JPH0934307A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut off the heat from a heating body instantaneously when the conveyance of a recording form stops and prevent the recording form from being turned yellow or ignition by shielding the recording form from a heat-ray radiation body by a heat-ray shielding body. SOLUTION: The recording paper 40 while passing in the fixing device 5 is fixed with the radiant heat of the heating body 52 as the heat-ray radiation body without contacting. A semicircular reflection body 53 rotates around an axis of rotation nearly centering on the heating body 52. The external surface of the semicircular reflection body 53 is formed of a heat insulating material. When the fixation is not carried out, semicircular reflection body 53 itself acts as a heat-ray shield body. When the recording paper 40 is finished or interrupted, or owing to some trouble, when the conveyance is stopped, the supply of the electric power to the heating body 52 is stopped and at the same time, the semicircular reflection body 53 rotates around the axis of rotation to instantaneously shield the recording paper 40 from the heating body 52,thereby preventing the recording paper 40 from being turned yellow or ignition owing to the heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fixing a toner image formed on a recording sheet onto the recording sheet.

[0002]

2. Description of the Related Art The main fixing technique in the conventionally known electrophotographic technique includes a so-called contact type using a heating roller and a heating belt and a so-called non-contact type using a heating wire or a lamp. The non-contact type has an advantage that it can be fixed to thin recording paper without causing deformation of the recording paper.

[0003]

However, in the case of fixing at a high speed, the heating element of the fixing device becomes higher in temperature. Therefore, even if the supply of the current to the heating element is stopped when the recording paper is stopped. There is a problem in that the recording paper is burnt by heat and turns yellow or ignites.

In view of the above circumstances, an object of the present invention is to perform recording in a non-contact type fixing device used in an electrophotographic apparatus by instantaneously shielding heat from a heating element when the conveyance of recording paper is stopped. It is to provide a method for preventing yellowing and ignition of paper.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a heat-radiation type fixing device in which a heat-radiation which faces a recording sheet on which a toner image is attached and conveyed. A body and a blocking means for blocking between the recording sheet and the heat ray radiator by a heat ray shield are provided.

[0006]

According to the present invention, when the recording paper is stopped to be conveyed, the heat from the heating element can be instantaneously shut off to prevent the recording paper from being ignited.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 9 shows a basic configuration of a printer that forms a color image on both sides of a recording sheet as an example of an electrophotographic apparatus to which the present invention is applied. The first color printing set 1 and the second color printing set 2 each have four printing stations, namely a first cyan printing station 11 and a first cyan printing station 11.
Magenta printing station 12, first yellow printing station 13, first black printing station 14
And a second cyan printing station 21, a second magenta printing station 22, a second yellow printing station 23, and a second black printing station 24.

As shown in FIG. 10, the basic construction of each printing station is a recording medium 31 and a charger 32, an optical system 33, a developing device 34, a transfer device 35, a static eliminator 36, and an eraser 37 arranged around the recording medium 31. , Cleaner 38. The developing machine 34 contains toner 340 for recording. FIG.
The printing principle at each printing station will be described using.
The recording body 31 made of an organic photoconductor negatively charged by the charger 32 rotates in the clockwise direction, and a laser beam 39 emitted from the optical system 33 forms a negative electrostatic latent image, and then conveys it to the developing section. Be done. This electrostatic latent image is developed by the negatively charged toner 340 of the developing device 34 to form a toner image on the surface of the recording body 31. This is electrostatically transferred onto the recording paper 40 by the positive corona discharge of the transfer device 35. The residual charge on the surface of the recording body 31 is eliminated by the eraser 37,
The residual toner is removed by the cleaner 38. The recording sheet 40 after the transfer is destaticized by the destaticizer 36 and sent to the next printing station.

For simplification, FIG. 9 shows only the recording body 31 and the transfer unit 35 in each printing station. Cyan toner is used in the first and second cyan printing stations, magenta toner is used in the magenta printing station, yellow toner is used in the yellow printing station, and black toner is used in the black printing station. The recording bodies that make up the first color printing set 1 rotate clockwise, and the first recording paper 100, which is a continuous paper pulled out from the first paper supply unit 150, is a member of each of the first color printing sets 1. The color toner images are conveyed from right to left by the first recording sheet conveying means 3 along the printing station, and the color toner images formed on the recording medium are sequentially superimposed and transferred.
A color image is formed on the front surface (upper surface) of the recording paper 100. On the other hand, the recording medium that constitutes the second color printing set 2 rotates counterclockwise, and the second paper feeding means 250
The second recording paper 200 pulled out from the second color printing set 2 is transported from the right to the left by the second recording paper transporting means 4 along each printing station of the second color printing set 2, and in the second color printing set 2. The color toner images formed on the recording medium are sequentially transferred in an overlapping manner to form a color image on the back surface (lower surface) of the second recording paper 200. The first recording paper 100 on the surface of which the color image is formed is fixed by the non-contact fixing device 5, cut into a predetermined size by the cutter 44, and stored in the first stacker 152.
Similarly, the second recording sheet 200 having the color image formed on the back side is fixed by the fixing device 5 and then the cutter 44.
Are cut into a predetermined size and stored in the second stacker 252.

