JPH0310992B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention enables marks written on a mark sheet created according to a predetermined format to be
The present invention relates to a mark reading device that is read by a scanning type optical reading device such as a facsimile device.

2. Description of the Related Art Normally, in this type of mark reading system, mark sheets 1 and 2 as shown in FIGS. 1 and 2 are sequentially read by a reading device, and the resulting images are Based on the signals, first the start reference mark 3 in FIG. 1, the start reference mark 4 and the stop reference mark 5 in FIG. 2 are detected. Then, based on these detected positions, it is determined which section of one scanning line corresponds to each mark entry field 6, 7 (on mark sheets 1, 2, mark entry fields 6, 7
are in a predetermined positional relationship with reference marks 3, 4, and 5), and by referring to the image signal of the determined section, it is possible to determine whether or not a mark has been written in each mark entry field 6, 7. Determine.

Here, the scanning line referred to in the determination is only the scanning line in which the reference mark is detected.
Therefore, conventionally, in the case of the mark sheet 1 shown in FIG. 1, the determination has been made with reference to the image signal of the scanning line in which the start reference mark 3 was detected. In addition, in the case of mark sheet 2 in Figure 2,
Normally, the above-mentioned determination is made with reference to the image signal of the scanning line in which both the start reference mark 4 and the stop reference mark 5 are detected at the same time.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, in a reading device such as a facsimile machine, the mark sheet may be read in an inclined state compared to the normal state, and the number of scanning lines to be referred to in the above judgment is This has caused a problem in that the reliability of the reading results is significantly reduced.

One possible method of compensating for the decrease in reliability caused by the tilt of the mark sheet is to make the mark entry field sufficiently long in the sub-scanning direction, but in such a case, the efficiency of mark entry will be significantly reduced. However, this is not practical because it reduces the information density of the mark sheet.

Alternatively, as shown in FIG. 3, a tilt detection mark 14 is provided at the beginning of the mark sheet 13, and this tilt detection mark 14 allows
The inclination angle and direction of the mark sheet 13 have been detected in advance, and when determining whether or not a mark has been entered in the mark entry field, the left half of the mark sheet 13 is detected based on the detected inclination angle and direction. Conventionally, a method of switching the scanning line to be referred to (referring to another scanning line) between the right half and the right half has also been used.

However, in reading devices such as facsimile machines, the mark sheet rotates slightly as it travels, so the inclination angle of the mark sheet may change from the start of reading to the end of reading. However, there was a drawback that the above-mentioned decrease in reliability could not be prevented.

Furthermore, as another method, all the image signals for one mark sheet obtained from the reading device are temporarily stored in a storage device, and the scanning line to be referred to is By optimally switching the marks, it will be possible to read marks with extremely high accuracy. However, this method creates new problems in that it requires a large-capacity storage device and the reading device is expensive.

The present invention has been made in order to solve the above-mentioned conventional problems, and it is possible to change the inclination angle of the mark sheet from the start of scanning to the end of scanning without increasing the dimension of the mark entry field in the sub-scanning direction (vertical direction). It is an object of the present invention to provide a mark reading device that can read marks with extremely high accuracy even if the marks change during the period.

A further object of the present invention is to provide a mark reading device that improves the processing speed of mark reading.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a reading means for reading a mark sheet having a plurality of rows of mark entry fields provided at equal intervals between a start reference mark and a stop reference mark. and a storage means that stores information based on the distance between the start reference mark and the stop reference mark in advance, and detects a predetermined number or more of continuous black signals by performing black and white discrimination on all image signals that are sequentially input. Then, after determining whether it is a start reference mark or a stop reference mark based on the entire range search mode for detecting any of the reference marks and the position of the first detected reference mark, based on the information stored in the storage means. a reference mark detection means having a limited section search mode that predicts the position of the reference mark that will appear next and searches for the reference mark only within the predicted range; and control means for correcting the inclination of the reference mark and sequentially determining whether the mark entry field is black or white each time the reference mark detection means changes to a state in which neither of the reference marks is detected.

Effects With the above-described configuration, the present invention can read marks with extremely high accuracy even if the mark sheet is tilted during scanning.

