JPS61164869A - Image-forming device - Google Patents

Abstract

PURPOSE:To securely control transfer in conformity with feeding of a transfer recording material and to engine clear images to be formed at predetermined positions of the recording material, by controllingly correcting a detection level of a detecting means in accordance with a prestored reference detection level. CONSTITUTION:A paper detector (paper supply sensor) 40 is provided in the vicinity of a pair of aligning rollers 15, 15, and a paper leading end detector 41 is provided in the vicinity of a pinch roller 30 on the paper-discharging side. Each of the detectors 39, 40, 41 consists of a light-emitting element and a light-receiving element. The detector 41 is provided at a position opposed to a central part of a guide passage 31 on the paper-discharging side, namely, a central part of the pinch roller 30. Accordingly, in the case of detecting the leading end of the transfer recording material (cut paper Pa) by the detector 41, positional errors at end parts of the cut paper Pa are minimized, even if the detecting position is at a central part or an error is generated in the detecting position for the leading end of the paper Pa.

Description

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

[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 the Background Art] However, in the above-mentioned devices, in order to control paper conveyance, etc., detection of the leading edge of paper, detection of paper passage, etc. is performed using an optical detector consisting of a light-emitting element and a light-receiving element. are doing. Depending on whether the detection level of this detector is high level or low level, it is determined whether there is paper or not, that is, whether it is dark or bright. Therefore, if the detector output level decreases due to dust, etc. adhering to the detector,
There was a risk of misjudging light and dark. For this reason, there is a problem in that it is not possible to always reliably control the transfer in accordance with the conveyance of the paper, and it is not possible to form a clear image at a predetermined position on the paper.

[Purpose of the Invention] This invention was made in view of the above circumstances, and its purpose is to make corrections in accordance with the detection level at that time, even if the detection means becomes dirty due to long-term use, for example. Therefore, it is an object of the present invention to provide an image forming apparatus that can always perform reliable transfer control in accordance with the conveyance of the transfer material and can form a clear image at a predetermined position on the transfer material.

[Summary of the Invention] In order to achieve the above object, the present invention stores a reference detection level by a detection means for detecting a transfer material when the power is turned on, and performs detection by the detection means at this stored reference detection level. The level is corrected and controlled.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

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 and serve as a transfer material supply section, are disposed at the rear of the main body 1. . Also,
A platen roller 4 as a drive section for the transfer material is provided at a position corresponding to the mounting section of the paper ejection tray 2 in the main body 1, and a shaft of the 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 a line tod shape along the direction. Here, the thermal head 5 and the platen roller 4 constitute a transfer section 200. Further, near the circumferential surface of the platen roller 4, a paper feed side pinch roller 20 and a paper discharge side pinch roller 30 that can come into contact with and separate from this circumferential surface are provided. 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 stores a roll-shaped thermal transfer ribbon 6 as a transfer material so that it can be taken out, and a A ribbon winding section 8 is provided for winding up the thermal transfer 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 is then wound around the fourth ribbon guide 13 until the roll of the ribbon winding unit 8 ( It is configured to be wound around a winding core (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 and supplied from the cut paper supply cassette 3 via the feeding roller 16, or the manual feed tray 17
The cut paper Pb1 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 supply roller arranged so as to be in rolling contact with the cut paper supply cassette 3. It is configured to be fed between the paper side pinch roll 20 and the paper side pinch roll 20.

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

Further, between the cassette mounting section 22 and the pair of aligning rollers 15.15, there are first and second guide plates 24.
25 are arranged. Furthermore, a feeding roller 16 is provided for frictionally feeding the uppermost layer of cut paper Pa in the cut paper supply cassette 3, and the cut paper Pa fed by the feeding roller 16 is transferred 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 paper feed rollers 18.18 and the pair of aligning rollers 15.15, the third guide plate 27, which forms a manual paper guide path 26 for guiding the manual paper Pa, and 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 that form the paper discharge side paper guide paths 31 and 207 that guide the paper Pa, Pb, and pc sent out by normal rotation of the paper to the paper discharge 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, there are paper sheets Pa, Pb, and Pc.
A switchable gate plate 208 is installed so as to guide the vehicle 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 has a circumferential surface that protrudes from the aligning roller pair 15. A rotating body 212 made of a member is provided.

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 a central portion of the paper ejection measurement guide path 31, that is, at a position facing the center of the paper ejection side pinch roller 30. 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 not deviate from the proper leading edge detection position. Even if such deviation occurs, the deviation at the edge of the cut paper Pa is minimal.

FIG. 3 above is a view of the internal mechanism seen 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 a main drive source for driving the platen roller 4, etc., 44 is a pulse motor for paper feeding, and 46 is for ribbon winding and head contact/separation. A pulse motor 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 row 530 toward and away from the platen row 54, 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).

