JPS6111778A - Device for controlling temperature of heat roller fixing device - Google Patents

Abstract

PURPOSE:To make control easy and to suppress an increase in cost by detecting the initial temp. on the surface of a heating roller in the stage of throwing a power source, setting the surface temp. according to the detected value and prohibiting the temp. control by a temp. detecting element until the surface temp. attains the fixing temp. CONSTITUTION:The temp. range up to the fixing temp. Ts is divided to regions A1-A3 and on times the corresponding heaters are designated as t1-t3. The heater on-times t1-t3 in the regions A1-A3 are so set that the surface temp. rises up to the fixing temp. Ts or above when the initial temp. TINT is at the lowest temp. of each region. Said time are so set that the surface temp. does not exceed the max. permissible temp. TMAX when the temp. TINT is at the max. temp. of each region. The heater 2 is turned on and off according to the output from a thermistor 3 when a timer TIN2 is timed up so that the surface temp. of the heating roller 1 is maintained at the fixing temp. The temp. control by the temp. detecting element is prohibited until the surface temp. attains the fixing temp. The waiting time is thus reduced at the low cost without being influenced by the responsiveness of the temp. detecting element and without requiring intricate control means.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a heating roller with a built-in heater, a pressure roller that is brought into pressure contact with the heating roller, a temperature detection element that detects the surface temperature of the heating roller, and The present invention relates to a temperature adjustment control device for a heat roller fixing device, including a control means for controlling the surface temperature of a heat roller to a fixing temperature according to an output from a temperature detection element.

Conventional Technology In a conventional heat roller fixing device, the surface temperature detection element is used to control the temperature from when the power is turned on until the surface temperature of the heat roller rises to the fixing temperature, taking into account the temperature rise due to overshoot. The heater was turned off when a predetermined low temperature was detected.

On the other hand, the heat roller fusing device has the disadvantage that it cannot perform the fusing operation until the fusing temperature has reached the fusing temperature. When this improvement is applied to the temperature control described above, the overshoot after the heater is turned off will increase due to the response delay of the temperature detection element, so the temperature at which the heater is turned off will be further reduced. I had to set it to a lower temperature.

Problems to be Solved by the Invention As mentioned above, when the temperature for turning off the heater is set low, when the initial temperature is slightly lower than this predetermined temperature, the heater on time is extremely short. As a result, the surface temperature of the heating roller does not rise to the fixing temperature, which is a problem.

In order to solve the above-mentioned inconveniences, new temperature control is required, which creates new problems such as the side arms becoming bulky and increasing costs.

Solve problems. Means for Solving the Problems In order to solve the above-mentioned problems and shorten the waiting time, the present invention provides means for detecting the initial temperature of the heating roller surface when the power is turned on, and a timer for setting the heater on time. The apparatus includes means for setting the timer value of the timer according to the detected value, and means for prohibiting temperature control by the temperature detection element until the surface temperature reaches the fixing temperature.

Function The present invention detects the surface temperature of the heating roller when the power is turned on, energizes the heater for the heater on time set according to the surface temperature, and continues temperature detection until the surface temperature reaches the fixing temperature. This prohibits temperature control by Motoko.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to a heat roller fixing device of a copying machine.

Figure 1 shows an outline of the heat roller fixing device, (1)
is a heating roller with a built-in heater (2), a thermistor (3) for detecting the surface temperature on the upper part, and a motor (4).
The door iron can be rotated. A pressure roller (5) is pressed against the heating roller (1) and rotates as a result of the rotation of the heating roller (1).

FIG. 2 shows a control circuit used in the temperature control device of the present invention, which is controlled by a microcomputer (MC) equipped with an A/D converter.

The heater (2) is connected to an AC power source via a triac (6), and the triac (6) is connected to an output port (
Pot') via the transformer (7). The thermistor (3) is a resistance (R1), (
*2) Through the bridge circuit formed by +(R3), the input port (A/D I), (A/D2
) is connected to the input capo) (A/Di),
A current corresponding to the resistance change of the thermistor (3) is input to (A/D2).

Next, a method of setting the heater on time in this embodiment will be explained using the graph shown in FIG.

In the figure, (Ts) is the fixing temperature (TINT), which is the initial temperature, and (TMAX) is the maximum allowable temperature. "heater·
The on-time may be set in one-to-one correspondence with the initial temperature (TINT), but in this embodiment, the on-time is set in a one-to-one correspondence with the fixing temperature (TINT).
The temperature range up to s) is divided into three regions, and each region (A
The heater on times corresponding to I), (A2), and (A3) are set as tt, tz, and ta, respectively.

Ta. In the figure, (TI') and (T2) are the boundary temperatures of each region.

Must.

Also, the heater on time tt, t2 . t:+ is the initial temperature (TI
When NT) is the lowest temperature in each area, the fixing temperature (Ts)
In order to increase the temperature above the initial temperature (TINT) or the maximum temperature of each region, the temperature must be set so as not to exceed the maximum allowable temperature (rMAX). That is, the area (
Taking A2) as an example, TI+n-t2+TOVer ≧Ts (third
Figure (a)) Tz+n-tz+Tover (TMAX
It is expressed by the approximate expression (FIG. 3(b)).

