JPS5965868A - Fixation temperature controller - Google Patents

Abstract

PURPOSE:To prevent a fault of fixation due to a temperature drop during paper feeding by holding the temperature of a fixation roll higher than set temperature within a specific range during copying operation. CONSTITUTION:The detected temperature output of the fixation roll obtained by a temprature detecting element 9 is compared with a reference value corresponding to temperature higher than the set temperature within the specific range and when the fixation roll does not arrive in this temperature, the output of a comparator 1 is at a high level. Further, an active high-level copy signal 15 allows the outputs of an inverter I1 and a timer 16 to rise in level during the copying operation. The output of an AND gate A2 is inverted to the high level by those high-level outputs, and even when there is not any output passed through a temperature controller 10, a driver 11 responds to the output of an OR gate OR1 during the copying operation to conduct a heater 2 for a specific time. Consequently, the temperature of the fixation roll is held higher than the set temperature within the specific range during the copying operation to prevent the fault of fixation due to a temperature drop during paper passing.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing temperature control device, and particularly to a temperature control device c7 for a fixing roller used in copying machines, printing machines, etc.

FIG. 1 is a simplified diagram showing a roller fixing device of a copying machine.

In the figure, 1 is a fixing roller having a heater 2 inside thereof, and a pressure roller 23 is in pressure contact with this roller. The transfer paper is
It moves in the direction of the arrow while being held between the fixing roller 1 and the pressure roller 3, and is transported between guide plates 5 by a pair of transport rollers 4.

The fixing roller 21 rotates to the left as shown in the figure.
A peeling claw 6, a cleaning blade 7, and a cleaning felt 8 are provided in order in the counterclockwise direction from the point of contact with the transfer paper (paper passing point), and the temperature detection element 9 is provided behind the cleaning felt 8. .

That is, the temperature detection element 9 is located farthest from the paper passing point.

In terms of temperature control, it is desirable that the temperature detection element 9 be located in the mermaid. However, at this position, the transfer paper has not yet been electrically peeled off by the peeling claw 6, and the transfer paper comes into contact with the temperature detection element 9. I wondered what would happen after the peeling claw 6,
At this position, the constant force q roller 1 has not been subjected to sagging +)-, so the temperature detection>+< child 9 may become dirty with toner, etc. 1. There is a risk. For this reason, the temperature detection element 9 has no choice but to be placed behind the cleaning felt 8, which is at a position fiJ'' after cleaning.

However, the temperature detection element 9 is located far from the paper passing point as described above. Therefore, the fixing roller 1, whose temperature has decreased due to the transfer paper passing therethrough and the transfer paper absorbing heat, recovers its temperature to some extent while reaching this position.

Therefore, the temperature detection system 9 cannot detect the drop in temperature of the fixing roller 1 at the actual paper passing point.

Furthermore, since there is also a thermal time constant of the temperature detection system 9 itself, a response delay occurs to some extent in addition to the influence of position.

FIG. 2 shows a temperature curve controlled by the set temperature Ill L. In the figure, T is the temperature detected by the temperature detector 9, and T is the actual 61A during paper passing at the paper passing point.
C8 indicates the copy start timing, and Ce indicates the copy end timing.

Furthermore, in the temperature waveform, ON indicates the timing at which the heater 2 is turned on, and OFF indicates the timing at which the heater 2 is turned off.

As shown in the figure, if copying is started at the off timing of heater 2, the temperature drop due to sheet feeding is Tll, -1
is very large and may cause fixing failure.

However, as mentioned above, the temperature detection element 9 detects a temperature 111 which is slightly higher than this drop temperature Tm-1 as shown by the broken line, so the machine detects this sudden drop temperature If This means that the control that deals with ll-1 will not be performed.

Note that t, 4 is the time from when the heater 2 is turned off until copying is started and when the heater 2 is turned on again.

The present invention was developed in view of the above-mentioned circumstances, and its purpose is to maintain the drop temperature of the trailing roller during paper passing by the fixing roller within a fixable range.

