JP3152457B2 - Copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine using a commercial AC power supply having an exposure lamp and a heat fixing device, and more particularly to a copying machine provided with safety measures for the exposure lamp or the heat fixing device.

[0002]

2. Description of the Related Art Conventionally, a halogen lamp is often used as a light source for exposure (exposure lamp) in a copying machine.
By keeping the supply voltage to the halogen lamp constant, the light quantity becomes constant. However, since the commercial AC power supplied to the copying machine is not constant for various reasons, a constant voltage power supply called a lamp regulator is provided inside the copying machine. As a method of generating a constant voltage, an AC phase control method is often used. Conventionally, a triac (trade name) is often used as a phase control element.

As a fixing device used in a copying machine, a heat fixing device that melts toner and presses it against paper is generally used, and a halogen heater is used as a heating member. Unless the temperature of the heating roller heated by the halogen heater is maintained within a certain temperature range depending on process conditions such as toner, a high quality final image (copy) cannot be obtained. Therefore, in order to keep the temperature of the heating roller constant, the temperature of the heating roller is controlled by controlling the on / off of the triac by an electronic circuit such as a temperature detection element (thermistor), a current control element (triac), and a micro computer. .

[0004]

In the above prior art, the triac may rarely fail in the short mode. If a failure occurs in the short-circuit mode, the halogen lamp will be turned on and will not be used. Therefore, the continuous lighting detection circuit is activated, the main relay is opened, and the current to the lamp regulator is cut off, turning off the halogen lamp.However, the conventional continuous lighting detection circuit is about twice as long as the maximum transfer paper exposure time. Is regarded as an allowable exposure time, and if it is continuously turned on for a longer time, it is determined that an abnormality has occurred. For this reason, if the triac breaks down during normal standby, it lights up continuously for about 10 seconds and then acts as an abnormality.

[0005] Also, in the halogen heater, the triac breaks down and the halogen heater is not energized, or the positional relationship between the thermistor and the heating roller is poor, and the thermistor does not normally detect the temperature of the heating roller. The heater may be energized and stay on. In order to cope with such a case, a temperature fuse is provided near the heating roller, and the temperature fuse is inserted in series with the halogen heater. In this case, a fire does not occur, but the surface temperature of the roller is 250 to 300 ° C., and smoke may be emitted from the heating roller, which may cause unnecessary anxiety to the user. (The heating roller and the pressure roller) break the coat layer on the surface, and cannot be reused.

SUMMARY OF THE INVENTION An object of the present invention is to provide a copying machine having a safety device that operates reliably by checking the energized state of an exposure lamp (halogen lamp) or a heating material (heater) of a heating roller. .

[0007]

An object of the present invention is to expose a photoreceptor.
Exposure lamp to emit light, temperature fuse, and current control
Means and a current interrupting means are connected in series, and
Check the applied voltage at both ends of the loop to detect abnormalities
In a copying machine using a commercial AC power supply , the transformer is connected at regular intervals during copy standby and during copying.
Detects the output voltage of the transformer just before the exposure lamp is turned on.
When the output voltage is higher than a predetermined voltage,
Control means for turning off the current interruption means connected to the amplifier
This is achieved by a first means having:

[0008] In the first means, the output of the transformer
Voltage to keep the exposure voltage of the exposure lamp constant.
This is also achieved by the second means used as the feedback input signal of the pre-regulator .

Further, a heating roller for thermally fixing the toner on the transfer paper is used.
Heater, temperature fuse, and current control
Means and the current interrupting means are connected in series, and
Check the applied voltage at both ends to detect abnormalities.
For copiers using commercial AC power supply with lances connected
At regular intervals during copy standby, and during copy
The output voltage of the transformer is detected just before the
When the pressure is higher than a predetermined voltage, the heater is connected to the heater.
This is also achieved by the third means provided with control means for turning off the current cutoff means .

