JPH01267254A - Curl correcting device - Google Patents

Abstract

PURPOSE:To adjust the curl correcting ability by furnishing a speed adjusting means to adjust the transport speed ratio of two roller couples, a heating means to heat the curl correcting part, and a means to adjust the temp. of this heating means. CONSTITUTION:Each sheet is pinched and transported by a roller couple 8, paid off to between guides 14, 15, and transported on a curved path P under guidance of these guides 14, 15 and a curl correcting part 16. When the leading edge is pinched by another roller couple 11, the transport speed by the roller couple 11 is made greater than the transport speed by roller couple if the leading and trailing edges of the sheet are curling downward to cause transportation in tensioned condition, and the sheet moves while in pressure contact with the curl correcting part 16 to be corrected being squeezed in the direction opposite to the curling. At this time, current is impressed to the shaft 17 of the correcting part 16, and the heat emitted is transmitted to the sheet. The effect of curl correction is adjusted by adjusting the speed of at least either of the roller couples 8, 11 and/or the temp. of the shaft 17.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a curl correction device for correcting curls occurring in a sheet after toner has fixedly adhered thereto in an image forming apparatus such as a copying machine.

(Prior Art) Generally, in an image forming apparatus having an electrophotographic copying process, toner transferred from an electrostatic latent image carrier to a sort is heated and melted to be fixed on the sheet. What to do about the tendency of curling to either the front or back side due to the heat of the fixing device.

Curling causes stacking failure or jamming when the sorted sheets are discharged onto the paper discharge tray. In addition, in an image forming apparatus equipped with an editing mechanism such as so-called double-sided copying or composite copying, which forms an image on one side of a sheet and then forms the image again on the other side or the same side, the 1st [ ] and 22nd This causes a shift in the image, resulting in poor image quality.

Therefore, conventionally, as a device for straightening sheet curls,
There is a method proposed in Japanese Patent Application Laid-Open No. 60-50547.

This curl correction device is arranged between a pair of fixing rollers and a pair of paper ejection rollers that ejects a sheet fed out from the fixed n roller pairs, with respect to a line connecting the nip position of both roller pairs. An inflection path is provided that protrudes in the opposite direction to the curl direction of the sort to be fed out, and the sheet is conveyed under tension between the pair of fixing rollers and the pair of discharge rollers. It is a matter of correction.

(Problem to be Solved by the Invention) However, the curl degree and curl direction of a notebook are determined by various factors such as sheet properties (for example, tsubo M), fixing temperature, conveyance speed, and so on. The curl state of the sheet discharged from the forming device is not constant.

For this reason, in the curl correction device, since the curl correction section is fixed, the sheet curl cannot be sufficiently corrected.
Further, there was a problem in that the curl was corrected too much, causing the curl to curl in the opposite direction. In other words, conventional curl adjustment devices cannot perform correction according to the curl state.

(Means for Solving the Problems) The present invention has been made to solve the above problems, and
An explanation will be given with reference to the accompanying drawings showing one embodiment. A sheet on which toner has been heat-fixed is transferred between two pairs of rollers (8) and (I).
A curl straightening device that straightens the sheet while bending it in a direction opposite to the curling direction by conveying the sheet in a tensioned state using the paper sheet I) and pressing a curl straightening section (16) against the notebook being conveyed. In, 1. When the conveyance speeds of the two roller pairs (8) and (II) are respectively (V, ) and (Vt), adjust the conveyance speed ratio (nX-V2/V+). Speed adjustment means [
speed adjustment device (80)] (see Fig. 5), 11,
a heating means [shaft (17) which is a conductive resistor] provided in the curl straightening section (16); and iii. a temperature adjusting means [temperature Detection device (70)] (see FIG. 3).

(Function) In the curl straightening device (1) having the above configuration, the sheet is brought into pressure contact with the curl straightening section (16) and the roller pair (8),
(I l) and is conveyed under tension, and the curl is corrected by being squeezed by the curl correction section (16).

The effect of the curl correction is that the roller pair (8), (
+1) at least one of the speeds, and/or
The temperature can be arbitrarily adjusted by adjusting the temperature of the heating means [shaft (17)].

(Example) The present invention will be described below with reference to the accompanying drawings.

1 and 2 show a curl straightening device and a fixing device according to the present invention, in which (1) is a curl straightening device, (20) is a curl straightening device, and (20) is a curl straightening device.
is the fixing device.

As shown in Fig. 1, the housing (2) of the curl straightening device (1) is roughly composed of an upper cover (3) and a lower cover (4), and has side walls on the upstream and downstream sides in the sheet conveyance direction. are formed with opening guide portions (6) and (7), respectively.

The housing (2) includes an opening guide portion (6),
A pair of rollers (8) and (11) each consisting of a pair of parallel rollers pressed against each other is arranged on the side of (7).