To this end, the apparatus is configured such that at the start of copying, a cohesive signal σ) is output, and at this time the temperature of the fixing roller is controlled to be higher than the set temperature within a certain range.

The present invention will be explained below based on an illustrated embodiment.

FIG. 3 shows the temperature sensor 4 according to an embodiment of the present invention. It is a control circuit.

In the figure, 10 temperature controllers are provided to control the set temperature by No. 4if from the temperature detection element 9, and the output thereof is an OR circuit OR1 (output 0), a driver 1
1, SS1 also drives the switching element 12, which is formed by 'tfL'G, and so on. The heater 2 is connected in series with this switching element 12 to Wa 'lJg'-13, and the switching element 1
2, it is now controlled on and off (・ro.

On the other hand, the voltage divided by the temperature detection system 9 and the resistor l is inputted to the e terminal of the comparator 14, and
The reference voltage [E], which is divided by the voltage regulator and R8, is applied to the -terminal of the regulator 14.This quasi-voltage is applied when the temperature of the fixing row 21 is 7G°C higher than the set temperature IIL. At a predetermined temperature (for example, set temperature + 5°C): 9+': 4JL so that the output ■ of the J regulator 14 becomes a low level.
It is also determined by IL3. Also, resistance. is for providing hysteresis.

In addition, when the copy signal 15 (for example, main motor operation No. Nokrunu is generated (output 03). This signal is input to the 2×Y☆:15 terminal represented by the trigger terminal of the timer circuit 16 composed of an IC555. Then, a pulse is output to the output terminal No. 3 at a time determined by the semi-fixed resistor V 1t and the capacitor C1 (output). This pulse width time is t
2, then σ)t2 is the above-mentioned t.

It is sufficient to set it to a longer length (11≧1+).

A1 is an AND circuit with three terminal inputs, and outputs CONNO (output from the regulator 14), INNO (from −1. to σ) output,
The output ■lJ'' from the timer circuit 16, which is to be inputted, is an inversion of the coherence signal 15, and since this copy signal 15 is an air current blow, in the end, Copy letter "t'157J-"
If it is output, the output ■ will be equal to the current level d.

Further, the output [F] of this AND circuit A1 and the output (2) of the temperature controller 10 are input to an OR circuit 0J (1).

Therefore, regardless of the presence or absence of the output (2) which is the set temperature control output, if the zero output from the AND circuit A1 is at a high level, the heater 2 is turned on. As mentioned above, the AND circuit A1 outputs a high level output when the output ■, the output ■, and the output ■ are all at a high level, and when both of these conditions are satisfied, the copy signal is output, i.e. , when copying is in progress and the temperature has not reached a predetermined temperature higher than the set temperature (this is called roller temperature).

Conversely, during copying, even if the temperature detected by the temperature detection cable 9 has reached the set temperature, the heater 2 will not heat up until a predetermined temperature higher than this, that is, the roller temperature is detected. This means that this will continue to be the case.

Normally, t1 has a time width that is sufficient for several sheets of transfer paper to be passed through the fixed roller 9.

Therefore, for example, when copying only one sheet, this copying time 1c is smaller than t, ℃・(tc<
+≦ tz) Therefore, when one copy is made continuously, the timer circuit 16 is activated every time, and the heater 2 is turned on continuously.When this happens, the temperature of the fixing roller 1 increases rapidly. , the temperature control function will be lost.In order to regulate this, the temperature control function is set. Then, turn on the heater 2 and then turn off the l!ml It'.

In this way, the temperature control function is not disturbed, and since the temperature is controlled higher than the set temperature, the temperature drop during copying can be reduced to a level that does not affect the performance of the J15M.

In addition, the timer circuit has 160 outputs.
Even if the copy signal 15 is inputted to the AND circuit A1, the heater 2 will be turned on when the copy force is completed. 1. C... After that, the temperature controller lO
Normally σ) set temperature control is performed.