Furthermore, in the limited section search mode, the present invention uses the position of the first detected reference mark and the distance between both reference marks registered in advance.
A limited section on the scanning line where the next reference mark to be detected may appear is predicted, and the search operation for the next reference mark to be detected is performed only in that limited section, so it becomes the target of the search. It is possible to reduce the amount of data and improve processing speed.

Embodiments Hereinafter, the present invention will be described based on embodiments shown in the drawings. In this embodiment, a mark sheet 12 shown in FIG. 4 is used. To explain this mark sheet 12 in more detail, the start reference marks 10 are arranged vertically in the vicinity of the left end of the mark sheet 12. On the other hand,
The stop reference mark 11 is on the mark sheet 1.
They are arranged vertically near the right end of 2. The reference marks 10 and 11 occupy symmetrical positions on the mark sheet 12.

Both the reference marks 10 and 11 are vertically 4
It is a rectangle with a width of 3 mm and a color that can be read by a reading device such as a facsimile machine (for example, black).
The inside of the rectangle is printed solidly.

Further, each row of the mark entry field 8 is provided in an area sandwiched between a pair of start reference marks 10 and stop reference marks 11, respectively. These mark entry fields 8 are 4 mm long and 1 mm wide.
It is printed in white in a color that cannot be read by a reading device (for example, pale green).
And the horizontal interval A of mark entry field 8 is 4mm.
It is said that In addition, each line of mark entry column 8 is as follows.
They are aligned with a pair of start reference marks 10 and stop reference marks 11, respectively.

In addition, when the dimensions and problems of the reference marks 10, 11 and the mark entry field 8 are determined as described above, and the mark sheet 12 is A4 size,
If the article column 9 described next is not provided, approximately 1400 (40 columns x 35 rows) mark entry columns 8 can be set on one mark sheet 12.

The article field 9 is provided together with the mark entry field 8 in an area sandwiched between the row of start reference marks 10 and the row of stop reference marks 11. The shape and size of this article column 9 can be determined appropriately.

FIG. 5 shows a mark detection circuit that detects whether or not a mark is written in each mark entry field 8 based on an image signal obtained from a reading device (not shown) such as a facsimile device in this embodiment. A block diagram is shown. In the figure, 15 is an image signal input terminal for inputting the image signal c obtained by the reading device, and 16 is an image signal clock pulse b (one clock pulse corresponds to one pixel) which is completely synchronized with the image signal c. A clock pulse input terminal is inputted from the reading device, 17 is an image signal section signal input terminal to which the image signal section signal a is inputted from the reading device, and 18 is a scanning start signal input terminal to which the scanning start signal p is inputted from the reading device.

19 is an 8-bit general-purpose microprocessor that controls each part of this circuit, and the main operation of this circuit, which will be described later, is performed by ROM (Read Only Memory) 2.
This is performed by the microprocessor 19 executing a program stored in advance in the microprocessor 19. 21 is a data bus, 22 is an address bus, 2
3 is a control bus.

24 is RAM (Random Access Memory) 3
This image input circuit 24 includes an 8-bit serial/parallel conversion register 25 and a data latch 2.
6, 1/8 frequency divider 27, address counter 28,
DMA control circuit 29 and status register 3
Consists of 0.

Note that the clock pulse b is the serial/
Parallel conversion register 25 and 1/8 frequency divider 27
is input. Further, the 1/8 frequency divider 27 is activated by the image signal interval signal a, and sends a pulse obtained by dividing the clock pulse b by 1/8 to the data latch 26 and the DMA control circuit 29 as the latch pulse signal d.

31 is a black pixel counting circuit that counts the number of black pixels in the section corresponding to each mark entry field 8 of one scanning line, and this black pixel number counting circuit 31 is as follows:
It consists of a 1/8 frequency divider 32, an 8-bit parallel/serial conversion register 33, and an integration counter 34.

An output circuit 36 outputs detected mark data to an external data processing device, and is composed of an output data port 37, a data transfer control circuit 38, and an external interface 39.

6 is a map diagram (area allocation diagram) of the RAM 35, FIG. 7 is an allocation diagram in the work area 40 of FIG. 6, FIG. 8 is an operation timing chart inside the image input circuit 24, and FIG. 9 is a black Pixel counting circuit 3
FIGS. 15 to 17 are flowcharts showing the operation of this mark detection circuit.