The roller pair (8) is composed of rollers (9) and (10), and is rotated by a drive mechanism (not shown) in the direction of the arrow at a transport speed (Vl), while the roller pair (11) is rotated by a drive mechanism (not shown). It is composed of rollers (12) and (13), and the sheet conveyance speed (V,) thereof can be adjusted by a speed adjustment device (80) shown in FIG.

In the speed adjustment device (80), a speed setting section (81
) is provided on the operation panel, etc., and by manually operating it, the speed control unit (82) controls the motor (83).
) is adjusted. Further, the conveyance speed (V, ) is set higher than the conveyance speed (Vl) of the roller pair (8) on the upstream side, and
1) Appropriate tensile force is applied to the sheet conveyed between the two. However, when the tensile force exceeds a predetermined value, slippage occurs between the sheet and the roller (13), thereby preventing damage to the sheet.

A guide (
14) and (+5) are arranged, and between the rain sounds there is a downwardly curved inflection path (P
) is formed, and the upper guide (14) has a substantially central portion expanded in two directions to form a housing portion (Lla), in which a curl correction portion (16) is disposed.

This curl correction part (16) lowers the circumference of the conductive resistor (17) rotatably provided on the side walls (5), (5) on the back side of the housing (2). Friction layer (18)
As shown in FIG. 2, a pair of electrodes (19) and (+9) are in contact with both ends of the shaft (17).

The temperature of the shaft (17) is then adjusted by a temperature control device (70) shown in FIG.

The temperature adjustment device (70) includes a calculation section (71), a temperature setting section (72) provided on an operation panel, etc., and a shaft (70) that is a resistor.
a power control unit (73) that controls power supplied to 17);
It is composed of a detection section (74) and a temperature detection element (75) that detects the temperature of the sleeve (17).

In the temperature adjustment device (70) having the above configuration, the temperature signal of the shaft (17) detected by the temperature detection element (75) is input to the calculation unit via the detection unit (74).

On the other hand, a signal set from the temperature setting section (72) is manually input to the calculation section (71), and the power control section (73) is operated based on this and a signal manually input from the nQ detection section (74). As a result, the power supplied to the sleeve (I7) is adjusted.

On the other hand, in the fixing device (20), the housing (21)
There are opening guide parts (22
), (23) are formed. In addition, the housing (2
1), roller pairs (24) and (29) are arranged on the sides of the opening guide parts (22) and (23), respectively.

The roller pair (24) is a pair of parallel rollers (25).

(28), both of which are pressed into contact with the reins and rotated in the direction of the arrow by driving means (not shown), and the upper roller (25) has a built-in heater (26) as a heating means. A temperature detection sensor (
27) is the contact.

Another pair of rollers (29) is a pair of parallel rollers (
30) and (31), which are pressed against each other and driven to rotate in the direction of the arrow by respective driving means (not shown), and between the roller pair (24) and (29), Temporary guides (32) and (33) are provided.

The operations of the curl correction device (1) and fixing device (20) having the above configuration will be explained.

The sheet having the toner image on its upper surface is conveyed along the dotted line from the upstream side (left side) in FIG.
22) through the housing (21) of the fuser device (20)
When the toner is conveyed and nipped by a pair of rollers (24), the toner is melted and fixed by the heat of the heater (26).

Then, when the sheet is being held and conveyed by the pair of rollers (24), the leading and trailing ends of the sheet are protected by heat applied by the heater (26) and by pressure between the rollers (25) and (27). Curl in an upward or downward direction, respectively.

Note that the direction in which the curl occurs varies depending on the type of sorting, etc., but in this embodiment, the sorting is curled with the leading and trailing ends facing downward and the central portion convex upward.

Next, the sheet is conveyed to the right along the dotted line while being guided by temporary guides (32) and (33), and is conveyed to the right by the pair of rollers (29).
) through the opening guide part (23)
is discharged from.

Subsequently, the sheet is conveyed into the housing (2) via the opening guide part (6), conveyed between the pair of rollers (8), and pulled out between the guides (I4) and (15). ,
The sheet is conveyed along the curved path (P) while being guided by the guides (14), (15) and the curl correction section (16).

Then, when the tip is clamped by the roller pair (II), the conveyance speed (V, ) of the roller pair (II) is faster than the conveyance speed (Vl) of the roller pair (8). ,
While the sheet is conveyed in tension between the roller pairs (11) and (8), the sheet in such tension is transferred to the curl correction section (19) between the roller pairs (8) and (II). The curl moves while being in pressure contact with the curl, and is squeezed in the opposite direction to the curl direction to correct the curl.

In addition, in the curl correction section (16), the surface of the shaft (17) is coated with a low-friction layer (18), so the coefficient of friction with the notebook that moves while sliding on this surface is small, so that the surface of the shaft (17) is not fixed on the sheet. There is no need to scrape off the existing toner.

Further, an electrode plate (
A current is applied through +9) and (+9), which generates heat and transfers the heat to the sheet, further increasing the curl correction effect.

