JPS6330629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device used in copying machines, laser printers, and the like.

Conventionally, this type of fixing device includes a fixing device using a flashing lamp, a roll fixing device, and a radiant heat fixing device. In a fixing device that uses flash lamps, two flash lamps are used as shown in Figure 1.
L ₁ and L ₂ are made to emit light at the same time, and this flash lamp L ₁ ,
Flashing light of _L2 is applied to the recording paper P for fixing. In this case, as shown in FIGS. 2 and 3, the output of AC power source S ₁ is boosted by transformer T ₁ and applied to capacitors C ₁ and C ₂ through diodes D ₁ and D ₂ , respectively. Then, the charging pressure of the capacitors C ₁ and C ₂ is applied to the flashing lamps L ₁ and L ₂ respectively,
These flashing lamps L ₁ and L ₂ are simultaneously triggered and emitted in synchronization with the recording paper P by a trigger circuit (not shown). Further, when the recording paper P is conveyed over a distance corresponding to the length l in 2 seconds, for example, the flashing lamps L ₁ and L ₂ are configured to emit flash light for 2 seconds.

Furthermore, in order to reduce the rush current, it is also possible to alternately charge the capacitors C ₁ and C ₂ as shown in FIG. 4.

Charging of the capacitors C ₁ and C ₂ is started when a switch (not shown) is closed in response to a recording operation start signal.

However, such fusing devices usually use capacitors.
When C ₁ and C ₂ are charged, the terminal voltage becomes a high voltage of several hundred volts, and it takes 3 to 5 seconds from the start of recording operation until the recording paper P reaches the fixing position in a normal copying machine. Therefore, while maintaining the high voltage of capacitors C ₁ and C ₂ for this long time, leakage current flows and power is wasted, shortening the life of capacitors C ₁ and C ₂ . do. Also, the flashing lamps L ₁ and L ₂ may be triggered by electrostatic nozzles generated from high voltage parts, relays, etc. of the copying machine, resulting in abnormal flashes. Also, capacitor C ₁ ,
There is a high risk of electric shock when a person touches the charging-related parts of C ₂ . Furthermore, if the recording paper P jams between the paper feed section and the fixing position, the capacitor C ₁ ,
This results in unnecessary charging and discharging of _C2 .

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that eliminates the above drawbacks, saves power, extends the life of the capacitor, prevents abnormal flashes, and prevents wasteful charging and discharging of the capacitor.

In a fixing device that performs fixing by applying each charging voltage of a plurality of capacitors to a plurality of flash light sources and applying the flash light of the plurality of flash light sources to a recording paper, The apparatus includes a plurality of detection means provided to detect the recording paper, and a means for starting charging of the plurality of capacitors in response to each detection signal from the plurality of detection means.

Embodiments of the present invention will be described below with reference to the drawings.

In the fixing section of a copying machine (or printer, etc.), two flashing lamps L ₃ and L ₄ are installed above the path of the recording paper P along the traveling direction of the recording paper P, as shown in FIGS. 5 and 6. juxtaposed each flashlamp L ₃ ,
L ₄ has reflectors M ₁ and M ₂ arranged on the sides and rear, and provides flash light to an area roughly dividing the recording paper P into two in the front and back of the path of the recording paper P. ing.

