JPS646034B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a perforation hole pulse, that is, a homepage, at approximately the center of a perforation signal generated each time perforation holes provided at predetermined intervals along both edges of a continuous slip sheet in the feeding direction are detected. This invention relates to a perforation pulse generator for continuous slips that generates pulses.

FIG. 1 schematically shows a fixing section of a printer employing an electrophotographic method. A certain range on both sides of the folding perforation of the paper 4, for example, a range of 8.5 mm from the perforation, is not printed, and this part is referred to as a printing prohibited area. The toner attached to the paper 4 is removed from the preheater 1.
The image is heated by the heat roller 2 and the backup roller 3 and fixed. When printing stops, the paper 4 in the fixing section also stops, but only the print-prohibited area must come into contact with the heat roller 2 so that the toner on the paper 4 does not adhere to the heat roller 2 when printing stops. Assuming that the contact width between the heat roller 2 and the back-up roller 3 (the length in the feeding direction of the paper 4) is, for example, 12 mm, and the print-prohibited area is 8.5 mm on both sides of the perforation, when the printer stops The error in the perforation position must be less than 5 mm.

In order to detect the travel distance of the paper 4 fed out by the heat roller 2, the paper 4 is
A perforation hole detector is provided at a portion through which perforations provided at predetermined intervals pass along both edges in the feed direction. The diameter of the feed hole is 4 mm.

Figure 2 shows the sprocket hole detector, Figure 3 shows the detector output.
Shown in l ₀ (sprocket hole signal). When the perforation hole 7 faces the detector section and the light from the light emitting diode 5 is not reflected by the paper 4, no current flows through the phototransistor 6, and the perforation hole signal _l0 has a logic value of 0. When paper 4 is present, the sprocket hole signal _l0 has a logical value of 1. The feed holes are drilled every 12.7 mm (0.5 inch), and by counting the feed hole signal _l0 , the travel distance of the paper 4 fed out from the heat roller 2 can be determined.

When the paper 4 stops, there are restrictions as described above, but in order to control the stopping position of the paper 4 in this way, a pulse is generated at the trailing edge of the sprocket hole signal _l0 (point A in Figure 3) (when the sprocket hole This pulse generated from the signal _l0 is hereinafter referred to as a home pulse), and deceleration starts based on the position where this home pulse is generated, and the perforation stops at the center of the contact area between the heat roller 2 and the backup roller 3. It is controlled as follows.

However, in this case, when the paper 4 moves obliquely on the preheater 1, the pulse width of the perforation signal _l0 changes, and the position where the home pulse is generated is also shifted. That is, the light emitting diode 5
As shown in the figure, the center of the sprocket hole is irradiated, but as the paper 4 is skewed, the position of the sprocket hole 7 and the light emitting diode 5 is shifted, the pulse width of the sprocket hole signal changes, and the home pulse The location of the occurrence is incorrect.
If the occurrence position shifts and the reference position is out of order, the perforation stop position will also shift.Since the diameter of the sprocket hole 7 is 4 mm, if the center is set to 0, the reference position will be adjusted to a maximum of ±2 mm due to skew. You'll go crazy. As a result, the perforation cannot stop at the center of the contact area between the heat roller 2 and the backup roller 3.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to generate a home pulse at a substantially constant position even when the pulse width of the sprocket hole signal changes due to skewing of paper, thereby preventing deviations in the reference position. The objective is to reduce the paper stop position and thereby improve the accuracy of the paper stop position.

The present invention focuses on the fact that since the paper's sprocket holes are provided at a short pitch, the pulse widths of adjacent sprocket hole signals are almost the same even if the paper is skewed, and the pulse width of the sprocket hole signals detected from now on is The generation timing of the home pulse is determined according to the pulse width of the previous perforation hole signal. The center of the sprocket hole signal almost does not move regardless of the pulse width, that is, even when moving diagonally,
By generating the home pulse near the center of the perforation signal, the reference position can be kept almost constant regardless of skew.

