JPH0469902B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for fixing toner images formed in image forming apparatuses such as copying machines and facsimile machines. [Technical Background] In image forming apparatuses such as copying machines and facsimile machines, a visible image is formed by fixing a toner image formed by development onto an image support made of paper or the like. As a method for fixing toner images, a heating roller fixing method using a heating roller is conventionally known.
However, this heating roller fixing method requires waiting time at the beginning of image formation until the temperature of the heating roller rises to the temperature required for fixing the toner, and in particular, fixing the toner image on a large area image support. Since this requires a large amount of heat, there is a problem that the standby time is considerably long. [Prior Art] For these reasons, a method has been developed in which a flash lamp is used to fix a toner image by irradiating light energy from the flash lamp. According to such a method, the flash lamp can be turned on instantly, and has the advantage that it can be fixed immediately without requiring any waiting time. Specifically, in a fuser, a flash lamp such as a xenon lamp is housed in a lamp cover that usually has a reflective mirror surface on its inner surface and an opening of the size necessary for fixing, and the opening is covered with a lamp cover. A cover glass is provided. Fixing is carried out by sequentially passing an image support, such as a transfer paper, carrying an unfixed toner image on its surface along the opening surface of the lamp cover. This is done by turning on the flash lamp every time the fixing device moves by the effective fixing width. That is, the light emitted from the flash lamp is reflected either directly or by the reflective mirror surface on the inner surface of the lamp cover, and some of the light hits the toner image on the transfer paper and the other part hits the margin, and the light that hits the toner image on the transfer paper ( In particular, heat rays) are absorbed and heat the toner. On the other hand, the light that hits the margins of the transfer paper other than the toner image is reflected and hits the reflective mirror surface of the lamp cover, where it is reflected again and hits the transfer paper, and the operation is repeated. In this way, most of the light emitted from the flash lamp is absorbed by the toner image as it is repeatedly reflected between the transfer paper and the reflective mirror surface of the lamp cover. As a result, the toner image is molten and liquefied, and then solidified and fixed onto the transfer paper. [Problem to be solved by the invention] In this way, the toner image is fixed, but
Recently, large areas such as 370 mm width in the conveying direction are being developed.
There are cases where it is required to fix a toner image on transfer paper with a width of mm or more, and in this case, a large flash lamp with a length corresponding to the width of the transfer paper is required, and moreover, a large amount of light emission energy is required. shall be. When supplying such a large amount of luminous energy to a flash lamp to light it,
It has been found that since a large amount of energy is suddenly applied to the toner, there is a problem in that the toner tends to scatter or burn, resulting in the generation of dust, smoke, odor, etc. On the other hand, if you make the flash lamp emit light more slowly and emit light for a longer time, the effect of heat dissipation from the toner will increase.
As a result, unfixed toner remains, making it impossible to achieve good fixing. [Object of the Invention] The present invention has been made based on the above-mentioned circumstances, and the object thereof is to use a flash lamp to form a toner image on a large-area image support, and prevent the toner from scattering or scattering due to overheating. To provide a toner fixing method capable of fixing the toner without burning the toner and without leaving unfixed toner due to lack of energy. [Means for Solving the Problems] The toner fixing method of the present invention includes a flash lamp having an arc length of 400 mm or more, a main capacitor, and a supply circuit that supplies charging energy from the main capacitor to the flash lamp. A toner fixing device including a discharge circuit and a trigger circuit for triggering the flash lamp is used, and the damping factor α of the discharge circuit is 1.8 or more.
2.7 or less, and supplying energy of 500 J or more to the flash lamp per one light emission to cause the flash lamp to emit light and fix the toner image on the image support. Features. [Example] The present invention will be described in detail below with reference to the drawings. FIGS. 1A and 1B are explanatory diagrams schematically showing an example of a toner fixing device that can be used in the present invention,
1 is a flash lamp made of, for example, a xenon flash lamp, and its arc length l ₁ is 400
mm or more. This flash lamp 1 has an opening surface 22 with a width L ₁ and a reflecting mirror surface 21 formed on the inner surface.
A transparent cover glass 24 is provided on the opening surface 22 of the lamp cover 23. Although not shown, a trigger wire wound spirally, for example, is disposed on the outer wall surface of the flash lamp 1. 12
1 is a separating and conveying tank for transfer paper, which is a support for a transferred toner image, and 13 is a rear reflecting plate that also serves as the surface of the tank. Further, 14 is a driving roller of the separation conveyance belt 15, 16 is a transmission roller thereof, and 17 is a paper discharge roller. When the transfer paper, on which the toner image has been transferred, is conveyed on the separation conveyance belt 15 in the direction of arrow A, the conveyance switch 18 provided at the inlet of the fixing section of the separation conveyance tank 12 outputs a fixing control signal. Timing detection is performed. When the leading edge of the transfer paper turns on the transport switch 18 and enters the fixing area Q of the effective fixing width L ₂ and effective fixing length L ₂ of the flash lamp 1, the flash lamp 1 emits light once. Energy of 500 J or more is supplied per flash lamp 1 to emit light to fix the toner on the transfer paper. After that, the flash lamp 1 is adjusted to the effective fixing width until the trailing edge of the transfer paper passes through the fixing section.
Light is emitted every time the transfer paper advances a distance of L ₂ ,