Next, the operation of this mark detection circuit will be explained with reference to these figures.

When the reading start position is reached, the scanning start signal p becomes "1", the interval signal a becomes "1", and in synchronization with this, the image signal c is input to the input terminal 15 (the clock pulse b is always Input terminal 17
has been entered. ).

When the interval signal a becomes "1" as described above, the image input circuit 24 becomes operational, and as shown in the timing chart of FIG. The image signal c input serially is
The register 25 converts each 8 bits into parallel signals and transfers them to the data latch 26. The 8-bit image signals transferred to the data latch 26 in this way are then transferred to the RAM 35.
Direct memory access (hereinafter referred to as DMA) is transferred to the RAM 35 and sequentially stored in the first input buffer area 41 or the second input buffer area 42.

The above operation is performed while the interval signal a is “1”.
Continuous. As a result, the image signal c for one scanning line is continuously transferred to the input buffer area 41 or 4.
It will be stored in 2.

Here, the input buffer areas 41 and 42 are
Each has a capacity for one scanning line, and in order to improve processing speed, while various processing described later is being performed on the image signal c of a certain scanning line stored in one input buffer area, the capacity of the other input buffer area is The image signal c of the next scanning line is stored in the input buffer area of .

In this embodiment, since one scanning line is composed of 2048 bits, each of the input buffer areas 41 and 42 has a capacity of 2048/8=256 bytes.

Further, the DMA transfer is performed by the DMA control circuit 29.
DMA request signal f and processor 19
After the DMA response signal g is exchanged,
The address valid signal h is output from the DMA control circuit 29 together with the memory write signal i, and at the same time, the address bus 22 is enabled by this h.
This is realized by setting up the image signal held on the data latch 26 onto the data bus 21.

First, the reference marks 10 and 11 are searched for the image signal stored in the input buffer area 41 or 42 of the RAM 35 as described above. Next, this will be explained.

In this embodiment, the reading device has a resolution of 8 dots/1 mm. As mentioned above, the horizontal axes of the reference marks 10 and 11 are 3 mm, so ideally, on one scanning line, each of the reference marks 10 and 11 is a continuous black signal of 3×8=24 bits. It will appear. Therefore,
In this embodiment, in consideration of the printing accuracy of the mark sheet 12, the inclination of the mark sheet 12 during reading, etc., a permissible range is provided in advance for continuous black signals when determining a reference mark. Specifically, when a black signal of 24±3 bits (i.e., 21 bits (first predetermined value) or more and 27 (second predetermined value) bits or less) is continuous, the reference marks 10 and 11 are detected. shall be.

Note that processing on the image signal stored in the input buffer area 41 or 42 is performed using the working area 40 (see FIGS. 6 and 7) of the RAM 35, but in the initial state, each part of this working area 40 is Everything has been cleared.

Specifically, the search operation for the reference marks 10 and 11 is performed according to the flowchart of FIG. 16. That is, when the black signal is read out after the white image signal, the microprocessor 19 uses the reference mark width counter 48 in the working area 40 of the RAM to count the number n of consecutive black signals, and calculates the number n of consecutive black signals. 28, it is determined that the reference marks 10 and 11 have been detected.

Note that the reference mark detected in the first half of one scanning line is regarded as the start reference mark 10, while the reference mark detected in the second half of one scanning line is regarded as the stop reference mark 11.

In this embodiment, the detected reference mark 1
The trailing edge of 0 and 11 (that is, the last black pixel among n consecutive black pixels) is set as the reference position, and information indicating this reference position is stored in the start reference mark position register 46 and the stop mark position register 46 in the RAM work area 40. The reference mark position register 47 is saved. Note that the contents of the reference mark position registers 46 and 47 are updated each time a new reference mark 10 and 11 is detected, respectively.

When the first reference mark 10 or 11 is detected as described above (if the mark sheet 12 is tilted to the left, the stop reference mark 11 is detected before the start reference mark 10), The search mode register 44 in the working area 40 of the RAM is set, and thereafter the entire section search mode is shifted to the limited section search mode.

