JPS644116Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image forming apparatus for forming color images.

A color copying machine will be explained below as an example. In general, the toner layer on the copy paper that forms the copy image in this type of copying machine is multi-layered depending on the number of colors, so if it is fixed while moving at a constant speed, thick layers will not be fixed sufficiently, and conversely, thin layers will not be fixed. If it overheats too much.

The present invention was developed in view of the above points, and is a color image formation system that is configured to fix monochrome images and multicolor images in their respective optimum conditions, and at the same time, allows jam detection to be performed easily and reliably. The goal is to provide equipment.

That is, the present invention provides a color image forming means for forming a color image on fed paper, a paper conveying means for conveying the paper on which the color image is formed by the color image forming means, and a paper conveying means using the paper conveying means. It has a fixing means for fixing a color image on the paper being conveyed, and a selection means for selecting the moving speed of the paper conveyance means, and the selection means determines whether the color image formed on the paper is monochromatic or The moving speed of the paper conveying means is variable depending on whether the paper is multi-colored,
Furthermore, there is a pulse generating means that repeatedly generates pulses in synchronization with the paper conveying operation of the paper conveying means, a paper detecting means provided at a specific position on the paper conveying path, and a means for detecting whether or not the paper has normally arrived at the detecting means. and determining means for determining whether the paper transport means is moving at a speed determined by the selection means based on the detection output of the paper detection means and the amount of pulses generated from the pulse generation means. The present invention provides a color image forming apparatus characterized in that it is configured to determine whether or not paper is being conveyed normally.

This makes it possible to perform optimal fixing for both monochrome and multicolor images, and to easily and reliably detect jams without requiring a complicated configuration even when the moving speed of the paper conveying means changes. I can do it.

For example, in a color copying machine, when performing multi-color copying and single-color copying (image formation using one color out of multiple colors), the moving speed of the copy paper in the fixing device is set so that the moving speed of the copy paper in the multi-color mode is slower than the monochrome mode. This makes it variable.

Specific embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a color copying machine to which the present invention can be effectively applied.
3 is an optical system, 4 is a color separation filter, 5 is a cleaning blade for the photosensitive drum, 6 is a DC charger, 7
is an AC exposure static eliminator, 8 is a photosensitive drum, 9 is a transfer drum, 10 is a separation claw, 11 is a fuser heater,
Reference numeral 12 designates a conveyor belt within the fixing unit, 13 a post charger, 14 an adsorption charger, 15 and 15' paper feed rollers, 16 and 16' copy paper, and 17 to 19 developer. The original image formed on the photosensitive drum 8 is visualized by a developer, wrapped around a transfer drum 9, and transferred onto copy paper. In the case of monochrome copying, copy sheets are sequentially fed to a transfer drum, a visible image is transferred thereto, separated by a separating claw 10, and moved within a fixing device 11 by a conveyor belt 12. In the case of multi-color copying, one color is sequentially transferred to the copy paper on the transfer drum each time the photosensitive drum rotates, and a full-color image with three superimposed colors is formed. The copy sheets are then separated by separation claws 10 and moved within the fixing device by a conveyor belt.

In the case of multiple colors, the speed of the conveyor belt is reduced to about 1/3 as required compared to the case of single colors, and the copy paper is sufficiently fixed in the fixing device before being discharged.

Conveyance within the fixing device schematically illustrated in FIG. 2 will be explained. 21 is a carry-in roller disposed at the entrance of the fuser; 22 is a photoelectric unit consisting of a light projector light-receiving element for detecting the copy paper being carried into the fuser; 12 is a conveyor belt; 24 is a fuser conveyor belt drive motor;
5 is a heater, 26 is an electric circuit that controls the heater, 27 is a photoelectric unit for copying machine detection provided at the exit of the fixing device, 28 is a delivery roller provided at the exit of the fixing device, 29 is a belt drive motor control circuit, and 23 is a fixing device. Temperature detection element to keep the internal temperature constant,
Reference numeral 31 indicates a disk mechanically connected directly to the conveyor belt drive motor, and 32 indicates a photoelectric unit for detecting the slit 33 provided in the disk.