Next, the temperature control executed by the microcomputer (MC) in G1 is shown in Figure 4 (a+, (b), (C)).
This will be explained in detail using the flowchart shown in FIG. Note that the flowchart only describes parts related to the present invention, and other parts are omitted.

When the power to the copying machine is turned on, the microcomputer (MC) is initialized in step ■, a routine timer is set in step ■, and the initial temperature is set according to the output from the thermistor (3) in step ■. Detect and set the heater on time. Details of this process are shown in steps [phase] to 0.

After inputting in step (2), copying operations and trouble checking processes are executed in step (2). Since this process is not directly related to the present invention, its details will be omitted.

Subsequently, in step (2), processing for temperature control is executed. The details of this process are shown in steps ① to ②. After performing the output in step ■, step ■ counts the heater on time setting timer (TIMI) and thermistor temperature control prohibition timer (11M2), which will be described later, and waits for the end of the routine timer in step ■ to complete one routine. After finishing, return to step ■.

Next, the initial temperature detection process in step (2) will be explained.

When the power of the copying machine is turned on and the main flow starts, the output from the thermistor (3) is A/D converted in step [phase], and the initial temperature (TI NT
) is higher than the fixing temperature.

If it is determined as ``Yesj'' in step (2), the timer (11M2) end flag is set in step @ and the process proceeds to step (2), and if "NO", the process proceeds to step (2).

In step ■, the initial temperature (TINT) is the boundary temperature (T2)
Determine whether the temperature is higher than ``If YesJ, step Q
The timer (TIMl) is set to t as the heater on time.
3, and if "NoJ", proceed to step 2. In step 2, it is determined whether the temperature is higher than the initial temperature ("INT) or the boundary temperature (TI), and if f-YesJ, the timer is set in step [phase]. (TIMI) Set the
"If so, set the timer (TIMI) at step ■>
set. Then, in step ■, the timer (11M2
) is set, the heater (2) is turned on in step (2), thereby completing the initial temperature detection process. here,
The timer value of the timer (11M2) is the value obtained by adding a certain time to the heater-on time set in steps ①, [stock], and @, respectively.

Next, the temperature adjustment control process in step (2) will be explained.

In step 2, it is determined whether the timer (11M2) ends and the signal goes to G, or if the timer (11M2) end flag is set. By turning on and off the heater (2), the surface temperature of the heating roller (1) is controlled to maintain the fixing temperature.

Note that the temperature control using this thermistor is similar to the conventional one, so the details thereof will be omitted.

On the other hand, if the step ) is determined to be "NO", the step @ determines whether the timer (rlMl) has ended, and if it is Yes, the step knob turns off the heater (2). After that, if the answer is "NO", the process goes directly to step (2), and the temperature control process ends.

In this embodiment, a thermistor (3
), including but not limited to (
It is also conceivable to determine the initial temperature according to the time since the power was turned off. Further, although a timer (11M2) is used as a means for prohibiting temperature control by the temperature detection element, it may be prohibited until the fixing temperature is detected by the temperature detection element.

EffectsAs is clear from the above explanation (because the timer primarily controls the energization to the heater when the surface temperature of the heating roller rises, it is not affected by the responsiveness of the temperature detection element, and it does not require complicated processing). No control means is required, and waiting time can be shortened at low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing a heat roller fixing device according to the present invention, FIG. 2 is a circuit diagram of a temperature control device used in the present invention, and FIG. Graph explaining the time setting method, Figure 4 (al,
(bl, (C) is a flowchart explaining the present invention in detail. (1)...heating roller, (2)...heater, (3)
...Thermistor (temperature detection element), (Ts,) = constant temperature, (TINT) ... initial temperature. Applicant Minolta Camera Co., Ltd. Figure 1 2yA 3WJ Figure 4 (0-) 41gI (C) Procedural Amendment 1985 3B14 1, Indication of Case 1989 Patent Application No. 133519 2, Invention Name Temperature control device for heat roller fixing device 3, Relationship with the case of the person making the amendment Applicant address 2-30 Azuchi-cho, Higashi-ku, Osaka City Osaka Kokusai Building voluntary amendment 5, subject of amendment 81, Figure 2

Claims (1)

[Claims] 1. A heating roller with a built-in heater, a pressure roller that comes into pressure contact with the heating roller, a temperature detection element that detects the surface temperature of the heating roller, and a heating roller according to the output from the temperature detection element. In a temperature control device for a heat roller fixing device, the temperature control device includes: - a means for detecting the initial temperature of the heat roller surface when the power is turned on; and - a heater when the surface temperature rises.・A timer for setting the on time; ・Means for setting the timer value of the timer according to the detection value from the detection means; ・Prohibiting temperature control by the temperature detection element until the surface temperature reaches the fixing temperature. A temperature control device characterized by comprising: means.