Here, in the entire interval search mode, the search operation for the reference marks 10 and 11 is performed in the entire interval of the image signal of each scanning line. However, after the first reference mark 10 or 11 is detected, it becomes possible to predict the section in which the other reference marks 10, 11 will appear. The search operation for the reference marks 10 and 11 is performed only in the section.

That is, in the limited section search mode, the first detected reference mark 10 or 1
1 or the position information of the reference mark 10 or 11 detected thereafter, and the distance between the two reference marks 10 and 11 registered in advance in the ROM 20, a scan in which the reference mark to be detected next may appear. A limited section on the line is determined based on a predetermined criterion, and a search operation for a reference mark to be detected next is performed only in the limited section.

Note that the position of the article column 9 is set so as not to be included in the limited section. FIG. 10 is a timing chart showing the relationship between the image signal and the limited area.

As a result, reference marks 10, 1 are added to article column 9.
Even if a graphic pattern that cannot be distinguished from 1 is written, there is no possibility that the pattern will be erroneously detected as the reference marks 10, 11. Furthermore, since the number of data to be searched is reduced, processing speed is improved.

On the other hand, when the first reference mark 10 or 11 is detected as described above, a detection operation is started to determine whether or not a mark has been written in each mark entry field 8. Next, this will be explained.

The reference mark detection register 45 in the work area 40 of the RAM 35 is set to indicate whether or not the start reference mark 10 and the stop reference mark 11 are detected for each scanning line (if they are detected, "1" is set). ”; if not detected, “0” is set).

Here, when the detection operation of the reference marks 10 and 11 is performed for each scanning line as described above,
For each scan line, four states occur as shown in FIG.

That is, in state 1, the start reference mark 10 and the stop reference mark 11 are detected in one scanning line.
This is a state in which none of the marks have been detected, and is represented by (0, 0) on the reference mark detection register 45.

State 2 is a state in which only either the start reference mark 10 or the stop reference mark 11 is detected in one scanning line, and the register 4
5 is represented by (0, 1) or (1, 0).

State 3 is a state in which both the start reference mark 10 and the stop reference mark 11 are detected in one scanning line, and is represented by (1, 1) on the register 45.

State 4, like state 2, is a state in which only either the start reference mark 10 or the stop reference mark 11 is detected in one scanning line, and also on the register 45 (0,
1) or (1, 0). However, the difference between state 4 and state 2 is that state 2 detects the upper part of reference mark 10 or 11, whereas state 4 detects the lower part of reference mark 10 or 11. be.

Whether or not the document is tilted, and if so, the direction of the tilt, can be determined by looking at the transition process between the four states described above.

That is, if the mark sheet 12 is scanned without being tilted at all, states 2 and 4 will not occur.

Furthermore, when the mark sheet 12 is scanned in a tilted state, state 1 → state 2 → state 3 → state 4
The state changes. In more detail,
When the mark sheet 12 is scanned tilted to the right, (0, 0) → (1, 0) → (1, 1) →
The state transitions from (0, 1) to (0, 0).
Furthermore, when the mark sheet 12 is scanned while tilted to the left, (0, 0) → (0, 1) → (1,
The state transitions from 1) to (1, 0) to (0, 0).

Also, if state 2 is followed by state 4 without passing through state 3, or if state 4 is followed by state 3 without passing through state 1, the mark sheet 12 may be scanned in a very tilted state. It means something. In this embodiment, in such a case, abnormality processing is executed without correcting the inclination of the scanning line, which will be described later. In other words, if the mark sheet 12 is tilted so much that it cannot be corrected, an abnormality process different from the tilt correction process is executed and some kind of countermeasure is taken immediately (for example, the mark sheet 12 is read again, etc.). ).

Further, unless the mark sheet 12 is abnormally tilted, the state changes from state 3 or state 4 to state 1 at the end of each line in the mark entry field 8. Therefore, in this embodiment, when such a transition occurs, it is assumed that one line in the mark entry field 8 has been completed, and line data processing, which will be explained in detail later, is executed.

A state transition diagram and a state transition table between the above-mentioned states are shown in FIGS. 12 and 13. Note that in FIG. 13, the "Status" column indicates the state of the previous scanning line;
The "input" column indicates the status of the next scanning line.