[0010]

[0011]

[0012]

In the first means, the output voltage of the transformer becomes a voltage value corresponding to the voltage applied to the exposure lamp, and the value is detected to determine the abnormality of the current control means. The control means
Exposure lamp is lit at regular intervals during copy standby and during copying
Immediately before the output voltage of the transformer is detected,
If higher, turn off the current interrupt
Turn off the light.

[0013]

In the second means, the output voltage of the transformer is also used as a feedback signal for keeping the lamp supply voltage constant.

In the third means, the output voltage of the transformer becomes a voltage value corresponding to the voltage applied to the heater, and the value is detected to determine the abnormality of the current control means. The control means
At regular intervals during copy standby, just before energizing the heater during copy
The output voltage of the transformer is detected during
If it is higher, the current interrupt means is turned off and the heater power is cut off
I do.

[0016]

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration of an embodiment of the present invention, wherein 1 is a halogen lamp as an exposure lamp, 2 is a photoreceptor which emits a light beam 3 emitted from the exposure lamp 1 and reflected on the document surface. An optical system consisting of a mirror 5 and a lens 6 leading to the drum 4; 7 a color separation filter selected according to the color of the developing toner; 8 a developing device for each color; 9 a transfer drum;
Reference numeral 0 denotes a fixing device including a pressure roller 11 for fixing the toner image on the conveyed transfer paper and a heating roller 13 having a built-in fixing heater 12, and reference numeral 14 denotes a feeder disposed in two upper and lower stages. A paper cassette 15 is a pair of registration rollers. Reference numeral 16 denotes a main control unit comprising a CPU, ROM, RAM, etc., 17 denotes a DC power supply circuit, 18 denotes a main switch,
Reference numeral 19 denotes a commercial AC power supply, reference numeral 20 denotes a drive circuit for driving the fixing heater 12 and the exposure lamp 1, and reference numeral 21 denotes a relay serving as a current interrupting unit.

FIG. 1 is a circuit diagram showing the structure of the drive circuit 20 shown in FIG. 2. The exposure lamp 1 and the fixing heater 12 have temperature fuses 22a and 22b, current control elements (triacs) 23a and 23b, respectively. The relay 21 is connected in series, and rectifiers 25a and 25b are connected to both ends of the exposure lamp 1 and the fixing heater 12 via transformers 24a and 24b and transformers 24a and 24b, respectively. A signal is output to an input terminal of a CPU (not shown) of the unit 16. In the figure, 26 is a thermostat, C ₁ and C ₂ are capacitors, and D is a diode.

Next, the operation of the above embodiment will be described. However, the copying operation of this embodiment is known as an electrophotographic process, and a description thereof will be omitted. The commercial AC power supply 19 is a drive circuit 2
0 is supplied directly to the DC power supply circuit 17 via the main switch 18, and the DC voltage output from the DC power supply circuit is supplied to the main control unit 16. Main control unit 1
Reference numeral 6 denotes a signal to which various switches, sensors, operation switches, and the like are input from the copying machine main body, and that the CPU controls the load of each part of the copying machine. Further, the main control unit 16 includes a driving circuit 2 for supplying driving power to the fixing heater 12 and the exposure lamp 1.
It is connected to 0 to exchange various signals.

The gates of the triacs 23a and 23b are controlled by the main controller 16. The voltage applied to both ends of the exposure lamp 1 is DC-converted by a transformer 24a and a rectifier 25a connected to both ends of the exposure lamp 1, and the main controller 1
6 is input to the input terminal of the CPU. The abnormality detection operation is divided into a standby mode and a copying mode, as shown in the timing chart of FIG. 3, and the analog input voltage is checked at regular time intervals (for example, 1 second) during the standby mode and immediately before the lamp is turned on during the copying. If the voltage is not close to zero volts, it is determined that the lamp is lit when it is not necessary, and it is determined that a triac failure has occurred, and the relay 21 is shut off. A transformer 24a and a rectifier circuit 25a connected to both ends of the exposure lamp 1 also serve as lamp voltage detecting means, and output a feedback signal (lamp voltage detecting signal) of a lamp regulator for keeping the lamp supply voltage constant. I do.