FIG. 4 shows a view of FIG. 1 viewed from the direction of the arrow.
In FIG. 4, reference numeral 9 denotes a perforation detector consisting of the light emitting diode 5 and phototransistor 6;
0 and 11 are gears, 12 is a motor that drives the heat roller 2, and 13 is an encoder attached to the motor 12. Assume that the number of pulses of the encoder 13 is 240 per revolution of the motor shaft, and that the paper 4 is fed out from the heat roller 2 by 50.8 mm per revolution of the motor shaft (an error occurs due to variations in the diameter of the heat roller 2, etc.). do. Therefore, the paper 4 is advanced by approximately 0.21 mm per encoder pulse. Since the travel distance of the paper 4 is considered to be determined by the amount of rotation of the heat roller 2, the pulse width of the perforation signal can be determined by counting the encoder pulses generated during the generation of the perforation signal. Further, the interval between the sprocket holes 7 is 12.7 mm as described above, and it is considered that the skew of the paper 4 during this interval is small, and the pulse widths of adjacent sprocket hole signals are almost equal. Even if the pulse width of the sprocket hole signal changes due to skew feeding, the center position of the sprocket hole signal remains almost constant, so if the hole pulse is generated at the center position regardless of the speed of the paper 4, the standard The position will be kept constant regardless of the skew.

In FIG. 3, P ₀ is the already detected perforation signal, and the number of encoder pulses counted in P ₀ is n ₀ . The home pulse of the perforation hole signal _P1 is generated when encoder pulses are counted and stopped from the leading edge of the perforation hole signal _P1 , and N pulses are counted. The value of N shall be selected as shown in FIG. 5 according to the value of n ₀ . If the relationship between n ₀ and N is determined in this manner, the error of the home pulse generation position from the center position of the perforation hole signal will be as shown in FIG. For example, if n ₀ = 15, N = 7, and the error from the center position of the home pulse generation position is 0.5 (=
15/2-7)×0.21=0.105mm. every n ₀
In contrast, the maximum error amount of the home pulse generation position from the center position is 1×0.21=0.21 mm. This is approximately 1/9.5 of the conventional value. In FIG. 6, the + and - sides indicate that the home pulse is generated later and faster than the center position, respectively.

Next, a specific circuit will be explained with reference to FIGS. 7 and 8. 14 is a counter for counting encoder pulses, and 15 is a latch, which takes in the output of the counter 14 and temporarily stores it in response to the signal a shown in FIG. 16 is a ROM and n ₀ according to FIG.
The value of N for that is written. 17 is a counter, and the ROM 16 is controlled by the signal c shown in FIG.
The output of the encoder is subtracted by the encoder pulse. A zero pulse circuit 18 generates one pulse, that is, a home pulse, when the count value of the counter 17 is subtracted by the encoder pulse and becomes zero.

According to the present invention, even when the paper is skewed, the error in the home pulse generation position can be reduced, so that the accuracy of the paper stop position can be improved.

In the above embodiment, the value of N is divided into five stages, but if the error is allowed to be even larger, it may be divided into three stages, for example, as shown by x-x in Fig. 5. Maximum error is 1.5×0.21=0.315mm
becomes. Furthermore, the number of motor encoder pulses does not need to be 240 per rotation, and the value may be arbitrary as long as the required accuracy is selected.

[Brief explanation of drawings]

Fig. 1 is a side view schematically showing the fixing device, Fig. 2 is a schematic diagram of the sprocket hole detector, Fig. 3 is a time chart showing the relationship between conventional detector output and home pulse, and Fig. 4 is a schematic diagram of the sprocket hole detector. 1, FIG. 5 is a graph showing the relationship between n ₀ and N, FIG. 6 is a graph showing the error from the center position with respect to n ₀ , and FIG. 7 is an embodiment of the present invention. The block diagram, FIG. 8, is a time chart for explaining the operation of FIG. In the figure, 1 is a preheater, 2 is a heat roller, 3 is a backup roller, 4 is paper, 5 is a light emission time chart, 6 is a phototransistor, and 7
is a sprocket hole, 8 is a resistor, 9 is a sprocket hole detector, 10,
11 is a gear, 12 is a motor, 13 is an encoder,
14 and 17 are counters, 15 is a latch, and 16 is a
ROM 18 is a zero pulse circuit.

Claims (1)

[Claims] 1. At approximately the center of the perforation hole signal detected at predetermined intervals along both edges in the feeding direction of continuous slip paper sent by a roller driven by a motor with an encoder, A perforation hole pulse generator that generates perforation hole pulses, the perforation hole pulse generator comprising: a first counter that counts encoder pulses generated from the encoder during generation of the perforation hole signal when the perforation hole is detected; and a counter of the first counter. a storage means for generating a predetermined value N corresponding to a numerical value; and a storage means for counting encoder pulses generated from the encoder during generation of a perforation hole signal when the next perforation hole is detected; 1. A perforation pulse generator for continuous slips, comprising a second counter that generates pulses. 2. The perforation pulse generator for continuous slips according to claim 1, wherein the predetermined value N is approximately half the number of encoder pulses counted by the first counter. 3. The continuous slip perforation pulse generator according to claim 1, wherein the means for storing the predetermined value N is a ROM.