Based on the above, in this embodiment, while referring to which of the four states each scanning line corresponds to, through the reference mark detection register 45,
Mark detection processing on the mark entry field 8 is performed. Next, this will be explained using FIGS. 7 and 14.

First, in the scanning line in state 1, since no image signal corresponding to the mark entry field 8 is included, mark detection processing is not performed.

For the scanning line in state 2, the reference position is known from one of the detected reference marks, and the scanning line is moved from that reference position at every horizontal interval A of the mark entry field 8 registered in the ROM 20 in advance. Then, the black pixel counting circuit 31 counts the number of black pixels included in the portion corresponding to the mark entry field 8 within the divided section. That is, in this embodiment, black and white discrimination of the image signal is performed only within the interval based on the horizontal direction of the mark entry field 8 registered in advance in the ROM 20.

For example, if the start reference mark 10 is detected, that is, in the case of (1, 0), four scanning lines are scanned from that position based on the reference position information saved in the start reference mark position register 46.
The black pixel count circuit 31 counts the number of black pixels included in each portion corresponding to the mark entry field 8 within the divided 4 mm section. In this way, since the number of black pixels is counted only in the portion corresponding to the mark entry field 8, the processing speed is significantly improved.

Here, the black pixel counting 31 specifically counts the previous black pixels as follows (a timing chart thereof is shown in FIG. 9).

That is, the microprocessor 19 sends the activation pulse r to the parallel/serial conversion register 33 and the 1/8 minute period 32, and at the same time sends the image signal in the section corresponding to the mark entry field 8 from the RAM 35 to the register 33 in parallel via the data bus. Output. When the activation signal r is input, the 1/8 minute period 32 supplies a data shift pulse u to the register 33, causes the register 33 to serially output the image signal to the integration counter 34, and at the same time, the image signal is While being input to the pixel integration counter 34,
The integration interval signal s is output, and the integration counter 34 is kept in an operating state during that period. Thereby, the integration counter 34 counts the number of black pixels in the section corresponding to each mark entry field 8.

On the other hand, the eight line registers 52(1) to (8) on the working area 40 of the RAM each have a capacity of 40 bits, corresponding to the number of mark entry fields 8 in one line, which is 40.

Now, assuming that processing is being performed on the scanning line that has entered the second state for the first time, the microprocessor 19 inputs the counting results of the integration counter 34 corresponding to each mark entry field 8 through the data bus 21. , and a predetermined threshold value S1, and if the counting result is equal to or greater than the threshold value S1, the corresponding bit of the first line register 52(1) is set to "1", while the counting result is equal to or greater than the threshold value. S1 is set to 2.

Next, in the same way, the microprocessor 19
also compares the counting result of the number of black pixels in the section corresponding to each mark entry field 8 with the threshold value S1 for the second scanning line that has reached the second state, and according to the comparison result, The corresponding bit of the line register 52(2) is set to "1" or "0", and the corresponding line register 52(2) is set to "1" or "0" in the same way for the third and subsequent scanning lines that are in the second state. 3) Set the corresponding bits of 52(8) to "1" or "0".

Here, in this embodiment, the line register 5
The reason why the number of 2's is set to 8 is as follows.

The number of scanning lines that continuously enter state 2 depends on the inclination angle of the mark sheet 12, and the maximum number of scanning lines K
is determined by the maximum allowable tilt angle θ of the mark sheet 12. In this embodiment, it is assumed that state 2 always passes through state 3 to state 4, so the distance L1 between the reference marks 10 and 11 located on both sides of the mark entry field 8 of one line, the reference mark 10,
If the vertical length of No. 11 is L2, the maximum allowable tilt angle θ is as follows: θ=arctan(L2/L1).

If L1=160mm and L2=4mm, θ≒1.4°.

The maximum number of scanning lines K at this time is K=L2/D, where D is the pixel density.

Therefore, if D=0.5 (2 pieces/mm), then K
=8. Therefore, in this embodiment, the number of line registers 52 is eight.

Note that in this embodiment, the number of scanning lines that are continuously in state 2 is sequentially counted by the slope counter 51. The total number indicates the inclination angle of the mark sheet 12, as described above.