On the other hand, the control of the fixing heater will be described with reference to the timing chart of FIG. 4 and the flow chart of FIG. 5. When the exposure lamp 1 is turned off (N in S1), the gate of the triac 23b is set to the main control section. From 16, the driving is controlled based on the temperature information of the thermistor 26 (S 2). The voltage applied to both ends of the fixing heater 12 is detected by the transformer 24b, rectified by the rectifier 25b, and then input to the input terminal of the CPU of the main control unit 16. Further the input unit capacitor C ₂ for signal delay and waveform smoothing is provided.

When the lamp lighting start flag is on or the heater check time flag is on, both flags are turned off (S3), and the fixing heater 12 is shut off regardless of whether the heater temperature is lower or higher than the set temperature. (S4). That is, the energization of the triac 23b is cut off. Next, the output voltage of the transformer 24b is checked. If the voltage is close to zero volt (low level), the output is normal. If the voltage is not close to zero volt (high level), the output is abnormal (triac 23b).
Has failed in the short mode, etc.) (S5).
N), the relay 21 is cut off through the CPU (S6),
By shutting off the power supply to the drive circuit 20, safety can be ensured before the fuse fusing temperature is reached. Further, during the lamp lighting (Y in S1), the switching of the fixing heater 12 from ON to OFF or from OFF to ON is not performed, so that the voltage stabilization of the exposure lamp 1 is not hindered.

[0023]

Effects of the Invention] According to the invention 請 Motomeko 1 to 2,
Exposure lamp at regular intervals during copy standby and during copying
Immediately before lighting, the output voltage of the transformer is detected.
Is connected to the exposure lamp when the voltage is higher than a predetermined voltage.
To the current interrupting means in the disconnection state, to detect the transformer output voltage, an exposure lamp Ru can reliably control the power supply control to the (halogen lamp). According to the invention 請 Motomeko 3 wherein, during the copy standby regular intervals, also during copying heating
The output voltage of the transformer is detected just before
When the voltage is higher than a predetermined voltage,
Since the flow cutoff means is turned off, the output voltage of the transformer can be detected and the power supply control to the heater of the heating roller can be reliably performed, so that a highly safe copying machine can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a heater and an exposure lamp driving circuit according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating an overall configuration of the present embodiment.

FIG. 3 is a timing chart related to the operation of the exposure lamp.

FIG. 4 is a timing chart related to the operation of the fixing heater.

FIG. 5 is a flowchart for detecting a current control element abnormality.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exposure lamp 4 Photoconductor 12 Fixing heater 13 Heating roller 16 Main control unit 17 DC power supply circuit 19 Commercial AC power supply 20 Drive circuit 21 Relay (current interruption means) 22a, 22b Temperature fuse 23a, 23b Triac (current control means) 24a, 24b transformer 26 thermostat

Claims (3)

(57) [Claims] An exposure lamp for exposing a photoreceptor;
The temperature fuse, the current control means, and the current cutoff means are directly connected.
Connected in a row, and check the applied voltage across the exposure lamp for abnormalities.
In a copying machine that uses a commercial AC power supply and has a transformer connected for detection, an exposure lamp is used at regular intervals during copy standby and during copying.
Immediately before lighting, the output voltage of the transformer is detected.
Is connected to the exposure lamp when the voltage is higher than a predetermined voltage.
And a control means for turning off the current interrupting means . The output voltage of the transformer is controlled by the exposure
Lamp Regulator for constant light voltage
2. A copying machine according to claim 1, wherein said copying machine is used as a feedback input signal . 3. A heating roller for thermally fixing toner on transfer paper.
Heater, temperature fuse, and current control
The stage and the current interrupting means are connected in series, and the applied voltage is checked at both ends of the heater to detect an abnormality.
Using a commercial AC power supply with a transformer
For copying machines, heaters are turned on at regular intervals during copy standby and during copying.
Detects the output voltage of the transformer immediately before
Current cutoff connected to the heater when the voltage is higher than
It characterized by comprising control means for the means disconnection state
Copiers.