JPS6365940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device for a copying machine or the like for fixing a toner image into a stable image by heating.

A toner image formed by adhering toner to an electrostatic latent image cannot be put to practical use as a recorded image because the toner particles tend to peel off in that state. For this purpose, a fixing process has been conventionally performed to form a stable visible image, and heat treatment is one method for this fixing process.

In this heat fixing method, a heat source is placed inside a hollow cylinder, a heat-resistant heating element coated on the cylinder surface is heated from the cylinder by heat conduction, and the copy paper is placed between transfer rollers placed opposite to this cylinder. The unfixed toner image is fixed by passing through it.

However, in such conventional fixing devices, an air layer exists between the heat source and the cylinder, resulting in poor heat conduction efficiency.

Particularly when starting up after power is turned on, the structure is such that the hollow cylinder is first heated by radiant heat from the heat source, and then the heat-resistant heating element on the surface of the cylinder is heated by the conductive heat of the cylinder, so the start-up time is long. There is.

In view of these points, the present invention provides a fixing device that has a short startup time after power is turned on, and one embodiment will be described below.

In FIG. 1, 1 is a drum having a photoreceptor on its surface and placed approximately in the center of the apparatus, 2 is a charging corotron that uniformly charges the surface of the photoreceptor, and 3
is an optical means for exposing an original image to the photoreceptor to form an electrostatic latent image of the original image. The short focal length lens array 6 is provided on the top of the drum 1 and is comprised of a focusing light conductor in which a large number of rod-shaped lenses that continuously change in direction are closely arranged. 7 is a developing means for developing the electrostatic latent image formed on the photoreceptor into a visible image using toner 8, and the developing means 7 is, for example, a non-magnetic sleeve 9 containing a large number of fixed magnets fixed on the outer periphery of the sleeve 9. It consists of a magnetic brush developing device that holds toner 8 directly or indirectly by the magnetic force of a magnet and supplies the toner 8 to a photoreceptor while rotating. This developing means 7 is provided on the side of the drum 1. Reference numeral 10 shows the original image visualized by toner 8 on copy paper 11.
Copying paper 11 is supplied substantially horizontally to this transfer corotron 10 from a paper feeding means 12 provided at the bottom right portion of the drum 1. 13 is a heat fixing means, and conveyor belt 1
4, a heat generating section 15, and a pressure roller 16 for pressing the copy paper 11 against the heat generating section 15. The details of the heat fixing means 13 will be described later. Reference numeral 17 denotes a paper ejecting means for ejecting the copy paper 11 to which the original image has been fixed to the outside.
The copy paper 11 moves approximately horizontally from transfer to heat fixing to paper ejection. Returning again to the outer periphery of the drum 1, reference numeral 18 denotes a cleaning means that is provided at a location symmetrical to the developing means 7 on the side of the drum 1 and removes residual toner remaining on the photoreceptor after transfer. It is composed of a blade 19 and the like that scrapes the surface of the photoreceptor to remove residual toner. Reference numeral 20 denotes a static eliminating corotron which discharges a corona having a polarity opposite to that of the charged corotron 2 to eliminate residual charges on the photoreceptor. Reference numeral 21 denotes a drive motor provided at a location remote from the drum 1, and the rotational force of the motor 21 is applied to the drum 1 via an electromagnetic clutch 22.
Furthermore, this drive motor 21 is connected to a chain, etc. in order to drive mechanical drive means such as at least the paper ejection means 17 and the conveyor belt 14 of the heat fixing means 13 located nearby.
They are linked via drive force transmission system parts such as gears. Reference numeral 23 denotes a document table on which a document to be copied is placed and which moves back and forth in the left-right direction relative to the optical means 3 having a slit-like opening. is driven by. A sub-drive motor 24 is provided symmetrically with respect to the drive motor 21 and the drum 1, and the sub-drive motor 24 controls the driving of the sleeve 9 of the developing means 7, the paper feeding means 12, etc. located nearby. . Although not shown, control circuit means for electrically controlling the power supply circuit such as a step-up transformer, the drive motor 21, the optical means 3, the charging and neutralizing corotrons 2, 20, etc. are appropriately arranged in the empty space of the apparatus. There is.

According to this structure, the charging corotron 2 is provided approximately at the top along the outer periphery of the drum 1 in the rotational direction,
A developing means 7, a transfer corotron 10, and a cleaning means 18 are sequentially arranged at positions shifted by about 90 degrees with respect to the optical means 3 arranged on the top near the optical means 3. The path along which the copy paper 11 moves from paper feed to paper ejection is also installed approximately horizontally at the bottom of the drum 1, and the drive motor 21 and sub-drive motor 24 are provided symmetrically with respect to the drum 1. There is.

