JPS58211478A - Form feed controlling system - Google Patents

Abstract

PURPOSE:To make possible prevention of slipped printing of a cut form by controlling the rotary speed of the timing roller to correct a deviation between the reference time and a time to detect the edge of a feeding cut form by the form detecting means. CONSTITUTION:A cut form fed by the feeding roller 1 strikes the timing roller 4, stops once, trues up the edge and then is fed by the revolution of the timing roller 4 for the printing position 21 on the printing drum 12. When the edge of the form is detected by the form detector 5 an SHTTOP signal is generated. This signal is inputted into the deviation detecting circuit 14 with the TOP signal nearly at the same time with the standard rise time of the SHTTOP signal generated from the controlling means, changes the oscillating frequency of the variable frequency oscillator 16 according to deviations between the feeding speeds of forms and controls the number of revolution of the timing roller 4 through the motor driving circuit 16, the motor 17. In this manner, the cut form can be prevented from slipped printing.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a paper conveyance mechanism of a printing apparatus that uses cut paper, and particularly relates to a paper conveyance control system for preventing printing misalignment of cut paper.

Prior Art When printing on cut paper, especially preprinted cut paper, printing misalignment must be strictly prevented. Therefore, in printing devices such as drum-type electrophotographic printers that use cut paper, the cut paper fed to the conveyance path is temporarily stopped by a timing roller on the conveyance path, the leading edge of the cut paper is aligned, and then the timing roller A paper conveyance mechanism configured to rotate the paper and convey the cut paper to the printing position is used. However, even with such a configuration, it is about 1/100
The reality is that a printing misalignment of 2rrf11s occurs at a rate of 0 sheets, and there is an inconvenience in that an operator has to visually check for printing misalignment when printing preprint cut sheets.

OBJECTS OF THE INVENTION An object of the present invention is to provide a paper conveyance control system for automatically preventing the above-mentioned printing misalignment.

According to the present invention, the cut sheets are fed one by one to the conveyance path, the cut sheets are temporarily stopped by the timing roller on the conveyance path, and the leading edges of the cut sheets are aligned, and then the timing roller is rotated. In a paper conveyance mechanism of a printing device configured to convey the cut paper to a printing position by a paper detecting means, a paper detecting means is provided between the timing roller on the conveying path and the printing device, and the paper detecting means A means for detecting the deviation between the time at which the leading edge of the cut paper is detected during transportation and its reference time, and a means for detecting the deviation between the time at which the leading edge of the cut paper is detected during transportation and its reference time, and a means for detecting the deviation until the leading edge of the cut paper reaches the printing position so as to correct the deviation detected by this means. means for controlling the rotational speed of the timing roller during the period.

Embodiment of the Invention An embodiment of the present invention will be described with reference to FIGS. 1 to 4.

(3) FIG. 1 is a side view schematically showing the main mechanical parts of a drum-type electrophotographic printing apparatus according to the present invention.

The cut sheets 2 are stacked and stored in the cassette 8 yen. The paper feed roller 1 rotates counterclockwise in the figure while contacting the surface of the uppermost cut paper 2 in the cassette 8, and feeds the cut paper into a conveyance path consisting of a pair of guide plates 6. . The feeding roller 1 can be moved up and down (two times) by a mechanism not shown, and is lowered during feeding.

A pair (or two or more pairs) of upper and lower timing rollers 4 are disposed in the middle of the conveyance path. The cut paper fed by the feeding roller 1 collides with the timing roller 4 and stops once, and the leading edges are aligned.

Thereafter, a motor (not shown) is activated to rotate the timing roller 4, and the cut sheet is sandwiched by the timing roller 4 and guided along the conveyance path to a specific position on the print drum 12 &(
The paper is transported toward the print position (printing position) 21.

The printing drum 12 rotates clockwise in the figure and receives an image recording beam (image (4)) from the direction indicated by an arrow 13.
- The electrostatic latent image of an image such as a character is scanned by a light beam modulated by data), and the electrostatic latent image of an image such as a character on the surface is visualized by toner adhesion when passing through the phenomenon device 11. Therefore, at the printing position 21, the visualized image is transferred to the cut sheet.

The cut sheet on which the image has been transferred is separated from the printing drum 12 by a separation roller 7, and is ejected to a tray 10f via a fixing device 8 and an ejection roller 9. Therefore, the route through which the cut paper is discharged is as shown by the arrows.

Also on the conveyance path are a timing roller 4 and a printing position 1ii.
A paper detector 5 is provided between the paper detector 21 and the paper detector 5 .

This paper detector 5 is, for example, a known optical sensor.
When the leading edge of the cut paper passes directly under it, the output signal ``I''
It is inverted from the O'' level to the '1'' level.

As will be described later, the delay or advance of the cut paper is corrected during the period when the cut paper passes between the paper detector 5 and the print position, so the distance from the paper detector 5 to the print position 21 is adjusted accordingly. Determined to be sufficiently strong.

The general operation of this embodiment will be explained with reference to the timing diagram of FIG.

When a TOP signal is output from a control unit (not shown) of the printing apparatus, irradiation of the image recording beam starts after a certain period of time. After a TQ waiting time after the TOP signal is generated, the paper feed roller 1 descends and rotates to start the paper feeding operation), and at the same time, the timing roller 4 stops.