When double-sided printing is performed on continuous recording paper by the color electrophotographic apparatus of this structure, the first recording paper 100 is used.
The first color printing set 1 is used to form a color image on the surface (upper surface) of the first recording paper 100, and then the fixing device 5 fixes the color image. Moving from the left to the right to enter the second recording paper conveying means 4, and the second color printing set 2 forms a color image on the back surface (lower surface) of the first recording paper 100. After that, the toner is fixed by the fixing device 5 and stored in the second stacker 252.

Next, an embodiment of the present invention will be described with reference to the drawings. In the following figures, (a) shows the case where the recording sheet 40 is being conveyed at a specified speed during fixing, and (b) shows the case where the recording sheet 40 has stopped during non-fixing or the conveying speed has become below the specified speed. The state when the fixing operation is stopped is shown. FIG. 1 shows a first embodiment of the present invention.
In FIG. 1A, a toner image is formed on the surface (left side surface) of the recording paper 40, which is continuous paper, and is conveyed in the direction of the arrow by two sets of rollers 51 and passes through the fixing device 5. At times, it is fixed in a non-contact manner by the radiant heat of the heating element 52 which is a heat ray radiator. The two heating elements 52 are the recording paper 4
It is installed parallel to 0 and perpendicular to the transport direction of the recording paper 40. As the heating element 52, a light emitting type such as an infrared lamp or a resistance heating type such as a heating wire is used. The semi-circular reflector 53 has a structure that rotates around a rotation axis with the heating element 52 as the approximate center. The outer surface of the semicircular reflector 53 is made of a heat insulating material. When the recording paper 40 is being conveyed at the specified speed, the toner image on the surface of the recording paper 40 is heated by the heating element 52 in the energized state and fixed on the recording paper 40. On the other hand, when the recording paper 40 is stopped from being conveyed due to the end or interruption of the recording work or some trouble of the apparatus, the power supply to the heating element 52 is stopped, and at the same time, as shown in FIG.
As shown in (b), the semi-circular reflector 53 rotates around the rotation axis to instantly cut off the space between the heating element 52 and the recording paper 40 to prevent the recording paper 40 from yellowing or igniting due to heat. To prevent. That is, at the time of non-fixing, the semicircular reflector 53 itself acts as a heat ray shield.

A second embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment in that the distance between the recording sheet 40 and the heating element 52 is different from g when fixing and G when not fixing. Heating element 52 during fixing
The distance between the recording sheet 40 and the recording sheet 40 is narrowed and the recording sheet 40 is heated efficiently. However, since the distance between the semi-circular reflector 53 and the recording sheet 40 is narrow, the semi-circular reflector 53 rotates as it is when the fixing operation is stopped. When it does, it will hit the recording paper 40. Therefore, in this embodiment, the semicircular reflector 53
The heating element 52 and the semicircular reflector 53 are moved so as to retreat from the recording paper 40 in conjunction with the rotation operation of the recording sheet 40. Although such a linear movement mechanism is simple in operation and many, the pantograph drive mechanism is one of the effective means.

A third embodiment of the present invention will be described with reference to FIG. The feature of this embodiment is that the two fixing devices of the second embodiment are combined to fix two independent recording sheets at the same time. This is effective in the case where the first recording sheet 100 and the second recording sheet 200 are simultaneously fixed in FIG. However, in the case of FIG. 6, when performing double-sided printing, the recording sheet 100 is once placed on the second recording sheet conveying means 4 after fixing one side, but when the fixing device 5 is used, the printing process of FIG. Another method is used, in which a toner image is formed on both sides of a recording sheet and then both sides are fixed at the same time.

A fourth embodiment of the present invention will be described with reference to FIG. The feature of the present embodiment is that either one of the semicircular shields 54 provided outside the semicircular reflector 53, in the present embodiment, the semicircular shield 54 has a rotation axis with the heating element 52 as the approximate center. It is designed to rotate around. Similar to the semi-circular reflector 53, the outer surface of the semi-circular shield 54 is made of a heat insulating material. By rotating the semicircular shield 54 as shown in FIG. 4B, the heating element 52 is completely covered by the semicircular reflector 53 and the semicircular shield 54 during the non-fixing time, and the heat of the heating element 52 is generated. Since it is confined, the temperature rise inside the fixing device 5 is suppressed, and even if the recording paper 40 is in a non-fixed state for a long time, the recording paper 40 is not affected by heat.

A fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment in FIG. 1 in that the semicircular reflector 53 is divided into two. The two-divided circular reflector 55 has a structure that rotates around a rotation axis with the heating element 52 as the approximate center. Figure 5 (b) when unfixed
Like the upper circular reflector 551 of the two-divided circular reflector 55
Rotates clockwise and the lower circular reflector 552 rotates counterclockwise to cut off the space between the heating element 52 and the recording paper 40.
In this embodiment, compared with the rotation angle of 180 degrees of the semicircular reflector 53 of the first embodiment, the rotation angles of the upper circular reflector 551 and the lower circular reflector 552 of the two-divided circular reflector 55 are 90
It has the advantage of being able to cut off at high speed in half and to support high-speed printing.

