JPS6338703B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copying interval control device for controlling the copying interval in a copying machine capable of continuous copying.

[Conventional technology]

In electronic copying machines, heating is performed to fix toner on supplied paper, and the temperature of the rollers used for this purpose must be above a certain value.

However, when copying is performed continuously, the roller temperature may drop depending on conditions such as room temperature, changes in power supply voltage, and the type (thickness) of the transfer paper, so the roller temperature may drop to the constant value mentioned above. If the value is lower than that, you will not be able to expect high-quality copies. In extreme cases, there is a possibility that unfixed paper may be sent out.

For this reason, in the past, an electric heating device with a sufficiently large capacity (2 to 4 times the normal temperature) was prepared so that the roller temperature could be maintained within the fixing temperature range even under the worst conditions.
In addition, in order to prevent the temperature from dropping during paper passing, a separate electric heating device was provided that could be turned on only when paper was being passed.

FIG. 1 is a graph showing the relationship between the number of copies t and the roller temperature during continuous copying. During continuous copying, the roller temperature T increases as the number of copies t increases.
It is shown that the initial temperature T ₀ drops once to T ₁ , then rises a little and settles at T ₂ .

[Problem to be solved by the invention]

In this case, in order to be able to fix even if the temperature is T ₁ , it is necessary to have sufficient margin in the electric heating equipment and to adjust the initial temperature.
T ₀ must be set at a high temperature that sufficiently takes into account the amount of temperature drop (T ₀ −T ₁ ), which poses an obstacle in terms of safety and efficiency. Furthermore, depending on conditions such as abnormal voltage drop, the roller temperature may drop below the fixing limit temperature T _L as shown by the broken line, resulting in unfixed images. Reliability was essential for reliable copying. Moreover, since the capacity of electric heating equipment generally increases, especially for high-speed machines, general purpose outlets are rated at 100V/15A.
It was difficult to keep the total power down to below. Therefore, the electric power required for copying per sheet is large, which is not economical, and the power supply fluctuations at the start of copying are large, which is not desirable as a characteristic of a copying machine.

The present invention has been made in an attempt to eliminate the drawbacks of the prior art described above, and an object of the present invention is to provide a copying interval control device for a copying machine that can economically perform continuous copying at a temperature above a certain temperature.

[Means to solve the problem]

In order to achieve this object, the present invention provides a copying interval control device for controlling the copying interval of a copying machine capable of continuous copying, which includes a detection device that directly or indirectly detects the temperature of a heat-fixing roller. , a comparison device that has one reference value that is higher than the lower limit value of the fixing temperature and is set so that the roller temperature does not fall below the lower limit value of the fixing temperature during paper feeding, and compares this reference value with the output of the detection device. , a continuous copy control device that outputs a copy start preparation command based on the copy continuation command and the next copy cycle start command, and a logical product that forms a copy start command by the logical product of the output of the comparator and the copy start preparation command. The present invention is characterized in that when the detected roller temperature falls below a reference value, a copying start command is issued after waiting for the roller temperature to rise, and the next copying cycle is executed.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a block diagram showing one embodiment of the present invention.

According to the figure, a temperature detection device 20 is provided that detects the surface temperature of the roller based on a signal from a temperature sensor such as a thermistor, and this temperature detection device 20 directly detects the temperature of the roller. be able to. In some cases, a temperature detection device may be used that indirectly calculates and detects the roller temperature by detecting the temperature and thickness of the transfer paper, or the drop value of the power supply voltage.

The temperature detected by such a temperature detection device 20 is compared with a reference value T _S in a comparator circuit 21. Reference value
If T _S or more, a fixing enable command Sa is given.
This standard value T _S is the lower limit value T _L of the roller temperature during paper feeding.
The value is set higher than the lower limit T _L so as not to be below. The reference value T _S is set with safety in mind since the roller temperature may drop during execution of the copying cycle.

On the other hand, a continuous copy control device 23 for performing continuous copying is provided. This continuous copying control device 2
3 is a copying continuation command A that is issued when the specified number of consecutive copies has not been completed, and a copying cycle start command B that allows the transition to the next copying cycle after the previous copying cycle has finished. A copy start preparation command Sb is given to indicate that preparations are complete for starting the copy cycle.

These comparison circuits 21 and continuous copying control device 23
The output is sent to the copy command device 2 via an AND circuit 22.
given to 4. Therefore, even if copying is ready and the device 23 is giving the output Sb, if the roller temperature is below the reference value T _S , the comparator circuit 21 will not send a signal, and therefore the AND condition of the AND circuit 22 will not be satisfied. Not satisfied. Similarly, the roller temperature is the standard value T _S
As described above, even if the fixing is possible, the AND condition of the AND circuit 22 is not satisfied unless preparations for continuous copying are completed. Therefore, the AND condition of the AND circuit 22 is satisfied only when the fixing enable command Sa is given by the comparator circuit 21 and the copy preparation command Sb is given simultaneously by the continuous copying control device 23. After that, a copy start command C is issued. This copy start command C is sent to a paper feeding device, for example, and instructs the start of paper feeding. This copy command device 24 may include various circuits, but without using any of these, the output of the AND circuit 22 is directly transmitted to the copy start command C.
It may also be used as

FIG. 4 is a sectional view showing the structure of a heat fixing section in a copying apparatus to which the present invention is applied.

