JPS59231573A - Control method of fixation temperature of copying machine or the like - Google Patents

Abstract

PURPOSE:To prevent the overheating of a fixation roller, defect of fixation, etc., by employing continuous control and discontinuous control together for temperature control over a fixing device. CONSTITUTION:When a copying machine is powered on, the current roller surface temperture te is room temperature tb, so the fixing device is heated under proportional control. The temperature is further raised under the proportional control even after the roller surface temperature exceeds lower-limit temperature td of fixation to approximate optimum fixation processing temperature ta, and the surface is held at the temperature ta until a copy start signal is inputted. Once the copy start signal is inputted, the heating of the fixing device is switched to two-position control, which is carried on until copying operation is completed to hold the surface at the optimum fixation processing temperature ta. Consequently, the overheating of the fixation roll due to an overshoot, defective fixation due to a temperature drop during continuous copying, etc., are prevented.

Description

Detailed Description of the Invention [Minute hand for industrial use] This invention applies to a fixing temperature control method for copying machines, etc. [Prior art] In the temperature control of copying machines, etc. There are four types of temperature control that are important for obtaining stable and high-quality copies. The fixing device includes a hot plate type, a heated roller type, etc., and is heated to a high enough temperature and heat to fuse the toner that has been placed in the image form on the transfer paper in order to fix it on the transfer paper. One method requires an appropriate amount of pressure. In general, the temperature of the fixing device is 150 to 150°C, which explains the heat roller method.
Unless stable control can be achieved within the range of 20QC and 1 degree, there will be no damage. If the temperature gets any warmer than this, the transfer paper will burn, a development called hot offset will occur, the toner will adhere to the roller, and the material that makes up the roller will become fatigued and pass through. This may impair the adhesion of Teflon or silicone rubber to the roller core material, leading to a decrease in the durability of the fixing device.Also, in these heat fixing devices, the The fixing process is not immediately possible after the power is turned on, and one preheating time (warming-up time) is required. This time is determined by the heat capacity of the fixing device, the set temperature for fixing processing, the external environment, the temperature control method, etc., but it is desirable that the warming-up time be short. Furthermore, during the fixing process during copying, contact with transfer paper having a temperature similar to that of the outside air takes away heat from the surface layer of the p-ra, causing the surface temperature of the p-ra to drop. In some cases, the temperature may drop below the fixable minimum temperature, resulting in a p1 fixing impossible state.

Therefore, the temperature control of a fixing device with a heat source such as a copying machine must be controlled to maintain a predetermined temperature as much as possible, taking into account the above point 11, and the warming up time after power is turned on is short. In addition, during the fixing process, it is preferable to control the temperature so that a drop in temperature can be suppressed. As a temperature detection method for temperature control, a detection element such as a pair of thermistors 1 and 2 is attached in contact with or near the roller part of the fixed load rt, and temperature information is sequentially sent to the temperature control circuit. .

Up until now, the two-position control method, which is a discontinuous temperature control method, and the proportional control method, which is a continuous temperature control method, have been adopted separately. Whether it is optimal depends on the shaft stopper of the copying machine, etc., the copying speed, copying size, etc., the set temperature of the barrel, the Shimada-ra member of the constant % 1 device, the size of the p-ra, etc. be.

The above-mentioned continuous temperature control is a temperature control method in which the heating part is activated and the amount of heating is controlled. In the case of the apparatus, as shown in FIG.
Set a temperature (proportional band) within the temperature range Tp, and normally perform maximum heating until the proportional band lower limit temperature tc is reached, which is within the proportional band and below a certain set temperature Btts within the proportional band. In this case, it refers to a temperature control method in which R67 is applied in proportion to the difference from im.

Furthermore, the above-mentioned discontinuous temperature control is a temperature control method in which a finite number of heating amounts are determined in advance, and which heating amount is used at each point is controlled. The two-position control is called ON-OFF control, and is the simplest method that uses only the two poles of zep and maximum possible heating as the heating amount of the finite oak.

Conventionally, as mentioned above, only one of the two-way control and the proportional control has been used to control the fixing rotation rate of a copying machine.

As shown in Fig. 2, two-position control has the disadvantage that if the heating amount is increased in an attempt to decrease the warming-up time t, there will be a large overshoot immediately after warming-up as shown in A, and there will also be large ripples even in a steady state. However, it has the advantage of being easy to start up.
In addition, proportional control has the disadvantage that it cannot cope with sudden temperature changes, that is, it has poor start-up speed, and has a small overshoot of warming-up Thm.
It has the advantage of having almost no ripples in steady state. Therefore, in the case of a fixing device that uses only two-position control, there is a drawback that the high temperature caused by the auto/merger chute may damage the fixing roller, and in the case of a fixing device that uses only proportional control, there is a risk of sudden damage during continuous copying, etc. It is slow to react to temperature changes, and in some cases it may become impossible to take close-up pictures.
In this case, there is a drawback that the speed of the copying operation is substantially reduced.

[Purpose of the invention]

This invention eliminates the drawbacks of the conventional control methods as described above, uses the advantages of each control method, performs stable temperature control during M, and prevents overheating of the fixing p-ra and defective fixing. [Structure of the Invention] The present invention provides a method for controlling the fixing temperature of a fixing device in a copying machine, etc. by continuous control and discontinuous control. Chills when used in combination with and t.

