JPS5819485Y2 - slip detection circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention is a detection circuit for detecting whether or not a specified amount of roll film has been conveyed in a mechanism for conveying a roll film-like medium. This invention relates to a detection circuit for slips that can be a problem.

In a system that requires winding or feeding a roll of film, it is important to accurately specify the amount of transport.

An example of such a system will be described below using a phototypesetting apparatus.

Recent phototypesetting apparatuses use a computer or the like to display dot characters on a CRT, and then expose the dot characters onto a roll of photosensitive paper, shifting the dot characters, for example, in A4 size increments.

In this case, if the photosensitive paper is not conveyed accurately by the specified A4 size, the nth (n
= 1.2゜3...) A4 size photosensitive area, especially its bottom edge, and the n+1th A4 size photosensitive area, especially its top edge, do not match each other, and in the worst case, the photosensitive area on the photosensitive paper A problem arises in that two types of exposure are performed on the same part.

As will be described later, since this type of photosensitive paper is fed by a specified amount by friction with the capstan, slippage between the photosensitive paper and the capstan is inevitable.

This slip causes the worst problem mentioned above.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a snoop detection circuit that monitors whether the slip is below a minimum amount that is practically acceptable in order to prevent the worst problems described above from occurring. .

In accordance with the above object, the present invention has a winding capstan and a feed roller disposed at the leading edge (leading edge in the advancing direction of the photosensitive paper) and rear end of the printing surface on which predetermined dot characters are printed, and the winding capstan The first number of pulses supplied to the pulse motor that drives the feed roller and the second number of pulses sent out in proportion to the rotation of the feed roller are counted by first and second counters, and the number of these pulses is A comparison of the magnitudes of is monitored every time the photosensitive paper is fed, and further, a predetermined pulse is additionally supplied to the first or second counter until the results of the magnitude comparison match, and this additionally supplied predetermined pulse is The present invention is characterized in that it is detected whether the number of pulses is greater or less than a predetermined number.

The present invention will be explained below according to the drawings.

FIG. 1 is a diagram schematically illustrating the mechanism of a phototypesetting apparatus to which the present invention is applied.

In this figure, 11 is a band-shaped photosensitive paper (photosensitive film), and raw photosensitive paper 11 is fed from a hopper 12=1.
A predetermined character is photosensitive printed in the printing section 13, and the paper is taken up on the stacker 12-2.

The printing unit 13 includes a CRT 13-1 for displaying characters specified by the computer COM in a dot pattern, and a lens 13-2 for enlarging the characters to, for example, A4 size.

After printing for A4 size on the photosensitive paper 11, the photosensitive paper is wound up in the direction of arrow A and printing for the next A4 size is performed.

Therefore, these operations are performed intermittently.

This intermittent feeding in the direction of arrow A is performed by the winding capstan 14.
It is done accurately by

In the figure, reference numeral 15 denotes a pulse motor that rotates the capstan 14 by a prescribed amount, and is driven by a pulse drive circuit 16.

However, since the photosensitive paper 11 is fed by friction with the take-up capstan 14, slippage in this area is unavoidable, and even if the capstan 14 is driven in pulses accurately, the photosensitive paper 11 will not be exposed to light by an amount exactly proportional to this. It is extremely difficult to feed the paper 11 by an A4 size in the direction of arrow A.

Measures have been taken to suppress this slippage in the capstan 14 as much as possible, such as by adhering the photosensitive paper 11 to the capstan 14 using negative pressure air, but this is not perfect.

As a result, the above-mentioned problem of double exposure to the same portion of the photosensitive paper occurs.

Note that r in the drawings are all rollers, and in particular, br is a buffer roller that buffers the tension applied to the photosensitive paper.

Therefore, the present invention has the following configuration based on the idea that if there is no difference in the conveyance amount of the photosensitive paper 11 at least at the inlet IN and the outlet OUT of the printing section 13, the slip does not occur.

First, a slit plate 18 that rotates in synchronization with the feed roller 17 at the entrance IN of the printing section 13 is provided.

Further, sandwiching the slit plate 18, the photocoupler 19-1.1
9-2 will be provided.

The number of output pulses P1 from this photocoupler 19-2 is
Exactly proportional to the amount of photosensitive paper 11 being fed out of the population IN via rollers 17.

On the other hand, the number of output pulses P2 from the pulse drive circuit 16 is
It is approximately proportional to the amount by which the photosensitive paper 11 is wound up from the outlet OUT via the capstan 14.

Here, the reason why it is said that the ratio is approximately proportional is that the above-mentioned slip may occur in the capstan 14.

Assume now that the number of sending pulses P1 at the inlet IN exactly matches the number of winding pulses P2 at the outlet OUT.

In this case, it goes without saying that the photosensitive paper 11 slid over the printing section 13 by exactly the amount of A4 paper.

However, there are cases where the pulse numbers P1 and P2 do not exactly match.

This is not only caused by the above-mentioned slip in the capstan, but also due to various factors such as transmission delay of the photosensitive paper 11, play of the rollers, and play of the photosensitive paper.

However, based on these various factors, even if the photosensitive paper is not fed by an amount that completely matches the specified amount, a certain amount of deviation from the specified amount should actually be allowed.

It has been experimentally found that this deviation is sufficient as long as it is O0 several mm or less.

