JPH0288907A - Printer printing accuracy measurement method and device - Google Patents

Abstract

PURPOSE:To reduce the labor for measurement, to improve reliability, to accomplish high speed operation and to facilitate the statistical grasp of data by detecting both corners of the edges of paper with a camera eye, measuring the tilt angle of the front edge of the paper and then measuring the positions of test marks on a start point and an end point. CONSTITUTION:The paper where the test mark is printed by a printer is held on a table 6 and both corners of the front edges of the paper are detected with the camera eye 8 so as to measure the tilt angle. Then, the test mark which becomes the measurement start point and the test mark which becomes the measurement end part are detected with the camera eye 8 to measure the positions of the test marks on the start point and the end point. Thus, the position of the corner and the tilt angle of the paper on the table 6 are detected first. Then, the approximate position of the test mark which is going to be detected next can be calculated. By moving the camera eye 8 quickly, the mark is rapidly detected and a position measuring action can be quickly performed. Since measuring accuracy does not depend on positioning accuracy of the paper, the measurement with high accuracy can be accomplished by using position measuring scales 23 and 24.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a method and device for measuring the printing accuracy of a computer printer, which automatically feeds paper with test marks printed at predetermined positions. The present invention relates to a device capable of automatically measuring the mutual positional accuracy of test marks and automatically processing the measurement data.

(Prior Art) When a printer manufacturer performs a test run of a product or a user maintains and manages a printer, a printer prints a predetermined test mark on paper and inspects the printing accuracy. Conventionally, this inspection has been carried out by simple visual inspection, but when high precision is required, various scales and optical instruments are used to carry out this inspection.

(Problems to be Solved by the Invention) However, in the conventional method described above, the reliability is poor because the measurement is done visually, and when trying to make high-precision measurements, it takes time and effort for work and setup, and inspection There is a lack of clarity in determining the quality of results, cumbersome administrative work is required to accumulate and manage measurement data, and it is troublesome to create materials such as tables, graphs, and statistical values for statistical quality control. However, there were several problems, such as the fact that it required a huge amount of effort to perform sufficient quality control and maintenance management.

Therefore, an object of the present invention is to automatically measure the printing accuracy of test marks on paper printed by a printer using a camera, thereby facilitating quality control and maintenance management of the printer.

(Means for Solving the Problems) The method of the present invention is to hold a sheet of paper on which a test mark has been printed with a printer on a table, detect both front corners of the sheet with a camera eye, and determine the inclination angle of the leading edge of the sheet. Then, the camera eye detects the test mark that is the measurement start point and the test mark that is the measurement end point, and the positions of the test marks at the start and end points are measured.These measured values are recorded and calculated to determine the printing accuracy. The device of the present invention is characterized by measuring the number of sheets, and the apparatus of the present invention includes an automatic paper feeder 5 that separates stacked sheets into individual sheets and feeds them onto a measuring table 6; 32 on the measurement table, a camera eye 8 disposed above the measurement table, a traveling device 19, 20 that moves the camera eye two-dimensionally with respect to the measurement table, and scales 23 and 24 for detecting the moving position; means E for detecting and setting the inclination angle of the leading edge of the paper on the measurement table using the camera eye and the scale; means F for calculating and measuring the mutual positional relationship between the plurality of test marks by reading the center of gravity of the test marks at the positions and referring to the inclination angle of the paper measured by the means E; It is characterized in that it is equipped with an automatic paper ejecting device 17. The paper inclination angle detection/setting means E and the test mark reading calculation/measuring means F in the above-mentioned apparatus are constituted by software of the computer 1.

(Function) According to the above method and the above device implementing the method, the corner position and inclination angle of the paper on the table are first detected, and the approximate position of the next test mark to be detected is based on the detected values. can be calculated, the camera eye can be quickly moved to the position of the test mark to be measured, and mark detection and position measurement operations can be performed quickly. Furthermore, since the measurement accuracy does not depend on the positioning accuracy of the paper on the table, automatic paper feeding can be easily performed and measurement errors can be reduced. Furthermore, by using the camera eye 8 that moves on the paper and its position measurement scales 23 and 24, it is possible to measure high brightness, and the measurement data is measured and recorded as a digital electrical signal, so the data is Processing such as aggregation and calculation becomes easier.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.゛Figure 2 is a hardware configuration diagram of the device of this invention, and Figure 3 is an overall perspective view, in which 1 is a personal computer that controls the device and performs arithmetic processing of measurement data, 2 is its display, and 3 is a keyboard for operation commands. , 4 is a printer for outputting measurement data, 5 is its automatic paper feeding device, 6 is a measurement table arranged in connection with the paper ejection path of the printer 4, and 7 is a measurement table 6 that is movable in the Y direction in the figure. 8 is a CCD camera arranged above the measurement table; 9 is a camera carrier that holds the CCD camera 8; 10 is a travel guide that supports the camera carrier 9 so as to be movable in the X direction in the figure; A corner detection sensor is provided so as to surround the CCD camera 8 in an L shape, and a partial plan view thereof is shown in FIG. 12 is CCD camera 8
13 is a video monitor of the COD camera 8; 14 is a visual device controller that controls the CCD camera 8 and the video monitor 13; 15 is a device for stamping inspection results on paper; 16 is a paper discharge arm , 17 is a paper discharge pad provided at the tip of the paper discharge arm 16, 18 is a paper discharge stacker, 19 is a pulse motor that moves the measurement table 6 in the Y direction in the figure, and 20 is a camera carrier 9 that is perpendicular to the table 6. Pulse motor for running in the X direction, 21
and 22 is a pulse generator, 23 is a measurement table 6
24 is a Magnescale for detecting the position of the camera carrier 9, and 25 is a display unit for the measured values of the Magnescales 23 and 24.

