JP2979443B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image to be printed on a recording paper by sandwiching a printing tape and a recording paper between a head and a platen and controlling the heating, pressurizing and voltage application of the head according to image information. The present invention relates to a forming apparatus.

[0002]

2. Description of the Related Art Supply means for supplying a print tape, a head controlled in accordance with image information for printing on recording paper by the print tape sent from the supply means, and a print tape between the head and the head. A platen for supporting the recording paper and the recording paper, a conveying unit for nipping and conveying the printing tape from the printing position of the head and the platen, and a winding unit for winding the printing tape conveyed by the conveying unit. Image forming apparatuses are known.

[0003]

When the limiting torque of the take-up reel is T, the take-up radius is U, and the tension applied to the print tape by the take-up reel is V, the equation T = U × V is established. . Here, since T is constant, the winding radius U
Increases, the tension V applied to the printing tape decreases. As a result, it may not be possible to apply an appropriate tension to the printing tape at the printing position (where the head and platen overlap and support the printing tape and the recording paper), which may cause a problem of deterioration in printing quality. on the other hand,
If the width of the change in the tension applied to the printing tape is to be minimized, there arises a problem that the winding radius of the printing tape must be limited. SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus in which the tension applied to a printing tape is always kept constant irrespective of a change in the winding diameter of the printing tape to improve printing quality and eliminate the limitation on the winding radius. It is in.

[0004]

In order to achieve the above object, according to the present invention, a first torque limiter is provided on a winding means and a second torque limiter is provided on a conveying means.
The radius of the winding means is ro and the winding of the winding means is
The force for winding the printing tape at the start is fmax, the first
The limiting torque of the torque limiter of A is
The radius is R, and the force by which the transport roller transports the printing tape is
F, the limiting torque of the second torque limiter is B
And (F> fmax), the above ro,
Set A, R and B as (B / R)> (A / ro)
Was.

[0005]

The tension of the thermal transfer ribbon at the printing position is always kept constant even if the winding diameter of the winding reel changes.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 illustrates an example of an image forming apparatus that continuously prints many business cards by thermal transfer. This device is used by being connected to a personal computer (not shown). 1 is a casing. Reference numeral 2 denotes a paper feed mechanism 2 for feeding, for example, business card printing sheets (recording paper) one by one. Downstream of the paper feed mechanism 2, a receiving layer is formed on the surface of the sheet fed from the paper feed mechanism 2 by a thermal transfer using a pre-processing material such as a binder material, and then printing of characters, graphics, and the like is performed by the thermal transfer. A layer / image forming mechanism 3 is provided. Further, downstream of the image forming mechanism 3, a protective layer forming mechanism 4 for covering the protective layer with a transparent material or the like by thermal transfer on the surface of the image-formed sheet conveyed from the receiving layer / image forming mechanism 3 is provided. Have been.

A paper feed path 5 for conveying a sheet from the paper feed mechanism 2 to the receiving layer / image forming mechanism 3 is provided. Further, a paper discharge path 6 for conveying a sheet from the receiving layer / image forming mechanism 3 to the protective layer forming mechanism 4 is provided. Reference numeral 7 denotes a feed roller provided in the paper discharge path 6. Downstream of the protective layer forming mechanism 4, a paper discharge tray 8 for storing printed sheets is provided.

The paper feed mechanism 2 will be described with reference to FIG. 1 and FIG. Reference numeral 9 denotes a paper feed tray for stacking and storing sheets.
An alignment guide 10 that moves in the width direction of the paper feed tray 9 and aligns the sheet bundle is provided on a side portion of the paper feed tray 9. At the leading end of the paper feed tray 9, a paper feed tray 9 is provided.
A separation gate 11 is provided for separating and sending only one sheet from the gap between them. On the lower side of the paper feed tray 9,
A feeding roller 12 that feeds from the lowest sheet on the paper feed tray 9 is provided. A pair of feed rollers 13 is provided downstream of the paper feed tray 9. The feed rollers 13 are provided so as to be separated from each other and pressed against each other. Downstream of the feed roller 13, there is provided a pair of registration rollers 14 for abutting the leading edge of the sheet to correct the left-right bending (skew) of the leading edge of the sheet. A switching gate 15 for switching the transport path is provided downstream of the registration rollers 14. This switching gate 15
Is always urged by a spring 16 so as to close the paper feed path 5 and open the paper discharge path 6. The feed roller 12, the feed roller 13, the registration roller 14, and the like are connected to a second drive system described later. The sheet sensor 17 counts the number of fed sheets and detects the trailing edge of the sheet.