Seventeen hours after the TOP signal is output (the leading edge of the fed cut paper collides with the timing roller 4 and the leading edge alignment is completed), the timing roller 4 starts rotating. When the leading edge of the cut paper advances to just below the paper detector 5, the SHT'rop signal output from the paper detector 5 changes from the "0" level to the 1' level.

When the cut paper reaches its full capacity, the SHT TUP signal rises after TPs time (reference time) from the rotation start time of the timing roller 5. If the conveyance is shifted to the n side, the SHT T OP signal is
) stand up after. (If the cut paper is conveyed with a shift in the opposite direction, TP2<TPs.) If the timing roller 4 continues to rotate at a constant speed regardless of the delay or advance in the conveyance of the cut paper , there is a difference in the time at which the leading edge of the cut paper reaches the printing position 21 (second position), and as a result, printing misalignment occurs.

According to the present invention, in order to prevent such printing misalignment, the timing roller 40 rotational speed is adjusted during the period until the leading edge of the cut paper moves from the paper detector 5 to the printing position (double printing position) to prevent printing misalignment. An example of control for performing a correction operation is shown in FIG. 8 and will be described.

17 is a motor that rotationally drives the timing roller 4. Reference numeral 15 denotes a variable frequency oscillator with a variable frequency in eight stages (two variables), and its output signal is input to a motor drive circuit 16. The motor drive circuit 16 rotates the motor 17 at a rotation speed proportional to the frequency of the input signal. .

14 is a deviation detection circuit, which detects the TOP signal and 5HTTOP.
With the signal as input, the deviation ΔT=TPs−TP2 of the generation time of the 5HTTOP signal is detected. Then, when ΔT=Q, a reference speed signal is outputted, and when ΔT(Q), a high speed signal is outputted, and △1゛〉0
When , a low speed signal is output. The output power of the high speed signal and the low speed improvement () is determined depending on the first shift of 1△T1, and after that time, the reference speed signal is output. After T01 time has elapsed, the time when the deviation Δ1゛ is not detected (S H'r 'r a l)
(The rising time of fk and fk are the same) Therefore, the deviation detection circuit 14 has a reference speed signal full output of 1.

The variable frequency oscillator 15 oscillates at the standard frequency while the reference speed signal is input manually, oscillates at a round frequency - while the high speed signal is input, and oscillates at a round frequency - while the low speed signal is input. Oscillates at a low frequency. However, there is a relationship of fingers>fN>fL.

FIG. 4 shows changes in the rotational speed of the timing roller 4 when the deviation ΔT is negative and the reload paper can be transported.

As shown in the figure, the rotational speed of the timing roller 4 is 1Δ
The deviation ΔT is corrected by increasing the cylinder speed by a time corresponding to the value of 1, and the leading edge of the cut paper becomes Δ'r.
The printing position [21 (FIG. 1) is reached at the same time as in the case of -0. Therefore, printing misalignment is prevented.

On the other hand, if the deviation ΔT is positive and the conveyance of the tightly cut paper progresses, the shift is switched to the low speed variation for a period of time related to the value of 1ΔT1, as shown in FIG.

In this way, the deviation △T is corrected, and the leading edge of the cut paper is
The printing position 21 is reached at the same time as in the case of T=Q, and no printing deviation occurs.

Note that in Figures 4 and 5, rice is at the standard speed. V
N and VH2■L are in a proportional relationship with fN, fH, and fL, respectively.

Although one embodiment has been described, it goes without saying that the present invention can be modified in various ways. For example, variable frequency oscillator 15
The frequency of ΔT ”q can be varied in multiple stages or continuously.
In the case of o, it is also possible to oscillate by switching to a frequency corresponding to the value of 1Δ1゛1 for a certain period of time. in this case,
The deviation detection circuit 14 detects 1ΔT1 and ΔT when ΔT)0.
It is possible to output a signal indicating the sign of 1ΔTl for a certain period of time regardless of the value of 1ΔTl.

It goes without saying that the present invention is not limited to the rotary drum type electrophotographic printer, but can be similarly applied to other types of printing devices.

Effects of the Invention As detailed above, according to the present invention, it is possible to prevent printing misalignment on cut paper, so that pre-printing is possible.

It is possible to realize a high-performance printing device that does not require visual confirmation of printing misalignment on cut paper.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view showing only the lower part of an example of a printing device according to the present invention, Fig. 2 is a timing diagram for explaining the operation of the printing device, and Fig. 8 is a control system for correcting printing misalignment. FIGS. 4 and 5 are block diagrams showing an example of the timing roller speed control. DESCRIPTION OF SYMBOLS 1... Paper feed roller, 2... Cut paper, 4... Timing roller, 5... Paper detector, 6... Guide plate forming a conveyance path, 14... Deviation detection circuit, 15・
...Variable frequency oscillator, 16...Motor drive circuit, 1
7...Motor, 21...Printing position. /r゛. Figure 1a Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] (1) Feed the cut sheets one by one to the conveyance path, temporarily stop the cut sheets with the timing roller on the conveyance path to align the leading edges of the cut sheets, and then cut the sheets by rotating the timing roller. In a paper transport mechanism of a printing device configured to transport paper to a printing position, a paper detection means is provided between the timing roller on the transport path and the printing position, and the paper detection means detects cuts during transport. means for detecting the deviation between the time when the leading edge of the paper is detected and its reference time; and the above-mentioned timing in the period until the leading edge of the cut paper reaches the printing position so as to correct the deviation detected by this means. 1. A paper conveyance control system comprising means for controlling the rotational speed of a roller.