FIG. 4 shows a timing chart from output (1) to specific output.

In the figure, C, , C, as mentioned above, copy start, copy! Katashishi indicates the timing of Shuryo, and W indicates the timing of copying.

Furthermore, in the output ■ which is the on/off output of the heater 2, (a) shows the part that is turned on by the timer circuit 16 under the Uj and I constraints, and (b) shows the part that is 116th from the set temperature,
The part controlled by the comparator 14 is shown. Further, '1+'2 is as described above.

In this timing chart, the first half C, 1
V with 1 copy operation (1 copy operation by user)
The waveform diagram for i and io copies is shown, and the second half c is a waveform diagram for the case of continuous copying of one sheet.

First, the first half will be explained.

During standby, the output ■ is controlled on and off. Then press the copy button (when the motor rotates,
When the output ■, which is a copy signal, becomes a low level, and conversely, the copying is completed, an error occurs. When this output (2) becomes low level, the output (2), which is a trigger pulse, is applied to the timer circuit 16, and the timer is started. Then, the output becomes no-repel, and the -force output ■, ■ becomes no.
Since the current level is low, the output of the timer circuit 16 is directly passed through the OR circuit ORI to set the output (2) to the low level and turn on the heater 2.

As mentioned above, the part indicated by (a) of the output 0 corresponds to this.

Next, the second half will be explained.

In this case, since the output ■, which is copy number 41 in one copy cycle, is smaller than t2, the timer circuit 16 operates every copy cycle. Then, the temperature, which was initially lower than the set temperature, gradually rises because heater 2 is mostly on. However, when the sieve roller temperature reaches the set temperature, the condenser rake 14 becomes low level, so the output [F] is not output from the AND circuit A1 (and eventually the output (2) of the timer circuit 16 is cut off). .

In this way, it is possible to control the temperature within a certain predetermined range even when copying one sheet continuously.

FIG. 5 shows a temperature characteristic diagram according to the present invention,
A (broken line) is the temperature drop when paper is passed while the heater 2 is on, and b is the temperature when the heater 2 is off. ′
As mentioned above, l'1 indicates the set temperature, and C indicates the copy start, but Illc is the judgment temperature of the comparator 14, and indicates the set temperature IAII and I1 false roller temperature.

Furthermore, (1) shows a case where several tens of copies are made in one copy operation, and (2) shows a case where one copy is made continuously.

As is clear from the figure, even when the heater 2 is on, the temperature drop γ, 1^ degree during paper passing can be suppressed to the same level as the temperature drop when the heater 2 is on.

As described above, the present invention controls the temperature of the fixing roller during copying to be higher than the set temperature within a certain predetermined range. It is possible to eliminate the situation.

[Brief explanation of drawings]

FIG. 1 is a simplified diagram of a roller fixing device 13 to which the present invention is applied, FIG. 2 is a temperature characteristic diagram according to a conventional example, FIG. 3 is a control circuit diagram according to an embodiment of the present invention, and FIG. The timing chart of the output waveform in the 3N6 section and FIG. 5 are temperature characteristic diagrams according to the present invention. 1... Fixing roller, 2... Heater, 9...
...Temperature detection tag, 10...Temperature control 'i'llll device constituting the temperature control circuit, j2...Switching photon, 13...'C6 eclipse, 14... Comparator as a detector, 15... copy signal,
16... Timer circuit, '1゛,... Set temperature, Tc... Roller temperature.

Claims (1)

[Claims] tli, a heater is connected to the source via a switching element, and the heater is controlled via the switching means with the output of a temperature control circuit including a temperature detection element that detects the temperature of the fixing roller, and the heater is built in. In the roller fixing device that controls the temperature of the fixing roller to a set temperature,
It has a timer circuit that outputs an output for a certain period of time when a copy signal is output, and a detector that detects a predetermined roller temperature higher than a set temperature, and during copying, the heater is energized until the roller temperature is reached. A fixing temperature control device 1B characterized by the following.