Next, the receiving layer / image forming mechanism 3 will be described with reference to FIG. 1 and FIG. 2 and FIG. Downstream of the switching gate 15, a pinch roller 19 is pressed in contact with a driven grid roller 18. The grid roller 18 has a large number of irregularities on its outer periphery so that the sheet can be fed without slipping. The pinch roller 19 moves on the outer periphery of the grid roller 18 following the operation of a platen 29 described later (FIGS. 2 and 3).
reference). The grid roller 18 and the pinch roller 1
Downstream of 9, a head 20 for heating according to image information at the time of thermal transfer is provided. The thermal transfer ribbon 21 and the sheet are superimposed between the head 20 and the platen 29 and thermally transferred in a state of being pressed against each other. Reference numeral 22 denotes a head cooling fan.

A supply means for supplying a printing tape, for example, a thermal transfer ribbon 21, for example, a feed reel 23, and a winding means, for example, a take-up reel 24, which winds the thermal transfer ribbon 21 drawn from the feed reel 23 after the printing point of the head 20 has passed.
Are provided. Further, at a position intermediate between the head 20 and the take-up reel 24, the head 20 and the platen 29 pull out and convey the thermal transfer ribbon 21 from a portion where the thermal transfer ribbon 21 and the sheet are overlapped and supported (hereinafter, referred to as a printing position). Transport means, for example, a pair of transport rollers 25 is provided. The take-up reel 24 and one of the transport rollers 25 (the roller located at the top of the figure) are driven and rotated by a motor 30. The take-up reel 24 is provided with a first torque limiter (not shown). Further, a second torque limiter (not shown) is provided on the transport roller 25 to be driven.

Now, the limiting torque (torque at which slipping starts) of the first torque limiter provided on the winding reel 24 is A, the winding ribbon radius of the winding reel 24 is r (small radius r1, large radius r2), and winding is performed. The pulling force of the take-up reel 24 is f
(F1 for r1, f2 for r2). By the way, the following general formula is established. f × r = A = constant Therefore, the following equation is established. f1 × r1 = f2 × r2 = A = constant As can be understood from the above equation, the pulling of the take-up reel 24 is performed.
When the tension f is obtained, f = A / r. From the above equation, it can be seen that as the winding diameter r increases, the ribbon pulling force f decreases. The transport rollers 25
Assuming that the limiting torque of the second torque limiter is B (constant) and the roller diameter is R (constant), the ribbon pulling force F by the transport roller 25 becomes constant. By the way, in the general formula described above,
When applied, F × R = B = constant, and similarly, F =
B / R is required.

By setting A and B such that the change in the ribbon tension due to the change in the winding diameter of the take-up reel 24 always becomes F> f, the ribbon tension in the printing portion is set to F ( Constant). That is, as described above
From the equation, the relationship between A and B is set as (B / R)> (A / r)
By doing so, the above-mentioned F> f is satisfied.

The thermal transfer ribbon 21 is formed such that, along the transport direction, one frame of a receiving material coated with a pretreatment material alone for improving the adhesion of the dye, and then dyes, for example, yellow, magenta and cyan in this order. A total of four frames of three coated frames (the binder may be included in the dye) are formed as one set, and a large number of sets are continuously provided.

At a position just before the printing point where the head 20 and the platen 29 are pressed against each other in the thermal transfer ribbon conveying direction, the sheet and the thermal transfer ribbon 21 are pressed in a planar manner by utilizing the waist of the curved sheet to form the thermal transfer ribbon 21. A tension roller 26 for removing wrinkles is provided.

A platen 29 is provided facing the head 20 so as to be able to press and separate according to the sheet feeding state. Thermal transfer ribbon 2 between head 20 and platen 29
1 and the sheet at an appropriate pressure, the thermal transfer ribbon 21 is moved from the left to the right in FIG. 1 with respect to the head 20 in accordance with the conveyance speed of the sheet sandwiched between the grid roller 18 and the pinch roller 19. Synchronously transport the thermal transfer ribbon 21
The upper one frame is thermally transferred. The sheet after the thermal transfer is returned from the right to the left in FIG. 1 with respect to the head 20 and the thermal transfer ribbon 21 is advanced by one frame.
1 is transferred from left to right in FIG. 1 to perform thermal transfer.

The pinch roller 19 is displaced following the platen 29.

Grid roller 18 and platen 29
Is driven by a first drive system including a motor 31, a belt 32, a pulley 33, and the like.

The sensor 34 determines the position at which the transfer of the point heat transfer ribbon is started. Next, the protective layer forming mechanism 4 will be described with reference to FIG.