Establishment of all areas. In addition, in the figure, 19 is a paper discharge detection switch. FIG. 2 is an explanatory circuit diagram showing an electric circuit portion that causes the flash lamp 1 to emit light. 3 is a charging circuit, which includes a step-up transformer 32, a solid state relay (SSR) 31 inserted between the primary side of the step-up transformer 32 and the AC power supply, and a charge circuit of the step-up transformer 32. Detection by a rectifier 33 connected to the secondary side, voltage dividing resistors 34 and 35 for detecting the charging voltage of the main capacitor 4 for energy supply, which will be described later, and a capacitor charging signal CHG and voltage dividing resistors 34 and 35, which will be described later. The charging voltage control circuit 36 controls the charging voltage of the main capacitor 4 by controlling the opening/closing operation of the solid state relay 31 based on the voltage V ₀ . 37,
38 is a capacitor and inductor for power factor improvement, and 39A and 39B are circuit breakers. In the solid state relay 31, when the signal to the input terminal 31D is low level (L level), the AC side terminals 31A, 31B
During this conduction period, the main capacitor 4 is charged by the power supplied from the AC power source AC.On the other hand, when the signal to the input terminal 31D is high level (H level), the AC side terminal 31A ,3
1B is cut off and the supply of power from the AC power source AC is stopped. 4 is a main capacitor for energy supply, and in this example, four electrolytic capacitors 41, 42, 4
3 and 44 are connected in series, and the terminal 4
A and 4B are connected between the output terminals of the rectifier 33. The charging energy stored in the main capacitor 4 is supplied to the flash lamp 1 to emit light, so in order to supply the flash lamp 1 with energy of 500 J or more per light emission, the main capacitor 4 must be It is necessary to appropriately set the capacity and charging voltage of the battery so that the charging energy is 500 J or more. 5 is a supply circuit for supplying charging energy of the main capacitor 4 to the flash lamp 1;
Anode terminal 1 of flash lamp 1 is connected from positive terminal 4A of main capacitor 4 to air core reactor 51.
The part leading to 0A and the negative terminal 4 of the main capacitor 4
It consists of a portion from B to the cathode terminal 10B of the flash lamp 1. By changing the magnitude of the inductance L of the air-core reactor 51, the value of the damping factor α of the discharge circuit 6, which will be described later, can be set. A discharge circuit 6 is constituted by the main capacitor 4, the supply circuit 5, and the discharge path of the flash lamp 1, and the discharge circuit 6 is closed when the flash lamp 1 emits light. Reference numeral 11 denotes a trigger wire, and this trigger wire 11 is provided, for example, on the outer wall surface of the flash lamp 1 in a spiral manner. 7 is a trigger circuit that triggers the flash lamp 1. The high voltage side output terminal 7D of this trigger circuit 7 is connected to the trigger wire 11, and when the trigger signal TG is input to the input terminal 7B, the flash is output from the output terminal 7D. The high voltage pulse required to trigger the lamp 1 is generated, which is applied to the trigger wire 11 which causes the flash lamp 1 to be triggered.
is triggered. The resistor 81 and the constant voltage element 82 constitute a voltage stabilizing circuit for supplying a driving voltage to the trigger circuit 7. The charging voltage control circuit 36 is basically composed of a comparator 361 and a transistor 362 that controls the start and stop of the operation of the comparator 361, as shown in FIG. The output terminal is connected to the output terminal 36A via a resistor 363, the base of the transistor 362 is connected to the input terminal 36B via a resistor 364, and the non-inverting input terminal of the comparator 361 is connected to the input terminal 36A via a resistor 365.
6C, and its inverting input terminal is connected via a resistor 366 to a reference voltage source composed of resistors 367, 368, and 369. E is a voltage source, 370,
371 and 372 are diodes and capacitors for preventing malfunction, respectively; a capacitor 373, a Zener diode 374, and a resistor 375 are components of a voltage stabilizing circuit. This charging voltage control circuit 3
6, during the period when the capacitor charging signal CHG input to the terminal 36B is at the L level, the transistor 362 is off and the comparator 361 is in the operating state, and the main capacitor 4, which is not being charged at this time, is in the OFF state. Since the detection voltage V ₀ is smaller than the reference voltage Vr, the comparator 36
1 is at the L level, which is supplied to the input terminal 31D of the solid state relay 31.
A and 31B are electrically connected, and charging of the main capacitor 4 by the charging circuit 3 is started. With this charging,
When the charging voltage of the main capacitor 4 reaches the set voltage V ₁ necessary for fixing the toner, the detection voltage V ₀ becomes the reference voltage Vr.
When the output of the comparator 361 is inverted and becomes the H level, the signal to the input terminal 31D of the solid state relay 31 becomes the H level, and the signal to the input terminal 31D of the solid state relay 31 becomes the H level.
A and 31B are cut off, and the charging operation of the main capacitor 4 by the charging circuit 3 is stopped. One terminal 36
During the period when the capacitor charging signal CHG input to B is at H level, the transistor 362 is on, and at this time the operation of the comparator 361 is stopped, and its output becomes H level regardless of the magnitude of the detection voltage _V0 . As a result, the terminals 31A and 31B of the solid state relay 31 are cut off, and the charging operation by the charging circuit 3 is stopped. The trigger circuit 7 is basically composed of a charging/discharging capacitor 71, a high voltage pulse transformer 72, and a thyristor 73 which is a switching element, as shown in FIG.
During the operation period of charging circuit 3, terminals 7A and 7C
The capacitor 71
is charged, and then the trigger signal TG is sent to terminal 7B.
When applied to the gate of the thyristor 73 from
On the next side, a high voltage pulse of, for example, 10 to 20 KV is generated, which is applied to the trigger wire 11 and the flash lamp 1 starts emitting light. 74 and 75 are protection diodes, 76 is a constant voltage element for overvoltage prevention, and 77 is a charging resistor. In the electric circuit configured as described above, the damping factor α of the discharge circuit 6 is set to a value of 1.8 or more and 2.7 or less. In the discharge circuit 6, when the flash lamp 1 emits light and the circuit is closed, the discharge circuit 6 equivalently has a capacitance C of the main capacitor 4, an inductance L of the air core reactor 51, and a load resistance R due to the flash lamp 1. (However, it is a function of the lamp voltage.) Since it is a series circuit, the damping factor α of this discharge circuit 6 can be expressed as α=Ko/(VoZo) ^1/2 . However, Vo is the initial potential before the main capacitor 4 starts discharging, and Zo is