Rollers R1 and R2, each having heaters H1 and H2 inside, are configured to rotate in circumscribed contact with each other, and the developed paper P is driven in the Q direction and passes between these rollers, The image is fixed by being heated.

A temperature sensor D is lightly pressed against the surface of the upper roller R1 by a leaf spring S, and this temperature sensor D detects the surface temperature of the roller R1. Oil such as silicone is placed above roller R1.
OL is stored, and this oil is guided to the oil application roller OR by a guide member G such as felt, and the oil is applied to the roller R1. Further, the cleaning roller CR is in circumscribed contact with the roller R1, and is configured to clean the surface of the roller R1. The output of sensor D is the temperature detection device 20
is input.

FIG. 3 is a graph showing the operation of the copy interval control device according to the present invention. As shown in Figure 3a,
If the roller temperature gradually decreases from the initial temperature T ₀ but remains above the reference value T _S , continuous copying is performed as shown in Figure 3b, but if the roller temperature is higher than the lower limit of fixing temperature T _L When the roller temperature falls below a predetermined set reference value T _S , continuous copying is not performed and the roller temperature enters a standby state, and a copy start command is given only when the roller temperature has recovered to the reference value T _S or higher. Third
The figure shows that even when the roller temperature decreases again due to copying after the roller temperature has recovered to the reference value T _S or higher, the printer enters the standby state again.

5 and 6 are timing charts showing detailed operations of the copy interval control device according to the present invention.

Figure 5 shows normal continuous copying operation. Since the roller temperature signal is high because the roller temperature is higher than the reference value, feeding from the tray is performed by pressing the print switch. The paper is exposed and then the scanner is moved to expose and return, and the exposure forms a latent image on the photoreceptor. The fed paper is stopped in front of the photoreceptor, and when the dew hole advances to a predetermined position, the direction of the photoreceptor is advanced and transfer is performed. Thereafter, fixing is performed using a known method. In the figure, the roller temperature signal is high after the first copy cycle is completed, and the roller temperature has not decreased, so the AND condition of the signals Sa and Sb is satisfied.
A second copy cycle is performed in succession.

On the other hand, FIG. 6 shows continuous copying operation when the roller temperature decreases, and in this case, 1
Since the roller temperature has decreased after the first copy cycle is completed, the second copy cycle is not executed and remains in standby mode, and the roller temperature recovers and becomes higher than the set temperature, causing the roller temperature signal to rise. As soon as the signal goes high, feeding of the second sheet starts. Thus, by comparing FIG. 5 and FIG. 6, it can be seen that in the case of FIG. 6, the copying of the second sheet is delayed until the roller temperature recovers.

〔Effect of the invention〕

As described above, according to the present invention, when the temperature of the heating roller of the fixing section drops during continuous copying, the next copying cycle is started on the condition that the temperature has recovered to a certain value or higher. This makes it possible to prevent poor fixing by taking into consideration the thermal responsiveness of the rollers and thermistor, without causing the interruption of copying during continuous copying, and to ensure high-quality copying. Furthermore, since the capacity of the heating device can be reduced, economic efficiency is improved, and a simple copying machine that can be used even with a normal electrical outlet can be provided.

[Brief explanation of the drawing]

Fig. 1 is a graph showing changes in roller temperature according to the conventional method, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is an explanation showing the operation when using the device shown in Fig. 2. 4 are sectional views showing a schematic configuration of a copying apparatus to which the present invention is applied, and FIGS. 5 and 6 are timing charts showing the operation of the present invention in further detail. 20...Temperature detection device, 21...Comparison device, 2
2...AND circuit, 23...Continuous copying control device,
24...Copy command device.

Claims (1)

[Scope of Claims] 1. In a copying interval control device that controls the copying interval of a copying machine capable of continuous copying that continuously executes copying cycles for a specified number of sheets, the temperature of a heat-fixing roller is directly or It has a detection device that performs indirect detection, and a reference value that is set higher than the lower limit value of the fixing temperature so that the roller temperature does not fall below the lower limit value of the fixing temperature when the paper passes, and this reference value and the output of the detection device a comparison device that compares the output of the comparison device with the copy start preparation command based on the copy continuation command and the next copy cycle start command; and an AND circuit for forming a copy start command, and when the detected roller temperature falls below the reference value, waits for the roller temperature to rise and then issues the copy start command to execute the next copy cycle. A copying interval control device.