Now, when the recording paper P knocks down the micro switch MS ₁ , the switch S ₁ is turned on and the capacitor C ₃ is charged. Then, when the recording paper advances by l, switch MS ₃ is activated. Switches MS ₃ and MS ₂ operate almost simultaneously, and capacitor C ₄ starts charging by switches MS ₂ and S ₂ . Capacitor _C4 is then charged until switch _MS4 is activated. After that, the same operation is repeated even if the recording paper is continuously fed. However, here it is necessary to leave some space between the recording sheets for the flashing time. Further MS ₃ and MS ₄
Since it is only necessary to activate the trigger circuit, it is preferable that the circuit be turned off after sending the pulse signal. Also, switches S ₁ and S ₂ were placed on the high pressure side.
When charging capacitors C ₃ and C ₄ individually using the AC power source as a separate power source, switches S ₁ and S ₂ can be inserted on the AC side. The length of the recording paper P in the advancing direction is l
Then, when the 1/2 length front side of the recording paper P enters the flashlight irradiation range of the flashlight lamp _L3 , the micro switch _MS3 detects the leading edge of the recording paper P, and the trigger circuit starts flashing. Trigger lamp L ₃ ,
Flashing light from the flashing lamp _L3 is applied to the front side of the recording paper P, and the toner image is fixed. Next, when the 1/2 length rear portion of the recording paper P enters the flashlight irradiation range of the flashlight lamp L ₄ , the micro switch MS ₄ detects the leading edge of the recording paper P and the trigger circuit starts flashing. Trigger lamp L ₄ ,
Flashing light is applied from this flashing lamp _L4 to the rear side of the recording paper P, and the toner image is fixed. Here, the flashing occurs for less than 1 second, and its peak width is generally about 1/10 to 1/100,000 seconds. Further, as shown in FIGS. 6 and 7, the output of the AC power source S ₂ is boosted by a transformer T ₂ , rectified by diodes D ₃ and D ₄ , and applied to capacitors C ₃ and C _4, respectively. The charging voltages of the capacitors C ₃ and C ₄ are then applied to the flash lamps L ₃ and L ₄ respectively, and the switch is activated.
By turning on S ₃ and S ₄ in conjunction with micro switches MS ₃ and MS ₄ , respectively, flash lamps L ₃ and
L ₄ is triggered by trigger circuits TR ₁ and TR ₂ , respectively, to emit light. In addition, micro switch MS ₁ ,
Instead of MS ₂ , MS ₃ , and MS ₄ , a photo cell, a Cds cell, a detection means based on a change in capacitance, etc. may be used.

By causing the flashing lamps L ₃ and L ₄ to emit light alternately in this manner, the capacitors C ₃ and C ₄ can be charged alternately, and the combined charging current can be reduced. Therefore, the lash current can be reduced and made uniform, reducing noise to other devices and reducing the load on the DC power supply. Furthermore, flash lamps L ₃ , L ₄
In order to emit light alternately, the charged amounts of capacitors C ₃ and C ₄ can be made equal, and good fixing characteristics can be obtained.

FIG. 8 shows the flash lamp L ₃ ,
This shows the capacitor charging current when the light emitting time of L ₄ is shortened to 1/2 and the transport speed of the recording paper P is doubled, but it is possible to further increase the transport speed of the recording paper P to increase the fixing speed. and also the capacitor C ₃ ,
The peaks of each C ₄ charging current never overlap.

In the above embodiment, two flash lamps L ₃ and L ₄ were used, but as shown in FIG. 9, three reflectors M ₃ were used.
Flashing lamps L ₅ to _{L 7} with ~M ₅ are used to emit light in sequence, and the recording paper P is divided into three parts in the direction of travel, and each of the flashing lamps L ₅ to _{L 7} is applied to each part P ₁ to _{P 3} . Fixation can also be performed by applying light to each. In this case, as shown in FIG _. 10, the three capacitors C ₅ to C ₇ are charged with a DC power source, and the respective charging voltages are applied to the flashing lamps L ₅ to _{L 8} respectively. ₇ can be triggered sequentially in synchronization with the recording paper P using a trigger circuit. In this way, it is possible to further increase the speed. Also, as shown in FIG. 11, there is a flash lamp _L8 with four reflectors _M6 to _M9 .
~ _L11 to _{sequentially emit light, divide the recording paper P into four in the direction of travel, and perform fixing by applying flashlight from flashlight lamps L8 to L11} to each of the sections P1 to _P4 , respectively. Similarly, fixing may be performed using five or more flashing lamps.

In addition, in each of the above fixing methods, one flash lamp Li has three or more electrodes as shown in FIG.
ER ₁ to _{ER 3} may be provided to divide the light source into two or more flashing light sources, and the charging voltage of the capacitors Ci ₁ and Ci ₂ may be applied to these, respectively. Each of the capacitors Ci ₁ and Ci ₂ can be charged with one DC power supply, but may be charged with each of the DC power supplies E ₁ and E ₂ respectively. 1st
3 and 14 show an example in which the flashing lamps L ₃ and L ₄ are each divided into two parts in the fixing device shown in FIG. 5, and their charging currents. FIG. 15 is for preventing overlapping of capacitor charging rises during charging as shown in FIG. 14, and FIGS. 16 and 17 illustrate the charging method. micro switch
In MS ₅ , MS ₆ , and MS ₇ , the dotted line portions indicate the state in which the recording paper P is turned over. First, Micro Switch MS ₅
falls down and capacitor C ₃₁ is charged, then when micro switch MS ₆ falls down, capacitor C ₃₁ is de-charged and capacitor C ₃₂ starts charging, then micro switch MS ₇ falls down and capacitor C ₃₂
charging will be stopped. Although not shown, capacitors C ₄₁ and C ₄₂ are similarly charged.

