JPH0668054U - Heat fixing device - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the leading edge of the paper sent by the upstream roller of the heat generating element is in contact with the heat generating element even before it is caught in the downstream roller, heat fixation is ensured. A fixing device is provided. [Structure] By moving the upper roller 2 of the upstream rollers 2 and 3 to a position slightly upstream of the conventional roller position to shift the position, the leading end of the paper 6 is placed on the lower surface of the heating element 1. It is configured to be sent to contact.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device mainly used for a printing device, and more particularly to a contact type heat fixing device.

[0002]

[Prior art]

 Conventionally, in a printing device that uses toner or solid ink as a printing medium, in order to fix the printing medium to a sheet of paper, etc., a heat fixing device that melts the printing medium by heating and penetrates it between the fibers of the sheet. It is generally equipped with.

As shown in FIG. 3, this type of heat fixing device has a heating element 1, a pair of rollers 2.3 on the upstream side, and a pair of rollers 4,5 on the downstream side. The two pairs of rollers 2, 3, 4 and 5 are arranged so that the pair of rollers 6 sandwich the sheet 6 on the upstream side and the downstream side of the heating element 1 in the sheet feeding direction. Then, in the printing unit 8 on the upstream side, characters, figures, etc. are formed by the printing medium on the paper 6, and the rollers 2 and 3 on the upstream side of the two sets of rollers send the characters onto the heating element 1. The print medium is melted and fixed by the heat of the heating element 1, and then discharged by the rollers 4 and 5 on the downstream side. Reference numeral 7 in the drawing is a paper guide.

When the print medium is melted by the heat of the heating element 1, the sheet 6 is brought into contact with the heating element 1 so that the heat is efficiently transferred to the sheet 6. Therefore, as shown in FIG. 4, the paper feed speed V1 of the downstream rollers 4 and 5 is set to be higher than the paper feed speed V2 of the upstream rollers 2 and 5 by about 5%, and the speed difference between the two sets It is general that tension is applied to the paper 6 between the rollers to surely bring the paper 6 into contact with the heating element 1. Further, the heating element 1 was also arranged so as to come into contact with the paper 6 while the paper 6 was tensioned.

[0005]

By the way, in the thermal fixing device of the above sort order, since the heating element 1 is disposed between the upstream side rollers 2 and 3 and the downstream side rollers 4,5, both sets of heat fixing devices are arranged. It is necessary to provide a distance of several tens of millimeters between the rollers 2.3 and 4.5, but in the conventional heat fixing device, the heating element 1 is attached to the paper 6 in the state where the tension acts as described above. They are arranged so that they come into contact with each other. Therefore, the paper 6 sent by the upstream rollers 2 and 3 onto the heating element 1 is not tensioned until the leading edge of the paper 6 is bitten by the downstream rollers 4 and 5, as shown in FIG. For several tens of millimeters from the tip of the sheet (the distance between the upstream side roller and the downstream side roller), contact with the heating element 1 was not sufficiently performed, and there was a risk that thermal fixing would be incomplete.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reliably generate heat even before the leading edge of the sheet fed by the upstream roller of the heating element is caught in the downstream roller. It is an object of the present invention to provide a heat fixing device that contacts the sheet and heat is reliably fixed on the entire surface of the sheet.

[0007]

[Means for Solving the Problems]

 In order to achieve this object, the heat fixing device of the present invention is provided with a heating element for fixing a print medium on a sheet, and a first sheet conveying device arranged upstream of the heating element for feeding the sheet to the heating element. Means and a second paper conveying means arranged downstream of the heating element for feeding the sheet from the heating element to a sheet slightly faster than the sheet feeding speed by the first sheet conveying means. The one sheet conveying unit is configured such that the leading end of the sheet conveyed by the conveying unit contacts the heating element.

[0008]

[Action]

 According to the heat fixing device of the present invention having the above-mentioned configuration, the leading end of the sheet fed to the heating element by the first sheet conveying means arranged upstream of the heating element contacts the heating element, While sufficiently transmitting heat, the heat is sent to the second sheet conveying means arranged on the downstream side. Then, when the sheet is caught in the second sheet conveying means arranged on the downstream side of the heating element, the sheet is tensioned due to the difference in the sheet feeding speed between the upstream side and the downstream side (the downstream side is slightly faster than the upstream side). Is activated, the paper becomes taut and contacts the heating element more reliably. In this way, the print medium is heat-fixed over the entire surface of the paper, including the leading edge.

[0009]

【Example】

 An embodiment of the heat fixing device of the present invention will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a partial cross-sectional front view for explaining the structure of a printing apparatus including a heat fixing device of this embodiment. As shown in FIG. 1, the printing apparatus includes a paper feeding unit 21, a printing unit 12, a heat fixing unit 13, and a paper discharging unit 15 in order. The paper feed unit 21 is configured by the paper feed cassette 20, the paper feed roller 9, and the like. The printing unit 12 includes a print head 8, a platen 11 and the like, the heat fixing unit 13 includes the heating element 1, and the paper discharge unit 15 includes paper discharge rollers 16 and 17, a paper receiver 18 and the like. .