To explain the operation, the copying machine sent to the fixing device is detected by the photoelectric unit 22 and is conveyed within the fixing device according to the movement of the motor 24 and the belt 12 whose speed is controlled according to the number of colors to be copied. Then, the toner layer is melted by a heater 25 controlled at an appropriate temperature.
The image is fixed and detected by the photoelectric unit 27 before being discharged. At this time, since the number of slits is counted according to the movement of the belt, the distance equivalent to the movement of the copy paper 20 is detected by the pulses from the photoelectric unit 32.
Since the moving distance between the photoelectric units 22 and 27 when the copy paper is normally conveyed is constant regardless of the conveyance speed of the copy paper, the photoelectric unit 27 does not operate after the belt moves corresponding to the moving distance. A jam signal is then generated as shown in FIG. 4 below.

FIG. 6 shows an example of a control circuit for the drive motor 24 and the fixing heater 25. That is, the moving speed of the copy paper is changed by changing the switch 61, and the energization of the heater is controlled by a jam signal, which will be described later.

Here, since the resistor 62 is larger than 63, in the case of multicolor copying, the switch 61 is set to the L side to reduce the energization angle of the motor by the tri-attack, thereby slowing down the conveying speed of the copy paper.

The heaters H ₁ to _{H 3} are maintained at an appropriate fixing temperature by a well-known temperature control circuit 26, but a jam signal opens the normally closed contact 46' and the heaters are shut off regardless of the temperature control circuit to ensure safety. be done.

Figure 3 shows an example of the circuit of each photoelectric unit. When light is projected onto the phototransistor 34, the collector potential decreases, the output PH of the comparator 35 becomes high level, and conversely, the light is blocked. The collector potential becomes high, and the level of the output of the comparator 35 decreases. This output is sent to the photoelectric units 22, 27 and 32.
PH-IN, PH-EX, and PH-M respectively for
shall be.

Figure 4 shows the signal PH when the copy paper reaches the inlet of the fixing device.
−IN generates pulse signal PH from disk 31 in Figure 2.
-Start integrating M, and when it reaches an integral value corresponding to the distance from the inlet to the outlet, the heater is to be shut off,
However, if the copy paper ejection signal PH-EX is generated before then, it will not be shut off. That is, the flip-flop 37 is set by the signal PH-IN, and the monostable multivibrator (hereinafter referred to as monostable multi) 3 is set by the pulse PH-M synchronized with the rotation of the motor.
8 is activated.

The output Q of the flip-flop 37 becomes a high level, and the AND gate 39 outputs the pulse together with a pulse of constant width from the monostable multi. The capacitor 40 is sequentially charged with this pulse charge. When the copy paper passes normally through the fixing device and reaches the exit, the flip-flop 37 is reset by the signal PH-EX. Therefore, the output Q becomes a low level and the charge on the capacitor 40 is transferred to the diode 41.
Discharge occurs through resistor 42. Therefore, the potential of the capacitor 40 does not reach the slice level set by the resistor 43, and therefore the comparator 44 does not produce an output.

However, if the copy paper is jammed due to accumulation in the fuser, the flip-flop is not reset because the exit signal PH-EX is not output, and the voltage of the capacitor 40 rises due to the accumulation of pulses and exceeds the slice level. Therefore, the output of comparator 44 becomes high level, thyristor 45 becomes conductive, and relay 46 is activated. The relay 46 continues to operate due to the characteristics of the thyristor and turns off the heater. In other words, the 6th
In the figure, since the normally closed setting 46' of the relay 46 is opened, the heaters _H1 to _H3 are stopped and ignition is prevented.

Here, as the moving speed of the copy paper, that is, the driving speed of the conveyor belt changes and slows down, the pulse interval increases in proportion, but the integral value corresponding to the distance between the inlet and the outlet does not change. Therefore, by setting the slice level in advance according to the distance between the inlet and the outlet, accurate jam detection can be performed even if fixing is performed at different moving speeds or even if the moving speed changes during the fixing operation.

