cut paper Pa is conveyed through the paper guide path 207 and guided to a pair of paper discharge rollers 29 and 29. When the end of printing is detected, the main control section 191 causes the thermal head 5 to move away from the platen row 54 (Sr28). Then,
The main control unit 191 rotates the pair of paper ejection rollers 29 and 29, so that the cut paper Pa is delivered to the paper ejection tray 2 and ejected as shown in FIG. 10(h) (ST29>).

After this paper ejection is completed, the main control unit 191 controls the solenoid 47.4.
8, the pinch roller 20.30 is separated from the platen roller 4, and the operation is completed (ST30
).

Note that in the above embodiment, the pulse motor is driven for two steps to convey the paper for one line, but the number of steps is not limited to this, and the number of steps may be further increased, and the color shift becomes smaller as the number of steps increases.

[Advantageous Effects of the Invention 1] As described in detail above, according to the present invention, it is possible to provide an image forming apparatus that can prevent the occurrence of color shift and can form clear images.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus, FIG. 2(A) is a schematic sectional view showing a transfer material supply section, and FIG. B) is a schematic sectional view showing the details of the guide path, FIG. 3 is a perspective view of the internal mechanism to explain the installation position of the paper leading edge detector, and FIG. 4 is a diagram explaining the relationship between the leading edge detection position and its deviation. Figure 5 for
6 is a sectional view schematically showing the rotated structure, FIG. 8 is a block diagram showing the control system, and FIG. 9 is a flowchart for explaining the printing operation. FIG. 10 is a diagram for explaining the printing state in the printing operation. 4...Platen roller, 5...Thermal head, 6
... Thermal transfer ribbon (transfer material), 7 ... Ribbon storage section, 8 ... Ribbon winding section, 9.14 ... Core (roll), Pa, Pb ... Cut paper (transferred material) Material), PC...
・Roll paper (transferring material), 29.29...Paper discharge roller pair, 31.207...Paper discharge side paper guide path, 32.33
．． 205... Guide plate, 39... Ribbon detector, 4
0... Paper detector, 41... Paper leading edge detector, 43
．． 44.46.209...Pulse motor, 47.48
．． 210.211... Solenoid, 50... Division circuit, 70... Paper conveyance guide, 191... Main control unit, 195... Data buffer, 200... Transfer unit,
206...Front paper guide path. Figure 2 (A) Figure 2 (B) Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (2)

[Claims] (1) An image forming apparatus that sequentially transfers a plurality of color materials of a transfer material to a transfer material to form an image, which includes a conveying means for conveying the transfer material to an image forming means, and a transport means for conveying the transfer material to the image forming means. 1. An image forming apparatus comprising: a drive unit that performs divisional driving for each line of transfer of a transfer material. (2) The image forming apparatus according to claim 1, wherein the transfer material moves back and forth through an image forming means.