FIG. 18 shows an example suitable for cases where the width of the recording paper is wide or when it is desired to downsize the flash lamp and lower its discharge voltage. In this example, the capacitor is the 14th
It is charged as shown in Figure 17, and the flashing lamp lights up.
Light is emitted in the order of L ₃₁ , L ₃₂ , L ₄₁ , and L ₄₂ . Furthermore, the first
As shown in FIG. 9, it is also possible to align the longitudinal direction of the flashing lamps L ₃ and L ₄ substantially with the traveling direction of the recording paper P.

Further, FIG. 20 is an example of a divided flash, in which one recording paper P is irradiated 1/4 at a time. FIG. 21 shows the relationship between charging and flashing of the capacitor in this example. However, in this case capacitor C ₃ and
There is a difference in charging time for C ₄ . This will almost disappear if the charging time is sufficient, but it will occur if the charging speed is increased, so if the charging time of capacitors C ₃ and C ₄ is made the same, the result will be as shown in Fig. 22. In this case, it is sufficient to start charging the capacitor _C3 earlier by 1/4 sec. If you want to further increase the amount of charge, you will have to start charging earlier, but this will interfere with continuous paper feeding, but in general copiers there is a gap between copies for the optical system to return, so there is no problem. There is no problem. If you still do not want to leave a gap between the sheets, you can solve this problem by having multiple capacitors as shown below. That is, each flashing lamp is provided with a capacitor, but as shown in FIG. 23, one flashing lamp Lx may be provided with a plurality of capacitors Cx ₁ and Cx ₂ and used selectively by the switch SW.

In the embodiment shown in FIG. 5 above, the flash lamp L ₃ ,
Capacitor C ₃ with xenon lamp as L ₄ ,
Set the terminal voltage of _C4 to about 700V and turn on the flash lamp.
When flashing light was applied to a sheet of recording paper for a total of 4 seconds, once for 2 seconds each at L ₃ and L ₄ , it was possible to continuously obtain 15 copies per minute. When fixing was carried out in the same manner by doubling the fixing speed and using a toner with a melting point about 30° C. lower, 30 good copies were obtained per minute.

As described above, according to the present invention, in a fixing device that performs fixing by applying each charging voltage of a plurality of capacitors to a plurality of flashing light sources and applying flashlight from the plurality of flashing light sources to a recording paper, The present invention includes a plurality of detection means provided at different positions near the fixing device to detect the recording paper, and a means for starting charging of the plurality of capacitors in response to each detection signal from the plurality of detection means. The high voltage of the capacitor is no longer maintained for a long time, the leakage current of the capacitor is almost eliminated, power can be saved, and the life of the capacitor can be extended. It is possible to eliminate the risk of abnormal flashing, electric shock to the charging-related parts of the capacitor, and wasteful charging and discharging of the capacitor when the recording paper jams between the paper feed section and the detection means near the fixing device.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a conventional fixing device, Fig. 2 is a circuit diagram showing an electric circuit in the same device, Fig. 3 is a timing chart of the electric circuit, and Fig. 4 is for explaining the conventional fixing method. FIG. 5 is a front view showing a fixing device according to an embodiment of the present invention, and FIG.
The figure is a circuit diagram showing the electric circuit in the fixing device.
7 and 8 are timing charts of the same electric circuit, and FIGS. 9 to 23 are diagrams for explaining other embodiments of the present invention. L ₃ ~ L ₁₁ , Li, Lx...Flash lamp, M ₁ ~ _{M 9} ...
Reflector, P... Recording paper, MS ₁ , MS ₂ ... Micro switch, S ₂ ... DC power supply, T ₂ ... Transformer, D ₃ , D ₄ ...
Diode, _S1 , _S2 ...Switch, _TR1 , _TR2 ...Trigger circuit, _C3 , _C4 ...Capacitor.

Claims (1)

[Claims] 1. In a fixing device that performs fixing by applying each charging voltage of a plurality of capacitors to a plurality of flashlight sources and applying the flashlight of the plurality of flashlight sources to recording paper, different positions near the fixing device are used. A fixing device comprising: a plurality of detection means for detecting the recording paper; and means for starting charging of the plurality of capacitors in response to detection signals from the plurality of detection means.