Also, as described above, the line register 52
The data regarding the one-line mark entry column 8 for state 2 stored in (1) to 52 (8) is state 2.
When transitioning from state 3 to state 3, the following processing is performed.

First, line registers 52(1) to 52(8)
All data stored in the slope counter 51
The data is separated into valid data and invalid data according to the content of the data. That is, based on the contents of the slope counter 51, the valid slope (shaded area) in FIG. 14 is separated from the other invalid areas, and the data within the valid area is set as valid data.

On the other hand, the bit counters 53 are prepared in the same manner as the mark entry fields 8 for one line (40 pieces), and each bit counter 53 corresponds to one of the mark entry fields 8 for one line. And these bit counters 53(1)
~53 (40), the line register 5 is entered as valid data for each mark entry field 8 in one line.
The number in which "1" is set in 2(1) to 52(8) is counted.

Next, regarding the scanning line in state 3, the following processing is performed.

First, in the same way as for the scanning line in state 2, the black pixel counting circuit 31 is caused to count the number of black pixels in the section corresponding to each mark entry field 8 in one row. The section corresponding to each mark entry field 8 is determined based on the reference position information of both the references 10 and 11 saved in the reference mark position registers 46 and 47.

However, in state 3, all the image signals are included in the effective area as shown in FIG. 1) to 52(8) are not operated. Then, the counting result of the black pixel counting circuit 31 for the section corresponding to each mark entry field 8 is compared with the threshold value S1, and if it is equal to or greater than S1,
Immediately, the corresponding bit counter 53 is incremented by 1, while if it is smaller than S1, the corresponding bit counter 53 is kept unchanged.

Next, regarding the scanning line in state 4,
The same processing as that for the scanning line is performed.

On the other hand, the start reference mark vertically long counter 49
is "state 3 → state 1" or "state 4 → state 1"
start reference mark 10 until there is a transition (that is, until one line of mark entry field 8 ends).
Count the number of scan lines detected. Similarly,
The stop reference mark vertically elongated counter 50 counts the number of scanning lines in which the stop reference mark 11 is detected until there is a transition from "state 3 to state 1" or "state 4 to state 1".

If the counting results of both vertical counters 49 and 50 are not within the predetermined range determined based on the vertical length of the reference marks 10 and 11, the row data of the corresponding mark entry field 8 will be explained below. No processing is performed. As a result, mark sheet 12
Furthermore, even if there is a mark or stain that has the same or similar width as the fiducial marks 10, 11 but is different in length, there is no possibility that the fiducial marks 10, 11 will be mistaken for the fiducial marks 10, 11.

The row data processing includes the "state 3 → state 1"
Alternatively, it is executed after the transition from "state 4 to state 1" occurs and after the counting results of the vertical counters 49 and 50 are confirmed. This row data processing is
The bit counters 53(1) to 53(4), which have performed the counting through states 2, 3, and 4,
Compare the final value of 0) with the threshold S2, and if it is greater than or equal to S2, set it to "1", and if it is smaller than S2, set it to "0".
The content is to set the corresponding bit in the output buffer area 39 of the RAM 35.
Here, the "1" means that it has been determined that a mark has been entered in the mark entry field 8, and "0"
means that it has been determined that no mark has been entered. In addition, in this embodiment, the threshold value S2 is
It is set to 4.

The above operation is repeated for each row of the mark entry field 8, and the mark detection results for each row are sequentially stored in the output buffer area 39.

Then, when the scanning start signal p becomes "0", the above operation is completed, and the mark detection results for each mark entry field 8 stored in the output buffer area 39 are sent to an external data processing device (not shown) through the output circuit 36. will be forwarded to ). Note that the output circuit 36
In addition to the mark detection result, the output circuit 36 outputs a control signal for interfacing with the data processing device, but since this output circuit 36 is a part that is designed depending on the type of data processing device, details will be explained. Further explanation will be omitted.

As described above, in this embodiment, marks are placed in the mark entry field 8 while monitoring the inclination angle and direction of the mark sheet 12 based on the four states expressed by the presence or absence of detection of the left and right pair of reference marks 10 and 11. Since it detects whether or not the mark sheet 12 is written, even if the inclination angle of the mark sheet 12 changes from the start of scanning to the end of scanning, the inclination angle can be appropriately compensated and marks can be read with extremely high precision. Can be done.

