JPS58195215A - Controller for heating temperature - Google Patents

Abstract

PURPOSE:To prevent surely overheat due to the short circuit of a transistor TR for sensor, by turning off a heater when a set temperature detecting signal reaches a preliminarily determined level even if the set temperature detecting signal is larger than a heater temperature detecting signal. CONSTITUTION:A voltage Vs of a common contact D at the time when a TR2 is turned off and TRs 4 and 5 are turned on is inputted to a microcomputer 20, and an A/D-converted digital value VDS is stored in an RAM. A set value VDP of a preliminarily determined level is stored in the RAM of the microcomputer 20. When the digital value VDS reaches the set value VDP, a heater 32 is turned off even if a set temperature detecting signal V2 is larger than a sensor temperature detecting signal V1, thus preventing the overheat. Thus, the overheat due to the short circuit of the TR2 for sensor is prevented surely.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating temperature control device KIIL, particularly a sensor O.
The present invention relates to a heating temperature control device that prevents overheating of a heating section even when a switching transistor is short-circuited.

As a heating temperature control device, for example, there is a device that controls the heating temperature of the copying machine's lt deposition section, and as shown in FIG. A sensor 1 such as a thermistor having a decreasing negative resistance characteristic, a comparison resistor R1 inserted in series with the sensor 1, a capacitor C that absorbs noise mixed in from the lead wire of the sensor 1, etc., and a control device on the base. The F register 2.4 is turned on and off by inputting a pulse, the variable resistor 3 sets the heater temperature, and the reference resistor R2 is placed in series with the variable resistor 3 (Rt is several kiloohms, RLr is several As 100 Oh! * Set the condition of R1 > nz), and the nine transistors inserted between the reference resistor R2 and the ground 5
have.

History K, the output of the common connection point is from the microcomputer (CPU・11 (
aM, with PAM) 20 pure converter inputs AI
and output interfaces Pl, P2 . A control pulse is applied from Ps via pace resistors 6, 7, 8 to the pace of transistor 4.2.5. Also resistance 9.
The analog reference voltage set by the divided voltage based on 1θ is input to the microcomputer's converter A3, and the heater control signal generated based on the calculations in the microcomputer is sent from the output interface P4 to the heater control relay (
output to (funds).

- power, imperial seal part A, ll light part B1 developing part C1 transfer part L)%
A cleaning section E1 and a constant latency section F are arranged around the photosensitive drum J.
It's wrinkled.

In the above configuration, the operation will be explained as follows.

(1) Mode in which the heater temperature (heater 32) is detected by the sensor IK Based on the program of kixrM in the microcomputer park (Signal Processor - CL outputs an on signal from boat P2.Pa, an on signal from boat Pl, The transistor 25 is turned on and the transistor 4 is turned off.In this state l, the divided voltage Vl (heater temperature #L detection @) at the common connection point is as follows.

That is, the resistance R1a B! The combined resistance I R1 >> Rz, so IR=R. Therefore, the divided voltage z becomes V1it Vl-]1:Vcc.

(RD is the resistance of centl) (2) A mode that detects the set temperature by setting it by a variable resistor.The on signal is turned on from the boat by the signal build-up based on the RoM program in the microcomputer park. A signal is output, transistor 4.5 turns on, and transistor 2 turns off. In this situation, the divided voltage vs at the common connection point is:

That is, when the combined resistance R=Rg (1) is satisfied, the divided voltage Vz (set temperature detection signal) becomes R2' (ELs is the set resistance value of the variable resistor 3).

The above modes (1) and (2) are set as shown in the flowchart in Figure 2, and the divided voltage V1. Vz is N
Converter input AIK is input and converted into A/1), converted into digital values VDI and VDw, and stored in RAMK. The digital values VDI and VDz are subjected to a comparison operation of VDI and )VD2 based on a predetermined program.

(a) VDI>■ If D2 is Yes, the control relay is turned off and the heater 32Yt is turned off.

(b) VDI) If VDI is No, the control relay (capital) turns on and turns on the heater blade.

Based on the above operations, VDI is brought close to VD1Kflk, and the heater temperature is controlled to reach the set temperature (in other words, the heater 32Vt is controlled so that the resistance value of sensor l, RD, becomes the set resistance value R$). According to the above device, the comparative resistor Rr has a high resistance of several kilohms, and in addition to temperature control, only transistor 2 is turned on to accurately detect l!r& of sensor 1. (even if the sensor l becomes high in resistance when the temperature is high).

However, according to this heating temperature control device, if the transistor 2 is short-circuited, the divided voltage v2 will be reduced.
-〃Support (R8〃Support is the parallel composite resistance value of resistance value R3゜RD) @KV1<V2 (VDI < V
), there is a risk that the control relay 30 (heater 32) may continue to be turned on and cause the heating element U to overheat.

The present invention is a companion to the above #1), St.
To prevent overheating from occurring when transistor 2 for 1 is short-circuited, even if the set temperature detection signal v2 is larger than the heater temperature detection signal Vl, the armpit detection compensation signal v3 is set.
The present invention provides a heating temperature control device that turns off the heater 32 when the temperature reaches a predetermined nine levels.

The heating temperature control device according to the present invention will be explained in detail below.

FIG. 3 shows a flowchart of an embodiment of the present invention, in which, in the configuration of FIG. 1, when transistor 2 is turned off and transistor 4.5 is turned on for a predetermined period of T seconds, Digital value VD obtained by adding voltage V8 to microcomputer ~■Converter input Am K input and converting it to A/1) f
Store in I f h'AM.

On the other hand, in the microcomputer 20, a predetermined level set value VDI) (a level set to prevent overheating in the heating section) is stored in RAMK, and the digital value VDs is set to a set value VDp. When K is reached, even if the setting i! Since the detection signal V2 is larger than the temperature detection signal Vl, the heater is turned off to prevent overheating.

As explained above, according to the heating temperature control device according to the present invention, when the set temperature detection signal reaches a predetermined level, even if the level of the set temperature detection signal is higher than the level of the heater temperature detection signal. Since the heater is turned off even when the senna is turned off, the F transistor for the senna can accurately prevent overheating of the island heating section.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a heating]1ii one-degree control device. Second
The figure shows a 70-char F showing heating Il & control operations, and FIG. 3 is a flowchart showing an embodiment of the present invention. Explanation of symbols 1...Senna 3...Temperature setting section (...Microcomputer)...Control relay proverb...Heater
Photoreceptor drum... Heating roll Patent applicant Fuji Xerox Co., Ltd. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A temperature setting section for setting the temperature of the heater, a temperature detection section for detecting the temperature of the heater, a wrinkle warming setting l1g, and a connection for arranging the temperature detection section in parallel with the power supply. A nine reference resistor is inserted between the reference point of the point and the ground, and the set temperature detection signal and the heater temperature detection signal output from the connection point are input, and the level of the heater temperature detection signal is determined by the set temperature detection signal. In a large apparatus, the scissors control section is configured to cut off the power supply when the set temperature detection signal level reaches a predetermined value. A heating temperature control device characterized by having a configuration that cuts off four heater electric cables when the temperature is below a set temperature detection signal level.