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 attached, recording is performed on the cut paper Pa. That is, in response to the recording command, the pulse motor 44 is driven and the driving force is transmitted as described later, the feeding roller 16 rotates clockwise, and the uppermost cut paper pa in the cut paper supply cassette 3 is taken out. Ru. The cut paper pa taken out from the cut paper supply cassette 3 passes through the second and third guide plates 25 and 27.
Aligning roller pair 15.1 with the leading edge of cut paper Pa passing through paper guide path 213 formed by
- It comes into contact with the rolling contact section 5, 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 350. 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 row 54, 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 helad 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 row 54 is rotated counterclockwise by the pulse motor 43, and the pulse motor 46 is rotated in the normal direction. The 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 row 54, 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 the 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. Thereafter, the platen roller 4 is rotated counterclockwise to a portion where the platen roller 4 and the paper discharge side pinch roller 30 are in contact with each other, and the cut paper pa is conveyed in the reverse direction. When this reverse conveyance is completed, the head cam 73 is operated to bring the thermal head 5 into pressure contact with the platen roller 4, and the thermal transfer ribbon 6 is rolled up by rotating the core 14 of the ribbon winding section 8 counterclockwise, and at the same time, the platen roller 4 is rotated clockwise, heating recording of the thermal head 5 begins. 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 passes through the paper ejection side paper guide path 31 formed between the guide plates 32 and 205, is conveyed to the front paper guide path 206 of the apparatus formed by the guide plates 205 and 33, and the cut paper P
The rear end of a is the platen roller 4 and the paper feed side pinch roller 20.
It is transported close to the area where it is in contact with the 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 counterclockwise. The cut paper Pa is reversely conveyed in the return paper guide path 34 formed between .36 and 36. During this time, the gate plate 208 is in contact with the guide plate 32 to close the paper discharge guide path 207, and the leading end of the cut paper Pa is being conveyed to the paper guide path 206 at the front of the apparatus.

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.
Then, 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.

FIG. 4 shows the thermal transfer ribbon 6. As shown in FIG.

This thermal transfer ribbon 6 has yellow (Y), magenta (M), cyan (C), black (B) ink portions 6a, approximately the same size as the paper (A4), along the running direction (arrow direction), 6b, 6c, and 6d are arranged sequentially. Furthermore, a transparent portion 6f is provided on the side edge of the thermal transfer ribbon 6 along the running direction. This light transmitting portion 6f is located between the light emitting element 37 and the light receiving element 38 of the ribbon detector 39. Further, barcodes 6Q, . . . , which serve as identification marks indicating the color of each ink portion 6 a, . . . are provided in the light-transmitting portion 6f.

The barcodes 6q, . . . are different for each color of ink, and these barcodes indicate the color of the ink, the type of ribbon, etc.

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.

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. Therefore, 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.
, cassette detector 66, thermal head 5 substrate temperature detector 106.106, print medium temperature detector 192, paper discharge detector 193, A/D converter 19.9, sub-control unit 194
An output signal from the Lord IIJI Part 11 191
supplies predetermined operation signals to the display/operation input section 42, sub-control section 194, thermal head 5, data buffer (memory) 185, and interface section 196 based on these signals, and also supplies predetermined operation signals from the main control section 191. The pulse motor 43, the ribbon winding pulse motor 46, the paper feeding pulse motor 44, and the ribbon feeding and reverse winding pulse motor 209 are controlled by the control signal.
, the gate plate 208, the driving solenoid 211, the fixing solenoid 210 of the ribbon storage section 7, 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, data buffer? 195 main 111111 part 191
Print data from an externally connected device 197 supplied via an interface section 196 is stored, for example, line by line in response to a control signal from the interface section 196, 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 control signal supplied from the main control section 191 and the print data supplied from the data buffer 195, and thermally transfers the ink onto the sheets Pa, Pb, and Pc. It has become.

The A/D converter 199 converts the electric signal supplied from the paper leading edge detector 41 into a digital value and outputs the digital value to the main controller 191.

Thereby, when the power is turned on, the main control section 191 stores the digital value, that is, the bright level, in an internal memory (not shown) as the reference detection level of the paper leading edge detector 41. The main control unit 191 then detects the paper leading edge detector 4.
When paper is detected in accordance with No. 1, this detection level is stored in an internal memory and compared with a reference detection level (bright level) to determine whether it is bright or dark.

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 unit 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. If the inputted print data is a print pattern, for example, it is directly stored in the data buffer 195, and if it is a character code, a code interface control circuit, a character generator, etc. (not shown) is used to create a character pattern. After being converted into , it 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). This bond, the platen roller 4, the feeding roller 16, and the pair of aligning rollers 15 and 15 are driven, and as shown in FIG.
is taken out from the cut paper supply cassette 3 and aligned by a pair of aligning rollers 15.15.