Note that the mark detection circuit shown in FIG.
It may be connected to a facsimile transmitter or a facsimile receiver.

Further, it goes without saying that the optical reading device according to the present invention is not limited to a facsimile device.

Further, in the embodiment described above, processing is performed on the assumption that only four states can occur as the detection states of the start reference mark and the stop reference mark in each scanning line, but there are many more states, for example, in one scanning line. If processing is carried out assuming that a state in which a start reference mark in one row and a stop reference mark 10 in the next row are detected may occur, marks can be detected with high precision even if the mark sheet is tilted even more.

Effects of the Invention As described above, the present invention provides a reading means for reading a mark sheet having a plurality of rows of mark entry fields provided at equal intervals between a start reference mark and a stop reference mark, and a storage means for storing information based on the distance between the stop reference mark and the stop reference mark; and a storage means for storing information based on the distance between the stop reference mark and the stop reference mark; After determining whether it is a start reference mark or a stop reference mark based on the position of the first detected reference mark, the reference mark that appears next based on the information stored in the storage means is determined. a reference mark detection means having a limited interval search mode for predicting the position of the reference mark and searching for the reference mark only within the predicted range; The control means sequentially performs black and white discrimination of the mark entry field each time the reference mark detection means transitions to a state in which neither of the reference marks is detected. To perform highly accurate mark reading without increasing the dimensions, even if the mark sheet is tilted during scanning, or even if the inclination angle of the mark sheet changes from the start of scanning to the end of scanning. The excellent effect of being able to do this can be obtained.

Furthermore, according to the present invention, information based on the position of the fiducial mark detected first and the distance between the two fiducial marks registered in advance is used to determine the limit on the scanning line where the fiducial mark to be detected next may appear. The search operation for the next reference mark to be detected is performed only in that limited section, reducing the amount of data to be searched.
The effect of improving processing speed can also be obtained.

[Brief explanation of the drawing]

Figure 1 is a front view of an example of a conventional mark sheet.
Figure 2 is a front view of another example of a conventional mark sheet.
3 is a front view of still another example of a conventional mark sheet, FIG. 4 is a front view of a mark sheet used in a mark reading device according to the present invention, FIG. 5 is a block diagram of a mark detection circuit in the above embodiment, and FIG. 7 is a map diagram of the RAM 35 in the mark detection circuit, FIG. 7 is an allocation diagram in the work area 40 of FIG. 6, FIG. 8 is a timing chart of the image input circuit 24 in the mark detection circuit, and FIG. A timing chart of the black pixel counting circuit 31 in the mark detection circuit, FIG. 10 is a timing chart showing the reference mark detection operation in the limited section search mode in the mark detection circuit, and FIG. 11 is a timing chart of the start reference mark and An explanatory diagram showing the four states depending on whether or not a stop reference mark is detected, FIG. 12 is a state transition diagram between the four states, FIG. 13 is a state transition table between the four states, and FIG. 14 is the state 15 to 17 are flowcharts of the embodiment described above. 8...Mark entry field, 9...Article field, 10...
Start reference mark, 11...Stop reference mark, 12...Mark sheet, 19...Microprocessor, 24...Picture signal input circuit, 31...Black pixel counting circuit, 36...Output circuit.

Claims (1)

[Claims] 1. A reading means for reading a mark sheet having a plurality of rows of mark entry fields provided at equal intervals between a start reference mark and a stop reference mark;
A storage means for storing information based on the distance between the start reference mark and the stop reference mark in advance, and a black and white discrimination of all the sequentially inputted image signals, detect a predetermined number or more of continuous black signals, and After determining whether it is a start reference mark or a stop reference mark based on the entire range search mode in which any one of the reference marks is detected and the position of the first detected reference mark, the next one is determined based on the information stored in the storage means. a reference mark detection means having a limited section search mode for predicting the position of the reference mark that will appear and searching for the reference mark only within the predicted range; and determining the inclination of the scanning line based on the detection result of the reference mark detection means. and control means for sequentially performing black and white discrimination of a mark entry field each time the reference mark detection means changes to a state in which neither of the reference marks is detected.