The paper feed roller 9 feeds the paper 6 stacked in the paper feed cassette 20 onto the platen 11 in the printing unit 12. On the platen 11, the print head 8 applies the print medium to the paper 6 in a character shape or a graphic shape, and further, the print medium is sent to the heat fixing section 13 via a plurality of transport rollers.

The heat fixing unit 13, that is, the heat fixing device 13 has a pair of rollers 2 and 3 as the first sheet conveying means on the upstream side with the heating element 1 interposed therebetween and on the downstream side, similarly to the conventional apparatus. And a pair of rollers 4 and 5 as a second sheet conveying means. Further, a guide 7 is arranged between the lower rollers 3 and 5. However, by moving the upper roller 2 of the rollers 2 and 3 on the upstream side to a position slightly upstream of the conventional roller position (represented by a dotted line) as shown in FIG. It is configured so that the front end of 6 is brought into contact with the lower surface of the heating element 1. Instead of shifting the upper roller 2 to the upstream side, the lower roller 3 may be shifted to the downstream side and brought close to the guide 7. In short, the pair of rollers 2 and 3 on the upstream side may be arranged so that the leading end of the sheet 6 contacts the lower surface of the heating element 1 and is fed slightly upward. That is, the rollers 2 and 3 may be arranged so that the line perpendicular to the line connecting the centers of the pair of rollers 2 and 3 faces the heating element 1.

In the heat fixing device 13 of the present embodiment, as shown in FIG. 2, the sheet 6 conveyed by the rollers 2 and 3 on the upstream side faces upward, and the leading end of the sheet 6 contacts the heating element 1. Furthermore, if the paper 6 advances further and its leading edge is caught in the downstream rollers 4 and 5, the paper 6 will form on the paper 6 due to the speed difference between the upstream rollers 2 and 3 and the downstream rollers 3 and 4 as in the conventional case. A tension is applied, and the tension makes the paper 6 contact the lower surface of the heating element 1 more strongly. By the way, in the above-described embodiment, the state in which the sheet 6 is fed from the upstream side rollers 2 and 3 and is caught by the downstream side rollers 4 and 5 has been described. However, the rear end portion of the sheet 6 is located at the upstream side rollers 2 and 3. 3 of the downstream rollers 4 and 5 so that the trailing edge of the paper 6 is fed while contacting the lower surface of the heating element 1 even when the paper 6 is being conveyed until it comes off the sheet 3 and passes through the downstream rollers 4 and 5. Of these, if the upper rollers 4 are arranged on the downstream side or the lower rollers 5 are arranged on the upstream side and the rollers 4 and 5 are arranged, it is apparent that the same action and effect can be obtained.

As described above, heat is applied to the paper 6 from the heating element 1, and the print medium such as the solid ink on the paper 6 is melted and fixed, and then the paper 6 is used by the paper discharge rollers 16 and 17. The paper is discharged onto the paper receiver 18.

[0015]

[Effect of device]

 As is apparent from the above description, the heat fixing device of the present invention has the following effects. That is, by changing the arrangement of the rollers installed upstream and downstream of the heating element, the paper can be reliably brought into contact with the heating element, so that the entire surface of the sheet can be fixed sufficiently. Become. Moreover, compared with the conventional device, the structure is not complicated, the manufacturing cost is not changed, and the conventional device can be easily changed to the device of the present invention.

[Brief description of drawings]

FIG. 1 is a front view, partly in cross section, schematically showing the structure of a printing apparatus including a heat fixing device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a device of the present invention in which a part of the heat fixing device in FIG. 1 is enlarged.

FIG. 3 is a perspective view illustrating a structure of a conventional general heat fixing device.

FIG. 4 is a cross-sectional view showing a part of the heat fixing device of FIG.

5 is a cross-sectional view showing a part of the heat fixing device in FIG. 3, showing a state in which a sheet reaches a downstream roller.

[Explanation of symbols]

 1 Heating Element 2, 3, 4, 5 Conveying Roller 6 Paper 7 Paper Guide 8 Print Head 9 Paper Feed Roller 10, 14 Guide on Paper Path 11 Platen 16, 17 Paper Ejection Roller 18 Paper Receiver 19 Cover 20 Paper Feed Cassette

Claims (1)

[Scope of utility model registration request] 1. A heating element for fixing a print medium on a sheet, a first sheet conveying unit arranged upstream of the heating element for feeding a sheet to the heating element, and arranged downstream of the heating element. And a second paper transporting means for feeding the paper from the heating element to a speed slightly higher than the paper feeding speed by the first paper transporting means, and the first paper transporting means is sent by the same transporting means. A thermal fixing device, characterized in that a leading end portion of a sheet is configured to come into contact with the heating element.