A sixth embodiment of the present invention will be described with reference to FIG. The present embodiment is different from the first embodiment in FIG. 1 in that a linear reflector 56 having a rotation axis provided so as to sandwich the heating element 52 is used instead of the semicircular reflector 53. is there. A linear reflector 56 is provided around the rotation axis indicated by the black circle c.
The upper linear reflector 561 rotates clockwise and the lower linear reflector 562 rotates counterclockwise to block between the heating element 52 and the recording paper 40. In the present embodiment, the rotation angle of the upper linear reflector 561 and the lower linear reflector 562 is approximately 90 degrees, and the high linear blocking can be achieved at a high speed, which has an advantage that high speed printing can be supported.

A seventh embodiment of the present invention will be described with reference to FIG. In FIG. 7, at the time of non-fixing (b), only the portion of the upper linear reflector 561 and the lower linear reflector 562 near the recording sheet 40 as viewed from the rotation axis rotates, and the portion between the heating element 52 and the recording sheet 40 is rotated. Shut off. Therefore, at the time of non-fixing, the heating element 52 is completely wrapped in the linear reflector 56 and the heat from the heating element 52 is confined, so that the recording paper 40 remains untouched for a long time as in the fourth embodiment shown in FIG. It has an advantage that the recording paper 40 is not affected by heat even in the fixing state.

A concrete example of the method of driving the interruption means in the fixing device of the present invention will be described with reference to FIG. 8 by taking the case of the sixth embodiment shown in FIG. A drive cylinder 57 having a large diameter and coaxial with the rotation shaft is fixed to the rotation shaft indicated by a black circle c. A single thin metal drive wire 58 is wound around each of the drive columns 57 a plurality of times so that they are successively hung as shown in the figure.
One end of the drive line 58 is connected to the spring 59, and the other end is connected to a mechanical switch mechanism (not shown). At the time of fixing (a), the drive line 58 is pulled upward and the spring 5
9 is in a stretched state. At the time of non-fixing (b), the force pulling the drive line 58 upward is released by the switch mechanism and the spring 59 is released.
Pulls the drive line 58 downward, and the drive column 57 rotates, so that the upper linear reflector 561 of the linear reflector 56 rotates clockwise and the lower linear reflector 562 rotates counterclockwise about the rotation axis. It rotates to cut off the space between the heating element 52 and the recording paper 40. This method of driving the breaking means has a simple mechanism and high reliability, and can be applied to all the other embodiments of the fixing device of the present invention.

Various combinations of the interrupting means shown in the respective embodiments of the fixing device of the present invention can be considered. For example, the semicircular shield 54 in the fourth embodiment may be divided like the bisection circular reflector 55 in the fifth embodiment. In addition, the linear reflector 56 according to the sixth embodiment has the shape of the reflector opposite to the recording paper 40 as seen from the heating element 52 like the two-divided circular reflector 55 according to the fifth embodiment. You may make it into a circular shape from a straight line.

[0020]

As described above, according to the present invention, when the conveyance of the recording sheet is stopped, the heat ray shield instantaneously cuts off between the heating element and the recording sheet and the recording sheet becomes yellow due to heat. There is an effect that it is possible to prevent burning and ignition.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a fixing device showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a fixing device showing another embodiment of the present invention.

FIG. 3 is a configuration diagram of a fixing device showing another embodiment of the present invention.

FIG. 4 is a configuration diagram of a fixing device showing another embodiment of the present invention.

FIG. 5 is a configuration diagram of a fixing device showing another embodiment of the present invention.

FIG. 6 is a configuration diagram of a fixing device showing another embodiment of the present invention.

FIG. 7 is a configuration diagram of a fixing device showing another embodiment of the present invention.

FIG. 8 is a configuration diagram of a drive mechanism of a breaking means of the present invention.

FIG. 9 is a configuration diagram of an electrophotographic apparatus to which the present invention is applied.

FIG. 10 is an explanatory diagram of a printing process of the electrophotographic apparatus to which the present invention is applied.

[Explanation of symbols]

5 ... Fixing device, 40 ... Recording paper, 52 ... Heating element, 5
3 ... Semi-circular reflector, 54 ... Semi-circular shield, 55 ... Divided circular reflector, 56 ... Linear reflector

Claims (3)

[Claims] 1. In a heat-radiation-type fixing device, a heat-ray radiator is provided between a recording paper and the heat-ray radiator, the heat-ray radiator facing a recording paper on which a toner image is attached and conveyed. A fixing device having a blocking means for blocking with a shield. 2. The heat ray shield is located on the opposite side of the heat ray radiator from the heat ray radiator, and is rotated around the heat ray radiator to cut off between the heat ray radiator and the heat ray radiator. The fixing device according to claim 1, wherein: 3. The recording sheet and the heat ray radiator by rotating the heat ray shield about a rotation axis provided in front of and behind the heat ray radiator at a substantially equal distance from the heat ray radiator when viewed from the recording sheet. The fixing device according to claim 1, wherein the fixing device and the fixing device are blocked from each other.