JPS58102969A - Flash fixation device - Google Patents

Abstract

PURPOSE:To eliminate the fixation variance and at the same time to save energy, by measuring the transferred distance of a recording medium at every time when a flash discharge tube is actuated and charging supplementarily when the difference between the distance corresponding to the fixation width and the measured distance reaches the prescribed value. CONSTITUTION:When the charge starting signal is supplied to a control circuit 6, a high voltage generating circuit 1 is driven to charge a capacitor 2. The charged voltage is detected by a voltage divider 5, and the charging is stopped when the charged voltage reaches the prescribed value. The light emission timing signal is supplied after the charging is over, and a high voltage pulse generating circuit 4 is driven to actuate a flash discharge tube 3. On the other hand, driving pulses the pulse motor are counted by the circuit 6 to measure the transferred distance of a recording medium at every time when the tube 3 is actuated. Then the capacitor 2 is charged supplementarily when the difference between the measured distance and the distance corresponding to the fixation width coincides with the distance equivalent to the time to charge capacitor 2 supplementarily. In such a way, the capacitor 2 is always charged to a high voltage when the flash discharging is carried out to eliminate the variance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash fixing device that is installed in an image recording device such as a facsimile machine and fixes a toner image on a recording medium by flash discharge from a flash discharge tube.

FIG. 1 shows a flash fixing device in a conventional facsimile machine. Both ends of a charging/discharging capacitor 20 are connected to the + and - side output terminals of the high voltage generating circuit 1, and both ends of the capacitor 2 are further connected to both poles of a flash discharge tube 3.

The flash discharge tube 3 is opposed to a conveyance path of a recording medium (not shown) conveyed by a pulse motor (not shown). Note that the conveyance speed of the recording medium varies irregularly depending on the band compression processing of the facsimile machine.

, 4 is a high voltage pulse generation circuit that applies a high voltage pulse to the trigger input terminal of the flash discharge tube 3, and 6 is a voltage divider that divides the terminal voltage of the capacitor 2. 6 is a control circuit which inputs a charging start signal, a light emission timing signal and the output of the voltage divider 6, controls the high voltage generation circuit 1 and the high voltage pulse generation circuit 4 based on these signals, and also outputs a charging end signal. Output.

Next, the operation of this conventional circuit will be explained with reference to timing charts shown in FIGS. 2 and 3.

First, when the charging start signal falls, the control circuit 6 drives the high voltage generating circuit 1 and causes the circuit 1 to start charging the capacitor 2. When the capacitor 6 reaches a predetermined upper limit voltage VH due to this charging, the control circuit 6 detects this via the voltage divider 6, causes the high voltage generation circuit 1 to finish charging the capacitor 2, and sends a charge end signal. Make me stand up. When the charge end signal falls in this way, the charge start signal rises.

After charging is completed as described above, when the light emission timing signal is input to the control circuit 6, the control circuit 6 drives the high voltage pulse generation circuit 4 to trigger the flash discharge tube 3 from the generation circuit 4. Apply Takatsuki Yupulse to the input terminal as a trigger. Then, the gas in the flash discharge tube 3 is ionized, the insulation between the positive and negative electrodes in the discharge tube 3 is broken, and the charge accumulated in the capacitor 2 is discharged between the two electrodes all at once, resulting in a flash discharge. will be held.

This fixes the toner image on the recording medium. Note that when the light emission timing signal is input, the charge end signal rises. Further, when a predetermined period of time has elapsed after the light emission timing signal was input, the charging start signal falls again, and the control circuit 6 causes the high voltage generating circuit 1 to charge the capacitor 2 again. Thereafter, the same operation as described above is repeated.

Here, since the flash discharge of the flash discharge tube must be performed every time the recording medium is conveyed a predetermined distance (fixing width), the light emission timing signal is used to drive the pulse motor as many times as the number corresponding to the fixing width. When a pulse is sent out, it is output. However, as soon as the charging of the capacitor 2 is finished as described above, the electrical energy stored in the capacitor 2 gradually decreases due to the natural number of charges. Therefore, if the time from the end of the charging to the next light emission timing signal becomes long, the required electrical energy will be flash discharged from the capacitor 2 when the next light emission timing signal is output. It will no longer be possible to output to tube 3.