Figure 5 shows another embodiment that is applied when the copy paper stops on the photoelectric unit at the exit and is not completely ejected, and if it does not disappear even after a necessary period of time after the exit signal PH-EX is generated, it is the same as above. The pulse signal PH-M from the disc is then integrated, and a jam on the photoelectric unit is detected based on the integrated value corresponding to the length of the copy paper.

In other words, when the exit signal PH-EX is generated, the AND gate 52 outputs that pulse together with a pulse of constant width from the monostable multifunction device operated by the pulse signal PH-M. The capacitor 53 is sequentially charged with these pulses.

When the copy paper passes normally through the exit unit and is ejected, the signal PH-EX becomes low level, so the charge in the capacitor 53 is transferred to the diode 54 and the resistor 55.
is discharged through. Therefore, the + signal input to the comparator does not reach the slice level and the comparator does not produce an output.On the contrary, when it stops on the exit unit, the voltage on capacitor 53 continues to rise and the high level + signal causes the comparator to operates and generates a jam signal as shown in FIG. In this case as well, even if the speed of the copy paper passing through the exit unit is different and fluctuates on the way, a jam can be detected without malfunction.

The monostable multipliers 38 and 51 are provided to prevent errors due to the PH-M pulse width varying depending on the moving speed of the copy paper.

Furthermore, when a jam occurs in the circuits shown in FIGS. 4 and 5, the relay 46 can simultaneously stop the operation of the entire copying machine. However, if the paper is fed with a delay, it is not preferable to immediately stop the drive of the conveyor belt at the same time as the jam signal. Therefore,
Additional safety is provided by providing a separate relay that deactivates the copying machine after the jam signal that activates the relay.

The above is an example of detecting a jam generated in the fixing device, but the present invention can also be applied to detecting a jam in the entire system from paper feeding to paper ejection. In that case, it is preferable to obtain a pulse signal equivalent to the conveyance distance in the present invention from the rotation of the carry-in roller 21 in FIG. 2 or a roller (not shown) that conveys the fed copy paper. A signal indicating the initial position of the distance can be generated in synchronization with the operation of the paper feed roller. Furthermore, the present invention is applicable not only to copying machines but also to devices in which objects such as paper are transported by a transport means such as a transport belt.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a color copying machine to which the present invention can be applied, FIG. 2 is a schematic diagram of a jam detection device in a fixing device, and FIG. 3 is a diagram showing an example of a circuit of a paper detection means.
Figure 4 is a diagram showing an example of the circuit of the jam detection device, Figure 5
The figure is a diagram showing another example of the circuit of the jam detection device.
The figure shows an example of a control circuit for a copying machine.
M is transport distance signal, PH-IN is entrance signal, PH-
EX is exit signal, 37 is flip-flop, 38
12 is a conveyor belt, 31 is a disk having a slit 33, and 20 is copy paper.

Claims (1)

[Claims for Utility Model Registration] A color image forming means for forming a color image on fed paper; a paper conveying means for conveying the paper on which the color image has been formed by the color image forming means; and the paper It has a fixing means for fixing the color image on the paper conveyed by the conveyance means, and a selection means for selecting the moving speed of the paper conveyance means, and the selection means fixes the color image formed on the paper. The moving speed of the paper conveying means is variable depending on whether the paper is of a single color or multicolor, and further includes a pulse generating means that generates repeated pulses in synchronization with the paper conveying operation of the paper conveying means, and specifying the paper conveyance path. and a determining means for determining whether or not the paper has normally arrived at the detecting means, and the determining means detects the detection output of the paper detecting means and the pulse generating means. A color image forming apparatus characterized in that it is configured to determine whether or not paper is being conveyed normally, based on the amount of pulses generated, regardless of the moving speed of the paper conveyance means by the selection means.