Note that the curl correction effect in the curl correction section (16) is achieved by the roller pair (8) and (11), as will be explained later.
The larger the tensile force based on the speed difference between the two and the higher the temperature applied to the sheet, the higher the tensile force.

However, if the speed difference and temperature factor are each made too large, the sheet will be damaged.

However, it may not be possible to correct curls sufficiently with just one of the factors.

Therefore, it is necessary to correct the curl by adjusting each of these within limits.

Specifically, in sheet straightening up to a predetermined degree of curl, the curl straightening effect is adjusted by fixing one element and changing the other remaining element. For sheet correction with a degree of curl greater than that, curl correction is performed by fixing the remaining elements to a value as large as possible within a range that does not damage the sheet, while changing the negative element. .

Hereinafter, the effects of the speed difference between the roller pairs (8) and (11) and the temperature of the curl correction section (16) on curl correction will be discussed.

Regarding the influence of the tensile horns of the sheet based on the speed difference on curl correction, the bending angle (0) of the sheet bent between the roller pair (8) and (I +) was fixed at 140°, and the water content was Using 5% sorting, roller pair (8)
Using the speed ratio (n) (-V t/V 1) of the conveyance speed (V, ) of the roller pair (ll) to the conveyance speed (V, ) of the roller pair (ll) as a parameter, this is n=1. l, 1.3.1.5
The degree of curl imparted to the sheet was measured by varying the temperature of the curl correction section (16) under the following conditions:
The results shown in FIG. 6 were obtained.

From this figure, it can be seen that the larger the speed ratio (n), the greater the degree of curl imparted to the sheet.

Next, regarding the influence of the temperature of the curl correction part (16) on the curl correction effect, the bending angle (θ) is set to 140°.
The speed ratio was fixed at n=1.3, and under these conditions, the degree of curl after straightening was measured by changing the surface temperature of each curl straightening part (16) for those with an initial curl degree of 0118.56. However, the results shown in Figure 4 were obtained. In the figure, back curl refers to a sheet with toner fixed on its top surface that is curled with its leading edge, rear end, or downward pointing. A curl with the tip and back pointing upwards.

From this figure, it can be seen that the higher the surface temperature of the curl correction section (16), the greater the degree of curl imparted to the sort.

In the above embodiment, a case where a curled sheet is corrected with the leading and trailing ends of the sheet pointing downwards is shown, but depending on the conditions of the sorting type N, the fixing device (20), etc., it may be corrected in the opposite direction. Curling may occur, and in this case, an upwardly curved inflection path is formed between the roller pairs (8) and (11), and the curl corrector (16) is brought into contact with the bottom surface of the note. .

Further, in the above embodiment, the conveyance speed of the roller pair (11) (
Although the roller pair (8 V, ) is made variable, the roller pair (8
) may be made variable, or both may be made variable.

(Effects of the Invention) As is clear from the above description, the curl straightening device according to the present invention includes a means for adjusting the tensile force of the sheet conveyed between two sets of rollers, a heating means, and a temperature adjusting device. The curl straightening ability can be adjusted by adjusting at least one of the tensile force and temperature.

Therefore, it is possible to adjust the relative speed of the roller pair by looking at the curl state of the sort that has passed through the curl straightening device, adjust the tensile force applied to the sheet, and adjust the temperature of the curl straightening section. , the sheet can be straightened into a curled state or a non-curled state as desired by the user.

However, by adjusting the tensile force and temperature to M11 within a range that does not adversely affect the sheet, it is possible to correct curls that cannot be corrected with the negative element alone.

Further, in an image forming apparatus equipped with an editing function, a high-quality edited image without any deviation can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the curl straightening device and the fixing device, FIG. 2 is a perspective view of the curl straightening device and the fixing device, and a circuit configuration diagram of the speed control, and FIG. 3 is a block diagram showing the configuration of the temperature control device. Figure 4 is a diagram showing the relationship between the curl straightening part temperature and the sheet curl degree, Figure 5 is a block diagram showing the configuration of the speed control device, and Figure 6 is a diagram showing the relationship between the curl straightening part surface temperature and the curl degree. It is a diagram. l... Curl correction device, 2... Housing, 5
...Side wall, 8.11...Roller pair, 9,
+ 0.12.13...Roller, 14.14...Guide, 16...Curl correction section, 17...Shaft (
Resistor), 18...Low friction layer, 19...Electrode plate, 20...Fixing device, 70...Temperature control device, 80...Speed control device. Patent originator Minolta Camera Co., Ltd. agent Patent attorney Maeda Ao is Chikarakawa name

Claims (1)

[Claims] (1) The sheet on which the toner has been heated and fixed is conveyed under tension using two pairs of rollers, and a curl correction section is pressed against the sheet being conveyed, so that the sheet is moved in the opposite direction to the curl direction. In the curl straightening device that straightens the curl while being bent, a speed adjusting means adjusts a conveying speed ratio of the two pairs of rollers, a heating means heats the curl straightening section, and a temperature adjuster adjusts the temperature of the heating means. A curl straightening device comprising a means.