FIG. 2 shows a part of the control circuit means, 25 is a rectifier for rectifying AC power, 26 is a smoothing circuit consisting of a capacitor and a choke coil, 27 is an inverter, and a switching element 28 consisting of a thyristor etc. 28 and an oscillation circuit 29 for supplying an ignition current to the ignition circuit 28. 3
0 is a step-up transformer, which has a primary winding 31, a transformer core 32, and a corotron step-up winding 33. 34 is a high-voltage circuit for charging, neutralizing, and transferring;
It consists of the winding 33 and lead wires 35, 36, and 37 connected to the winding 33. The lead wire 35 is connected to the electrode of the charging corotron 2 through a diode oriented in one direction and supplies a potential of approximately +6.3 KV, and the lead wire 36 is connected to the electrode of the transfer corotron 10 through a diode oriented in one direction. The lead wire 37 is connected to the electrode and supplies a potential of approximately +6.3 KV, and the lead wire 37 supplies a potential of -5.3 KV to the static eliminating corotron 20 via a diode oriented in the other direction.

The heat generating section 15 of the heat fixing means 13 is constructed as shown in FIG. The core 32 of the step-up transformer 30 is formed in a square shape. A primary winding 31 is wound around the primary side 32a of this □-shaped core 32. Furthermore, this primary winding 31 is covered with an insulating material 38. On the other hand, a corotron boost winding 33 is wound around the secondary side 32b of the square core 32. This boost winding 33 is covered with an insulating material 39. A part of the magnetic flux generated in the primary winding 31 passes through the core 32, but the remaining lines of magnetic force leak from the core 32 and pass through the space, so that an alternating magnetic field is generated in the space near the transformer 30. 40,
Magnetic plates 41 and 42 are placed in the alternating magnetic field and are made of iron, stainless steel, or the like. Since the magnetic plates 40, 41, and 42 are placed in an alternating magnetic field, eddy currents flow inside the magnetic plates and generate heat due to metal resistance. In addition, in this way, the magnetic plates 40, 4
The principle by which 1 and 42 generate heat is generally referred to as the principle of electromagnetic induction heating. Further, as shown in FIG. 1, a material 43 having good thermal conductivity is attached to the heating magnetic plates 40, 41, and 42 by welding or the like. Therefore, the heat of the heat generating magnetic plates 40, 41, 42 is directly transferred to the material 43 having good heat conduction. This heat fixing means 13 is made of a material 43 with good heat conduction.
The temperature value is approximately 120℃. The heat generating section 15 is composed of a step-up transformer 30, magnetic plates 40, 41, and 42, and a material 43 with good heat conduction. In the above embodiment, the copy paper 11 is heated through the material 43 with good thermal conductivity.
Magnetic plates 40, 4 without using the material 43
1 and 42 may be brought into direct contact with the copy paper 11.
If the magnetic plates 40, 41, and 42 are suitably shaped and brought into direct contact with the copy paper 11, the temperature rise characteristics of the heat fixing means 13 can be further improved.

This invention is constructed as described above, and since the copy paper is pressed against the magnetic material heated by electromagnetic induction using a pressure roller, the heat of the magnetic material is directly transmitted to the material with good thermal conductivity without passing through an air layer. The start-up time of the fixing device can be shortened, and electromagnetic induction heating has higher thermal efficiency than conventional radiant heating, so power consumption can be reduced.

In addition, a magnetic material is electromagnetically coupled to a step-up transformer for generating high voltage for the corotron, and an eddy current is induced in the magnetic material to generate resistance heat. Since the toner image is fixed, fixing and heating can be performed simply by providing a magnetic material without providing a dedicated heating device, and the cost of the device can therefore be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of an embodiment of the present invention;
FIG. 2 is a schematic power supply circuit diagram of the same embodiment, and FIG. 3 is a perspective view of essential parts of the same embodiment. 2, 10, 20... Corotron, 11... Copy paper,
16...Pressure roller, 30...Step-up transformer, 4
0, 41, 42...Magnetic material, 43...Material with good heat conduction.

Claims (1)

[Claims] 1 An electrostatic latent image is formed on an image carrier charged by a corotron, and after this electrostatic latent image is developed with toner, it is transferred to transfer paper, and a high voltage for the corotron is generated. A magnetic material is electromagnetically coupled to a step-up transformer for the transfer, eddy current is induced in the magnetic material to generate resistance heat, and the toner image on the transfer paper is fixed by the resistance heat. Features a fixing device.