Therefore, as clearly shown in FIG. 3, when the control circuit 6 detects via the voltage divider 6 that the voltage of the capacitor 2 has dropped to the predetermined auxiliary charge starting voltage vL due to natural discharge, the same occurs. The control circuit 6 internally causes the supplementary charge start signal to fall and drives the high voltage generating circuit 1 to start supplementary charging to the capacitor 2. If the voltage of the capacitor 2 reaches the upper limit voltage vH again due to this supplementary charging, the control circuit 6 causes the high voltage generating circuit 1 to terminate the supplementary charging.

Note that the control circuit 6 performs the supplementary charging only when the voltage of the capacitor 2 reaches the supplementary charging start voltage vL after the charge end signal falls and until the next light emission timing signal is output. Therefore, even if the voltage of the capacitor 2 reaches the auxiliary charging start voltage vL during the charging or flash discharge, the auxiliary charging is not performed.

By performing supplementary charging as described above, the voltage of the capacitor 2 is kept at the upper limit voltage v from the time the charging of the capacitor 2 is completed until the next light emission timing signal is output.
H and the supplementary charging start voltage vL. This allows the capacitor 2 to always output the required electrical energy to the flash discharge tube 3 when the light emission timing signal is output.

However, since the discharge starting voltage of the flash discharge tube 3 in each flash discharge varies between vH and vL, the energy output from the flash discharge tube 3 in each flash discharge is
It varies in a corresponding range between VH and vL. That is, the electric energy flash discharged in the flash discharge tube 3 is 1/2Cv2 (Q=capacitance of the capacitor 2, V
The energy output from the discharge tube 3 during each flash discharge is 1/2.
It will vary within the range of CV to 1/2CvL.

In the past, the difference between the maximum and minimum output energy of the flash discharge tube 3 was several percent, which had the drawback of causing uneven fixing.

In order to reduce fluctuations in the output energy of the flash discharge tube 3, it is sufficient to reduce the difference between vH and VL. However, if this difference is reduced, the number of supplementary charging increases significantly, resulting in a significant increase in power consumption. (During charging, overcurrent flows, so as the number of supplementary charging increases, power consumption increases).

Since VHIVL is still a high voltage, it is actually difficult to set the difference between VH and vL to be smaller than a certain level.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a flash fixing device that can reduce fluctuations in the output energy of a flash discharge tube without increasing power consumption. .

The flash fixing device according to the present invention focuses on the fact that there is little change in the conveyance speed while the recording medium is conveyed by the fixing width, and the flash fixing device according to the present invention takes into account the time required for auxiliary charging every time a flash discharge of the discharge tube is performed. The distance that the recording medium is conveyed during a predetermined time set by This system performs supplementary charging on the charging/discharging capacitor even when the charging/discharging capacitor is

The present invention will be described in more detail below based on embodiments shown in the drawings.

FIG. 4 shows an embodiment of the present invention.

In the same figure, blocks that are the same as or correspond to the conventional circuit of FIG. 1 are indicated by the same reference numerals.
High voltage generation circuit 1, charging/discharging capacitor 2, flash discharge tube 3,
The high-voltage pulse generating circuit 4, the voltage divider 6, and the control circuit 6 are connected in the same manner as in the conventional circuit.

However, the control circuit 6, in addition to performing the same control operations as the conventional one, also receives pulse motor drive pulses and performs the following control based on these pulses.

That is, when the control circuit 6 inputs the light emission timing signal, it counts the number x2 of pulse motor drive pulses input during a period of time t1 from that point. Here, the above 11 hours is calculated from vL to vH-!, which is measured and determined in advance. ! This is the time required to auxiliary charge the capacitor 2 at , (tl is about 0.1 to 0.2 degrees. By the way, due to natural discharge, the capacitor changes from -1-limiting voltage vH to auxiliary charge starting voltage vLK-!, 2 voltage drops is about 30 seconds), therefore, the number of pulses x 2
By counting , the distance traveled by the recording medium during the 11 hours required for the supplementary charging is measured.