At the end of the paper discharge path 6, a head 35 and a platen 36 are provided. Below that, a grid roller 37 and a pinch roller 38 are provided. The platen 36 is separated from the head 35 when a sheet is introduced and when the thermal transfer ribbon 43 is independently conveyed.

39 is a feed reel, 40 is a take-up reel,
41 is a conveyance roller, 42 is a tension roller. An appropriate tension is always applied to the thermal transfer ribbon 43 by using a torque limiter (not shown) for the transport roller 41 and the take-up reel 40. The configuration of the take-up reel 39 and the transport roller 41 is the same as the configuration of the take-up reel 24 and the transport roller 25 described above, and a description thereof will be omitted. A transparent material (post-processing material) that covers and protects the surface of the sheet image is applied to the thermal transfer ribbon 43. Reference numeral 46 denotes a paper discharge roller for discharging the printed sheet to the paper discharge tray 8. The take-up reel 40 and the transport roller 41 are driven by a motor 47. The grid roller 37 and the platen 36 are driven by a second drive system such as a motor 48, a belt 49, and a pulley 50. The motor 48 of the second drive system is connected to the feed roller 12 and the feed roller 13 in the paper feed mechanism 2 as described above.
Also, the registration roller 14 and the like are driven.

The control of the driving is performed by control means (not shown) such as a CPU. The sheet sensor 51 counts the number of printed sheets.

The operation of the above apparatus will be described with reference to FIGS. 1 to 4 and a time chart of FIG. 1. One sheet is placed between the separation gate 11 and the paper feed tray 9.
By sandwiching the sheets, the height of the separation gate 11 is adjusted. 2. Next, the sheets are stacked and stored in the paper feed tray 9, and the alignment guide 10 is moved to align the sheet bundle in the short direction. On the other hand, an image is input from an image scanner (not shown) to a personal computer (not shown), and the apparatus receives image processed image information and information such as the number of prints. 3. Next, the feeding roller 12 is driven to drive the separation gate 1.
The sheet is separated into one sheet and sent out. This sheet passes between the feed rollers 13 in the separated state, and strikes the registration rollers 14 in the stopped state to correct the skew. 4. Next, the sheet is conveyed by the feed roller 13 and the registration roller 14 sandwiching the sheet, and the switching gate 15 is pushed open to reach between the grid roller 18 and the pinch roller 19. At this time, the sheet sensor 17
Counts the number of fed sheets. This sheet is fed in the direction of the head while being sandwiched between the driving grid roller 18 and the pinch roller 19. At this time, the platen 29 is at a position separated from the head 20. 5. Next, the sheet is rotated by reversing the grid roller 18 as shown in FIG.
, The sheet sensor 17 detects the trailing edge of the sheet, counts a predetermined number of pulses, stops the grid roller 18, and positions the transfer of the sheet. 6. Next, the motor 30 drives the take-up reel 24 and the transport roller 25 to position the transfer start of the frame of the receiving material on the thermal transfer ribbon 21. 7. Next, the platen 29 is attached to the sheet and the thermal transfer ribbon 2.
1 is pressed against the head 20. 8. Next, the take-up reel 24, the transport roller 25, and the grid roller 18 are driven to synchronously transport the thermal transfer ribbon 21 and the sheet, and the head 20 is heated in accordance with image information, and the receiving layer is formed on the surface of the sheet by thermal transfer. To form Before the thermal transfer ribbon 21 reaches the printing position, the sheet and the thermal transfer ribbon 21 are overlapped by the stiffness of the curved sheet, and are conveyed in a state of being pressed by the tension roller 26. At this time, even if the take-up radius of the take-up reel 24 increases, the tension of the thermal transfer ribbon 21 at the printing position is always maintained at the tension F applied to the thermal transfer ribbon by the transport roller 25. 9. Next, the platen 29 is separated from the head 20 and retracted. Ten. Positioning of the start of thermal transfer of the sheet, positioning of the start of thermal transfer of the thermal transfer ribbon, pressing of the platen against the head,
The operations of thermal transfer and retreat of the platen from the head are repeated three times, and yellow, magenta, and cyan dyes are sequentially transferred to the receiving layer of the sheet, and images such as characters and figures are printed. While the receiving layer and the image are being formed on the first sheet in this way, the next second sheet is advanced to the position of the registration roller 14 and is kept on standby. 11． Next, the grid roller 18 and the feed roller 7 are driven to convey the sheet from the receiving layer / image forming mechanism 3 to the protective layer forming mechanism 4 via the paper discharge path 6. At this time,
The platen 29 is separated from the head 20. In addition,
As described above, when the first sheet is being conveyed through the paper discharge path 6, the aforementioned second sheet is conveyed to the receiving layer / image forming mechanism 3. 12． When a predetermined pulse is counted after the sheet sensor 52 detects the leading edge of the sheet, the sheet feeding is stopped and the position for starting the transfer of the protective layer is determined. 13. Next, positioning of the start of transfer of the protective layer of the thermal transfer ribbon 43, press-contact of the platen 36 to the head 35, thermal transfer, and separation and retreat of the platen 36 from the head 35 are sequentially performed to form a protective layer on the surface of the sheet image. Complete the business card.
At this time, even if the winding diameter changes, the tension on the thermal transfer ribbon 43 is kept constant as in the case of the above-described receiving layer / image forming mechanism. 14. Next, the sheet is discharged to the discharge tray 8 by the discharge roller 46. While the second sheet is forming the receiving layer and the image, the operation until the first sheet is discharged to the discharge tray 8 and the third sheet is transferred to the sheet tray 9 And the operation to advance to the position of the registration roller 14 is performed.