Further, the cut paper Pa 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 (Sr1). In such a state, the paper leading edge detector 41 detects the cut paper pa.
It is determined whether the tip of is detected (Sr5). 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 (Sr1). 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 in the paper guide path 34.

Furthermore, when the power is turned on, the detection output of the paper leading edge detector 41 is as follows.
The signal is supplied to the main control section 191 via the A/D conversion section 199. As a result, the master m+ unit 191 stores the reference bright level (detection level) of the paper leading edge detector 41 in an internal memory (not shown) based on the supplied digital value. Therefore, when the cut paper pa is transported, the main control unit 191 uses the detection output (B) of the paper leading edge detector 41 and the reference brightness level (
Brightness or darkness is determined by comparing the brightness level with A) and checking whether it is within the brightness level width (C).

After the printing start position of the cut paper Pa is set as described above, the thermal head 5 is pressed against the platen roller 4 (ST13), the thermal transfer ribbon 6 and the cut paper pa are conveyed (ST14), and as shown in FIG. Printing begins as shown in e). The main control unit 19 then continues until the end of printing (page synchronization signal or stop signal) is detected.
1 performs the above printing (ST1) as shown in FIG.
5.16). 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 cut paper Pa is conveyed backward again to the printing point (ST19.20.21). At this time, the cut paper pa is stored in the paper guide path 34 again.

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). As a result, if the color is not R holly, 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). After that, the thermal head 5 is pressed by the platen roller 4 (Sr24), and the thermal transfer ribbon 6 and cut paper pa are conveyed from the print start position (ST25>, and printing is started. Then, printing is completed (page synchronization signal or The main control unit 191 performs the above printing until a stop signal (stop signal) is detected (ST26).
．． 27). At the time of printing, as shown in FIG. 10(g),
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 controller 191 causes the thermal head 5 to
is separated from the platen roller 4 (ST28). Next, the main control unit 191 rotates the pair of paper ejection rollers 29 and 29 to release the cut paper Pa as shown in FIG. 10(h).
is delivered to the paper output tray 2 and is ejected (ST29)
. After this paper ejection is completed, the main control section 191 controls the solenoid 47.
48, the pinch rollers 20 and 30 are separated from the platen roller 4, and the transfer operation is completed (S
T30).

As mentioned above, even if dust etc. adheres to the paper leading edge detector or the output of the detector itself decreases due to aging, the brightness level when the power is turned on is used as a reference when paper is detected. There is a difference between the detection level of the paper and the paper detection level.

In the above embodiment, a case has been described in which the detection level of the paper leading edge detector is corrected, but the present invention is not limited to this, and the correction may be performed on other paper detectors.

[Effects of the Invention] As detailed above, according to the present invention, even if the detection means becomes dirty due to long-term use, it is corrected according to the detection level at that time, so that the conveyance of the transfer material is corrected. It is possible to provide an image forming apparatus that can always perform reliable transfer control in accordance with the transfer target, and can form a clear image at a predetermined position on a transfer material.

[Brief explanation of drawings]

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 details of the guide path, Figure 3 is a perspective view of the internal mechanism to explain the installation position of the paper leading edge detector, and Figure 4 is a perspective view of the internal mechanism to explain the installation position of the paper leading edge detector.
5 is a schematic sectional view of a cut paper supply cassette; FIG. 6 is a schematic sectional view illustrating the operation of supplying the transfer material to the transfer section; Figure 7 is a cross-sectional view schematically showing the configuration of the contact/separation drive section of the thermal head, Figure 8 is a block diagram showing the control system, Figure 9 is a flowchart for explaining the printing operation, and Figure 10 is the printing operation. A diagram for explaining the conveyance state of paper in
FIG. 11 is a flowchart for explaining the detection operation. 4...Platen roller, 5...Thermal head, 6
... Thermal transfer ribbon (transfer material), 6a - ... Ink section, 6q, ... Barcode, 7 ... Ribbon storage section,
8... Ribbon winding section, 9.14... Core (roll)
, Pa, Pb... cut paper (transfer 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...Control circuit, 70...Paper conveyance guide, 191...Main control section, 195...Data buffer, 200...Transfer section,
206...Front paper guide path. Applicant's agent Patent attorney Takehiko Suzue Figure 2 (A
) M45 40
41S Fig. 2 CB) Fig. 3 Fig. 5 ＼ Fig. 6 Fig. 7 Fig. 8 Fig. 10 Fig. 11

Claims (1)

[Claims] An image forming apparatus that forms an image by transferring a coloring material of a transfer material to a transfer material, comprising a moving means for moving the transfer material, and a detection means for detecting the transfer material when the moving means moves the transfer material. , characterized by comprising a storage means for storing a reference detection level by the detection means when the power is turned on, and a control means for correcting and controlling the detection level by the detection means using the reference detection level by the storage means. Image forming device.