[Embodiments of the invention]

Below, this invention will be explained based on the drawings. Fig. 3 shows the relationship between the p-ra surface temperature of the fixing device and time, and Fig. 4 shows a flowchart of the operation for switching between proportional control and two-position control. is shown υ, and in Fig. 3, the solid line part l
represents proportional control, and the broken line portion 2 represents two-digit division.

First, when the copying machine or the like is powered on, since the surface temperature a-ra is the cold temperature tb, the fixing device is heated to the maximum by proportional control. As a result, the p-ra surface humidity te increases, and heating is continued even after it exceeds the lower limit fixable temperature td. In this case, the roller surface temperature I! Fixing can be started as long as Lt exceeds the lower limit temperature for fixing td, but if fixing is started at this point, the temperature will drop during continuous processing and insufficient fixing will occur immediately, making it unreliable. Therefore, until the temperature reaches the optimum fixing processing temperature ta, the copy start display, which is a warm-up completion display, is not displayed. Therefore, even after the fixable lower limit temperature td is exceeded, maximum heating is further performed by proportional control to raise the temperature, and when the roller surface temperature to reaches a temperature equal to or higher than the proportional band lower limit temperature fjl tc. If the determination circuit makes a determination, heating is performed by proportional control according to the temperature difference from the optimum fixing processing temperature ta to bring the p-ra surface temperature to closer to the optimum fixing processing temperature ta. When the optimum fixing temperature ta is reached, a copy start message is displayed and the roller surface temperature t@total optimum fixing temperature 1gK is maintained by proportional control 1 until a copy start signal is input.

When the copy start signal is input, the fixing device starts the fixing operation, and the heating of the fixing device, which has been performed by proportional control, is switched to be performed by two-position control.

As a result, even if the roller surface temperature is lowered due to heat being taken away by the object to be copied, the roller surface temperature is quickly <N! , suitable fixing temperature t
In this way, until the copying is completed, that is, until the set number of copies are completed, the p-ra surface temperature t@ is maintained at the optimum fixing processing temperature t& by second-position error control. Ru. Further, when the set number of copies has been completed, the second copy control is switched to the proportional control in response to a completion signal. In this way, when switching from two-position control to proportional control, that is, during standby, the roller surface temperature te is absorbed by the object and decreases, so the roller surface temperature to is set at the optimum fixing process. The temperature is maintained at ta.

Also, under some conditions when copying a large amount of poems, the roller surface temperature to
is proportional leucorrhoea IIl! If the temperature is lower than te, can copying be performed reliably even if it is higher than the minimum fixable temperature td? Il
- In order to obtain this, the copy start display is completely erased.

In the above embodiment, the power is turned on and p is controlled by proportional control.
- Ra table temperature te f: After rising, the proportional control was switched to two-position control by inputting the copying start signal, and when the inputting of the copying start signal stopped, proportional control was performed as long as the power was turned on. , without limitation, once the copying start signal is input, the roller surface temperature to is always adjusted to a temperature close to the optimum fixing humidity ta by two-position control, regardless of the presence or absence of the copying start signal, until the power supply is stopped. This means that the roller surface temperature t can be maintained at
If there is a risk that the temperature e may drop below the lower limit fixing temperature tc, the roller surface temperature te is returned to the optimum fixing processing temperature ta during the short interval by the two-position control of the button, and the roller surface temperature to may drop. When the amount is small, proportional control is performed.

Second-rank control is effective for Sugi 3, which processes a large number of copies, because the temperature rise is slow, and proportional control is less dangerous, such as oatmo shoots, so it improves the safety of the fixing device. It is effective for models that pay attention to intentionality and constant likelihood deviations.

〔Effect of the invention〕

This invention uses continuous temperature control and discontinuous temperature control in humidity control of copying machines, etc., and in particular uses proportional control and second-most difficult temperature control. It eliminates drawbacks such as overheating of the fixing p-ra due to auto shoot during warming up and poor fixing due to temperature drop in the fixing device during continuous projection, and enables stable temperature control, thus greatly increasing the reliability of copy stock etc. It has excellent effects such as:

[Brief explanation of the drawing]

Figure 1 shows the relationship between roller surface temperature and time when only proportional control is used, and Figure 2 shows the relationship between surface temperature and time when only two-position control is used. figure,
The 'tba diagram is a diagram showing the relationship between the roller surface temperature and time according to an embodiment of the present invention, and the tAa diagram is a four-chard diagram showing an embodiment of the present invention. ta=Optimum fixing processing temperature tb - P-Ra surface temperature te before power is turned on Proportional band lower limit temperature td... Lower limit temperature for fixing processing te... P-Ra surface uri wetness after power is turned on A + Hibiki - O / Seishuto l1lp ... At a temperature that allows fixing Fig. 1 11 - Fig. 2 □ Fig. 3 Fig. 4

Claims (1)

[Scope of Claims] 1. A fixing temperature control method for a copying machine, etc., characterized in that temperature control of a fixing device in a copying IelA hemorrhoid is carried out by continuous control and discontinuous control. 2- The temperature is controlled by the continuous control after the power is turned on until the first fixing process is started, and the temperature is controlled by the discontinuous control until the power is stopped after the first fixing process starts [11]. A fixing temperature control method for a copying machine, etc., according to claim 1, wherein the continuous control is proportional control, as described in any one of claims 1 or 2. A method for controlling the fixing temperature of a copying machine, etc. 4. A fixing temperature control method for a copying machine or the like according to claim 1 or 2, wherein the discontinuous control is a two-position control.