Therefore, the number of pulses corresponding to this allowable deviation is (
Assuming that P, there is no practical problem as long as 1P2-P11≦JP (1) holds between the pulses P1 and P2.

Note that since P2≧P1 usually holds between Pl and P2, the above formula (1) % formula % (2) is obtained.

In other words, find the difference between P2 and Pl, and if this is within P, you can continue the next printing operation, and this is the JP
If this is the case, it is necessary to make some kind of correction to the photosensitive paper feed and start the next printing operation.

FIG. 2 is a block diagram showing an example of a circuit for detecting whether the difference between P□ and P2 exceeds JP.

Generally, the occurrence of JP depends most heavily on the slip, so this is called a slip detection circuit.

In this figure, first, the first counter 21. The second counter II 22 and the counter 23 are reset by the photosensitive paper feed start command.

Thereafter, the pulse P1 from the photocoupler 19-2 is applied to the counter I 21, and the pulse P2 from the pulse drive circuit 16 is applied to the counter II 22, and each starts counting.

When one paper feed is completed, the counts of counters 21 and 22 are compared in comparator 24.

As a result of this comparison, if the comparator 24 outputs a positive pulse when the pulse count value is P2>PI, and outputs a negative pulse when P2<PI, for example, when P2>Pl, the comparator 24 outputs a positive pulse. is output, AND gate 25-1 is opened, and AND gate 25-2 is closed.

On the other hand, at this time, since a stop command indicating that one paper feed has been completed has been output, the AND gate 26 is opened, and the pulse p from the pulse generator 27 is output to the computer 25- 1 through and or gate 281
is applied to the first counter I 21 through the counter I 21 to accumulate its count value.

Note that the pulse p from the pulse generator 27 and the pulse P1 (and P2) have exactly the same period, pulse width, etc.

At the same time, the AND gate 29 is opened by the stop command indicating that the paper feeding has ended, and the pulse p is sent to the counter 23 only while the positive (or negative) comparison signal continues to be sent from the comparator 24. do.

Note that the gate circuit 30 is open only while a match cannot be achieved in the comparator 24, that is, while a positive or negative comparison signal is being sent out, and allows the pulse p to pass.

Now, when a paper feed stop command is issued, if the count values of the counters 21 and 22 are P2>Pi, a pulse p is sent out from the pulse generator 27 through the gates 26.25-1 and 28-1, and the counter Since the contents of 21 are counted up, when a certain appropriate number lp of pulses p is sent out, P2=P1+ip.

Comparator 24 sends out a coincidence signal (O level) for the first time at this time and closes gate circuit 30.

Therefore, the count value of the counter 23 is jp.

In other words, this Jp is the deviation from the specified amount that occurs during the eccentric paper feeding.

Here, the counter 23 can count up only up to JP shown in equations (1) and (2) above, that is, the number of pulses corresponding to the allowable deviation, so if JP > JP... (3) If so, the contents of the counter 23 will overflow and an alarm will be generated.

Then, from this alarm, the operator is informed that an unacceptable paper feed deviation has occurred, and the next printing operation is put on hold and appropriate measures are taken.

Alternatively, the pulse motor 15 is driven by the number of pulses corresponding to the overflow, and the paper is further fed through the capstan 14.

On the other hand, if yp≦JP (4), we know that the counter 23 did not overflow and the paper was fed normally within the allowable deviation.
Start the next printing operation.

As explained above, according to the present invention, the amount of movement of the photosensitive paper at the entrance and exit of the printing section 13 can always be matched within an allowable error range, and a high-quality paper feeding mechanism can be realized. This is generally suitable for transporting roll-shaped films with high precision.

[Brief explanation of drawings]

FIG. 1 is a diagram schematically illustrating the mechanism of a phototypesetting apparatus as an example to which the present invention is applied, and FIG. 2 is a block diagram showing an embodiment of a slip detection circuit based on the present invention. In the figure, 11 is photosensitive paper, 14 is a winding capstan, 16 is a pulse drive circuit, 17 is a feed roller, 18
is a slit plate, 19-1 and 19-2 are photocouplers, 2
1 and 22 are the first and second counters, and 23 is the third counter.
24 is a comparator, and 27 is a pulse generator.

Claims (1)

[Scope of Claim for Utility Model Registration] A feeding mechanism for a strip-shaped photosensitive film that exposes a strip-shaped photosensitive film while feeding it by a predetermined amount, including a take-up capstan that feeds the strip-shaped photosensitive film by a predetermined amount and a rotation of the take-up capstan. a motor; a feeding roller that rotates as the strip-shaped photosensitive film moves; and a first counter that counts a first pulse P1 from a rotation detection pulse generating means that sends out a pulse synchronized with the rotation of the feeding roller; A second counter that counts the second pulse P2 from the pulse drive means that drives the winding capstan is compared with the counted values of the first and second counters when one prescribed amount of feeding is completed. a comparator; and a pulse generator that supplies a third pulse p to the first or second counter, whichever has the smaller count value, after one prescribed amount of feeding is completed, until the contents of both counters match. and the number of the third pulses p supplied from the pulse generator after one prescribed amount of feeding is completed, (where P is an allowable error for one prescribed amount of feeding, compared to JP). A slip detection circuit that generates an alarm only when it detects that J p>, a p .