[Experiment example]

We conducted an experiment to actually fix toner images by setting various values of the damping factor α of the discharge circuit 6 under the following conditions. I investigated whether it was good or bad. The results are shown in Table 1. Arc length of the flash lamp: 510mm Effective fixing length: 457mm Transfer paper: Input energy of the flash lamp for one light emission while transporting A2 size plain paper in the longitudinal direction: 550J

〔Effect of the invention〕

As described above in detail, the present invention includes a flash lamp having an arc length of 400 mm or more, a discharge circuit including a main capacitor and a supply circuit that supplies charging energy from the main capacitor to the flash lamp, and Using a toner fixing device equipped with a trigger circuit that triggers a flash lamp, the damping factor α of the discharge circuit is
Set the value to be 1.8 or more and 2.7 or less, and set the value to be 1.8 or more and 2.7 or less, and
This toner fixing method is characterized by supplying energy of 500 J or more to cause the flash lamp to emit light to fix the toner image on the image support. A toner image can be fixed on a body without causing toner scattering or toner burning due to overheating, and without leaving unfixed toner due to lack of energy.

[Brief explanation of the drawing]

FIGS. 1A and 1B are an explanatory vertical front view and a vertical side view schematically showing an example of a toner fixing device that can be used in the present invention, and FIG. 2 is an explanatory view showing an electric circuit portion that makes a flash lamp emit light. Figure 3 is an explanatory circuit diagram showing an example of a charging voltage control circuit, Figure 4 is an explanatory circuit diagram showing an example of a trigger circuit, and Figure 5 is an explanatory circuit diagram showing an example of a trigger circuit. FIG. 3 is a diagram showing a relationship with a current waveform. 1... Flash lamp, 21... Reflective mirror surface, 22
...Opening surface, 23...Lamp cover, 24...Cover glass, 15...Separation conveyance belt, 18...Conveyance switch, 19...Sheet discharge detection switch, 3...Charging circuit,
31... Solid state relay, 34, 35... Voltage dividing resistor, 4... Main capacitor, 36... Charging voltage control circuit, 5... Supply circuit, 6... Discharging circuit, 11... Trigger wire, 7... Trigger circuit, 361... Comparator, 362...Transistor, 71...Charging/discharging capacitor, 72...High voltage pulse transformer, 73...Thyristor.

Claims (1)

[Claims] 1. A flash lamp having an arc length of 400 mm or more, a discharge circuit including a main capacitor and a supply circuit that supplies charging energy from the main capacitor to the flash lamp, and a trigger circuit that triggers the flash lamp. using a toner fixing device, the damping factor α of the discharge circuit is set to a value of 1.8 or more and 2.7 or less, and 500 J or more of energy is supplied to the flash lamp per one light emission. A toner fixing method characterized in that a toner image is fixed on an image support by causing the flash lamp to emit light.