According to this embodiment, no matter how much the winding radius of the take-up reel 24 increases, the tension of the thermal transfer ribbon 21 at the printing position is always maintained at the tension F applied to the thermal transfer ribbon 21 by the take-up reel 24. In addition, the problem of poor printing due to uneven winding and the elasticity of the thermal transfer ribbon is eliminated. Further, even if the winding diameter increases, the tension of the thermal transfer ribbon 21 is kept constant, so that there is no need to limit the winding radius. The present invention is not limited to the above embodiments, and various embodiments can be implemented. For example, in the above embodiment, a thermal transfer device as an image forming apparatus, a heating control type as a head, and a thermal transfer ribbon as a print tape are shown. However, the present invention is not limited thereto. Can also be applied to a printing apparatus having Further, in the above-described embodiment, the reel type in which the printing tape is wound is shown as the printing tape supply means. However, the present invention is not limited to this. For example, a method in which a folded printing tape is pulled out may be used.

According to the present invention described above , the winding means is provided with the first torque limiter and the transport means is provided with the second torque limiter, and the power for transporting the printing tape by the transporting means is applied to the printing tape by the winding means. The limiting torque of the first torque limiter and the limiting torque of the second torque limiter are set so as to always be larger than the winding force. More specifically, let the radius of the winding means be r
o, winding the printing tape at the start of winding by the winding means
The force is fmax and the limit torque of the first torque limiter is
A, the radius of the transport roller is R, and the transport roller
The transfer force is F and the limit torque of the second torque limiter is
Assuming that B, the relation that satisfies (F> fmax) is
Note that ro, A, R and B are represented by (B / R)> (A / ro)
Is set. Therefore, even if the winding diameter of the winding means changes, the tension of the printing tape at the printing position is always maintained at a constant tension applied to the printing tape by the winding means, and uneven printing or poor printing due to the elasticity of the printing tape. Problem is solved. Further, even if the winding diameter increases, the tension of the printing tape is kept constant, so that there is no need to limit the winding radius.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an entire apparatus according to an embodiment of the present invention.

FIG. 2 is a partial operational view of the embodiment.

FIG. 3 is a partial operational view of the embodiment.

FIG. 4 is a perspective view showing a part of the embodiment.

FIG. 5 is a flowchart showing the operation of the embodiment.

[Explanation of symbols]

 Reference Signs List 2 paper feed mechanism 3 receiving layer / image forming mechanism 4 protective layer forming mechanism 20 head 21 thermal transfer ribbon (printing tape) 23 feed reel (supply means) 24 take-up reel (take-up means) 25 transport roller (transport means) 29 platen 30 motor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 17/02 B41J 2/325 B41J 13/02 B41J 33/14

Claims (1)

(57) [Claims] 1. A supply unit for supplying a print tape, a head controlled in accordance with image information for printing on recording paper by the print tape sent from the supply unit, and at least printing between the head. A platen that supports the tape and the recording paper in an overlapping manner; a transport unit that draws out and transports the printing tape from a printing position where the head and the platen support the printing tape and the recording paper in an overlapping manner; and a printing tape that is transported by the transporting unit And a winding means for winding the paper, wherein the winding means is provided with a first torque limiter and the transport means is provided with a second torque limiter, and the radius of the winding means is ro, Winding of winding means
The force for winding the print tape at the start of take-up is fmax,
When the limiting torque of the first torque limiter is A,
The radius of the roller is R, and the transport roller transports the print tape.
The force is F, and the limiting torque of the second torque limiter is B.
Then, the relationship that satisfies (F> fmax) is satisfied by the aforementioned r.
o, A, R and B are set as (B / R)> (A / ro)
An image forming apparatus characterized in that: