JPS6031142B2 - Document movement failure detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a device for detecting document movement disturbances, particularly for detecting document movement disturbances (hereinafter referred to as jams) in facsimile transmission systems, pattern recognition devices, code reading devices, copying machines, etc.
This invention relates to a document movement failure detection device that uses electronic circuit means to detect a problem in which the scanning signal remains the same for more than a predetermined number of scan lines when a jam occurs while scanning the document. It is.

Conventionally, in the above-mentioned facsimile transmission system and the like, a so-called mechanical means using a microswitch or the like has been used as a jam detection means in a graphic information/electrical information converter that scans a document while moving it.

In other words, at least two microswitches are placed one behind the other in the document movement area, and when the first stage microswitch detects the passing of the original but the second stage microswitch does not detect the passage of the original, a jam occurs. I try to regard it as such. In this case, especially in facsimile transmission, the paper thickness of the original document varies, and in the case of a thin original, the microswitch may actually cause a jam. In addition, there may be restrictions regarding the location of the microswitches and the like. The present invention aims to solve the above-mentioned problems, and aims to detect the occurrence of the jam using electronic circuit means. For this reason, the document movement failure detection device of the present invention is provided in a document transport device that is provided with a means for scanning a document in accordance with the movement of the document. a scanning line comparison circuit section that detects whether the two lines are in a matching state or a mismatching state within a predetermined condition range, and a mismatching state output that counts the number of scanning lines and outputs a mismatching state from the scanning line comparing circuit section. The present invention is characterized in that it is provided with a scanning line counting circuit section that is reset by the scanning line counting circuit section, and is configured to detect a movement disturbance of the document when the content of the scanning line counting circuit section exceeds a predetermined number of scanning lines. This will be explained below with reference to the drawings. The figure shows the configuration of an embodiment of the present invention.

The symbol *PENABLE in the figure is a page enable signal, which is a logic "1" signal when there is no document on the transport device, and VCL is a video clock signal, which is the same clock as the scanning clock that scans the document. LINE ENABLE is a scanning line signal, for example, a signal that is set to logic "1" at the beginning or end of each scanning line, and VIDEO is a scanning signal, which contains graphic information on the scanning line that scans the document. JAMRESET is a jam reset signal that is issued when the operator confirms that a jam has occurred.
JAMDET is a jam occurrence alarm signal, 1 is a scanning line comparison circuit section, 2 is a scanning line counting circuit section, 3 is a jam occurrence flip-flop, and 4 is a delay circuit for one scanning line (or a memory circuit that is delayed and 5 is a bit comparison circuit, 6 is a continuous mismatch counter, 7 is a flip-flop for detecting a predetermined condition, and 8 and 9 are scanning line counters, each of which corresponds to one page of the original. 10 and 16 represent NAND circuits, and 17 represents a NOR circuit, respectively, which can be counted. The document movement failure detection device according to the present invention is based on the following algorithm to detect the occurrence of a jam.

That is, under the condition where a wind jam occurs, the scanning signals that occur before and after each other should become the same signal.

However, the two scanning signals mentioned above do not necessarily match exactly.
Matching states and mismatching states are often repeated within a range of 3 to 3 bits.

Therefore, when both scanning signals do not appear consecutively for a predetermined bit length, for example, 7 bits or more, it is assumed that both scanning signals match. [C} As shown in 'B' above, it is assumed that there is no mismatch state for 7 or more consecutive bits in one scanning line, and then
By counting the number of scanning lines that appear continuously, a jam occurrence state can be detected.

{Success) However, if the original is completely blank or has only vertical lines, there will be no jam even though there is no jam.

The above situation (C) occurs. It is unthinkable that the situation like 'E- above m} continues for more than one page of the manuscript, for example, two pages.

If the above-mentioned factors {E} are considered, the occurrence of a jam should be detected correctly, and the diagram is constructed taking the above-mentioned factors into consideration.