Then, the control circuit 6 continues to count the pulse motor drive pulses even after time t1 has elapsed, and when xl is the number of pulse motor drive pulses required to convey the recording medium by the distance of the fixing width, From the moment when the timing signal is input, the pulse motor drive pulse is changed to C11-x2.
), it generates an auxiliary charging start signal, and the high voltage generating circuit 1 counts the number of pulses x2.
4 and the above (xl ”2
) If the conveyance speed of the recording medium is the same in the period from the time of pulse count until the next light emission timing signal is input to the control circuit θ, the supplementary charging started from the time of pulse count (x, to x2). will be completed immediately before the next light emission timing signal is input.

Here, in reality, since the conveyance speed of the recording medium varies, there is a possibility that the difference between the end point of the supplementary charging and the point of the next light emission timing signal becomes large. but,
Normally, fluctuations in the conveyance speed of the recording medium in the fixing width are small, so the deviation does not become too large. Therefore, normally, the time point at which the supplementary charging ends is set immediately before the input time point of the next light emission timing signal, and the flash discharge tube 3 can be caused to perform flash discharge when the voltage of the capacitor 2 is close to the upper limit voltage vH. can.

For this reason, the output energy of the flash discharge tube 3 fluctuates as follows:
Before the IjIJ control circuit 6 counts the (x+-!2) pulses, the voltage of the capacitor 2 may drop from the upper limit voltage VH to the auxiliary charging start voltage VL due to natural discharge. , in such a case, the control circuit 6
As in the conventional case, supplementary charging is performed by detecting vL through the voltage divider 6, so that the voltage of the capacitor 2 does not drop by vL, 1:B during the flash discharge standby after the photoelectric discharge is completed.

In addition, in this method, the upper limit voltage vH and the auxiliary charging start voltage vL
Since there is no need to reduce the difference between Since it does not increase, power consumption does not increase.

In this embodiment, counting of the number of pulses x2 is started at the same time as the light emission timing signal is input.
(!1-X2) It goes without saying that counting of the number of pulses x2 may be started later than the light emission timing signal within a range that is in time for counting the number of pulses x2.

Further, the 14 hours may be appropriately shorter or longer than the time required to supplementally charge the charging/discharging capacitor 2 from VL to VH.

As described above, the flash fixing device according to the present invention measures the distance that the recording medium is transported during a predetermined time set corresponding to the time required for supplementary charging every time the flash discharge tube performs flash discharge. However, even when the recording medium has been conveyed by a distance obtained by subtracting the measured distance from the predetermined distance corresponding to the fixing width since the previous flash discharge, the charge/discharge capacitor is supplementally charged, thereby reducing the consumption. This provides an excellent effect in that fluctuations in the output energy of the flash discharge tube during each flash discharge can be reduced and uneven fixing can be prevented without increasing the power.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional flash fixing device, FIGS. 2 and 3 are timing charts of the same essential parts, FIG. 4 is a block diagram of a flash fixing device according to an embodiment of the present invention, and FIG. 6 is a block diagram of a conventional flash fixing device. This figure and FIG. 6 are timing charts of the same essential parts. 1... Output generation circuit, 2... Charging/discharging capacitor, 3... Flash discharge tube, 4...
・High voltage pulse generation circuit, 6...Voltage divider, 6...
...control circuit. @1 Figure

Claims (1)

[Claims] a flash discharge tube having both poles connected to both ends of a charging/discharging capacitor, means for causing the flash discharge tube to perform a flash discharge each time a recording medium to be fixed is conveyed a predetermined distance, and each flash discharge. The capacitor is charged every time the capacitor is charged, and when the voltage of the capacitor reaches a predetermined upper limit voltage, charging is stopped, and when the voltage of the capacitor drops to the predetermined auxiliary charging start voltage due to natural discharge. Ba,
a first charging control means for performing supplementary charging on the capacitor; and a first charge control means for performing supplementary charging on the storage medium; a second method that measures the distance over which the capacitor is conveyed, and performs supplementary charging on the capacitor even when the recording medium has been conveyed by a distance obtained by subtracting the measured distance from the predetermined distance since the previous flash discharge; A flash fixing device characterized by being provided with charging control means.