That is, the '1} scanning signal is delayed by one scanning line by the delay circuit 4, and compared with the scanning signal by the bit comparison circuit 5.

■ When the bit comparison circuit 5 detects a mismatch, the reset for the continuous mismatch bit counter 6 is released;
The number of scanning clocks VCL during this period is counted.

That is, the number of consecutive mismatches is counted. {3}
During the scanning period corresponding to one scanning line, when the contents of the consecutive mismatched bits counter 6 reaches the value "7",
A predetermined condition detection flip signal is detected via NAND circuits 13 and 14.
Flop 7 is set.

The fact that the flip-flop 7 is set means that the document is moving correctly. '4) As a result,
Scan line counters 8, 9 are reset.

Since the flip-flop 7 is reset the next time the scanning line signal LINEENABLE appears, the scanning line counters 8 and 9 are reset to the scanning line signal until the flip-flop 7 is set. Count the number of LINEENABLEs. However, the scanning line counter 9 may be considered to perform counting after the scanning line counter 8 has been counted up. {5} As described in (3') above, when the original is moving correctly, the predetermined condition detection flip-flop 7 will never be in a state where it is not set at all.

That is, if a predetermined number of scanning lines are scanned, it will definitely be set once. (6}
How to determine the predetermined number of scanning lines is determined by considering various conditions, but in the case shown in the figure, the number of scanning lines corresponding to two pages of the original is determined by taking into account the case where the original is blank. When the counters 8, 9 are not reset during the number of lines, the counter 9 is made to issue a count up output.

When counter 9 issues a count-up output, in response to the next scan line signal LINE ENABLE,
Jam occurrence flip-flop 3 is set.

That is, the jam occurrence alarm signal JAMDET. is emitted.
As explained above, according to the present invention, if a means is provided to scan the original in response to the movement of the original, scanning signals can be compared between a plurality of scanning lines when the original is moving correctly. Taking note of the fact that they should be different from each other, the occurrence of a jam is detected using an electronic circuit.

Since the continuous mismatch counter 6 and the scanning line counters 8 and 9 are used, there is no possibility that a jam will be mistakenly assumed to have occurred. Particularly, when used for jam detection in a facsimile transmission system, a storage device is provided for band compression from the subordinate side, and this storage device can be used as is as the delay circuit 4 shown in the figure.

Furthermore, since the scanning line counting circuit unit 2 counts the number of scanning lines, it has the advantage that even if the scanning speed changes due to the presence of blank areas on the document during facsimile transmission, it will not be affected by this. have.

[Brief explanation of the drawing]

The figure shows the configuration of an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. In a document transport device provided with means for scanning a document in response to movement of the document, a scan signal of at least one scan line before and a scan signal of the scan line are compared. a scanning line comparison circuit section that detects whether the scanning line is in a matching state or a mismatching state within a predetermined condition range; What is claimed is: 1. A document movement failure detection device comprising: a scanning line counting circuit unit configured to detect a movement failure of the document when the content of the scanning line counting circuit unit exceeds a predetermined number of scanning lines; 2. The scanning line comparison circuit section includes a bit comparison circuit that compares the scanning signal of at least one scanning line before the scanning signal of the scanning line in a bit-by-bit manner, and detects the coincidence state or mismatch from the bit comparison circuit. 2. The document movement failure detection device according to claim 1, further comprising a counting circuit for counting the number of bits in which the state continues. 3. The counting circuit for counting the number of bits is configured to issue an output signal when the content reaches a predetermined value, and use the output signal to set or reset a flip-flop for detecting a predetermined condition. An apparatus for detecting an obstacle in document movement according to claim 2. 4. Claims 1 to 4, wherein the scanning line counting circuit section generates an output when its content reaches a value exceeding the number of scanning lines corresponding to at least one page of the original document. The document movement failure detection device according to any one of Item 3. 5. A patent characterized in that the scanning line counting circuit section is configured such that the count content is cleared by the output from the scanning line comparison circuit section or counting is permitted by the output. A document movement obstacle detection device according to claim 4.