As shown in FIG. 5, the measurement table 6 is provided with a slit 27 in its running direction, and a lower end protrusion sensor 28 and an upper end protrusion sensor 29 are provided near the paper feed side (printer side) edge and the paper discharge side edge. It is provided. Further, as shown in FIG. 6, two air vents 30a and 30b are provided at the edge of the paper feed side of the table 6 on the top surface of the table and at a slightly higher position facing the paper ejection direction at equal intervals. pipe 3
1a and 31b are stacked horizontally, and the paper 32 is placed on an air vibrator 31a.
, 31b onto the table 6. When paper is fed as shown in FIG. 7, the air vibrators 31a and 31b are located close to the paper ejection roller 33 of the printer 4, air is blown out from the air blow holes 30a and 30b, and the airflow causes the paper 32 to touch the table 6. The sheet is smoothly fed in an expanded state between the sheet holding plate 34 described later. This air flow is particularly effective in preventing paper jams when using thin paper. The table 6 is provided with a paper press plate 34 made of a transparent plate on the upper side.
descends and clamps and fixes the paper on the table 6.

Below the slit 27 provided in the table, as shown in FIG. 8, a suction pad 35 that adsorbs the lower surface of the paper 32 with negative pressure air is provided so as to be movable up and down and to be movable in the same direction as the running direction of the table 6. A paper detection sensor 36 is mounted adjacent to the suction pad 35 so as to be able to detect the paper 32 through the slit 27.

As shown in FIGS. 9(a) and 9(b), the paper ejection side edge of the table 6 protrudes from the paper pressing plate 34, and the stamping device 15 and the paper ejection pad 1 are arranged opposite to the protrusion 6a.
7 are arranged side by side in the direction perpendicular to the plane of the drawing. The stamping device 15 moves up and down toward the paper 32 that is being ejected and stamps a pass/fail mark on the inspected paper 32, and the paper discharge pad 17 attracts the paper 32 and moves it.
2 from the table 6 to the paper discharge stacker 8. An air pipe 37 is arranged at the end of the main body frame on the paper ejection side, and when paper is ejected, this pipe 37
Air is blown out to lift the paper 32 and ensure smooth ejection of the paper 32.

An outline of the operation of this inventive device is shown in the flowchart of FIG.
This is shown in the flowcharts of FIGS.

The table initial setting operation A shown in detail in FIG. 10 is an operation in which the measurement table 6 is moved to the paper feeding side moving end. The origin position of the measurement table 6 is set at the discharge side moving end, and if the table 6 is not at the origin position at the start of measurement, it moves once to the origin position and then moves to the sheet feeding side moving end. Further, if the CCD camera 8 is not at the origin position (the moving end on the reference side side of the paper) at the start of measurement, it is moved to the origin position. The illustrated device is configured so that it can be switched between an automatic mode in which continuous measurement is performed using automatic paper feeding, and a manual mode in which the operator measures the paper loaded on the table. An emergency stop occurs when there is paper on the machine, and if it is in manual mode,
If no paper is loaded, an emergency stop will occur. table 6
After setting the CCD camera 8 to the measurement start position, the counters of the Magnescale are cleared in both the X and Y directions.

Paper feeding operation B and paper positioning operation C, details of which are shown in FIGS. 11 and 12, are executed in the automatic mode. In the illustrated embodiment, the measuring paper 32 is fed onto the table 6 using the automatic paper feeding device 5 of the printer. The paper 32 is fed from the automatic paper feeder to the printer 4, and the sample number attached to the measurement data of the paper is printed on the paper by the printer 4. The paper after the sample number has been printed is discharged from the printer 4 with conveying air blown out from the air vibrator 31, and guided between the table 6 and the paper press plate 34 (see FIG. 6.7). Once the paper is properly fed, the paper 32 is temporarily held by the paper pressing plate 34.

The paper 32 automatically fed by the above operation is placed on the measurement table 6.
Since the lower end of the sheet is protruding from the sheet, the sheet is moved to the center of the measuring table 6 by sheet positioning operation C shown in FIG. The table 6 holding the paper 32 is moved toward the paper discharge side, and when the paper detection sensor 36 (see FIG. 8) detects the leading edge of the paper, the table 6 is moved a little further and then stopped. Then, the suction pad 35 is raised to suction the paper 32, the paper pressing plate 34 is released, and the table 6 is moved to the paper feeding side until the lower end protrusion sensor 28 is turned off. With this operation, the paper is relatively transferred to the center of the table, where the paper is again clamped, and the holding of the paper by the suction pads 35 is released.

In the paper corner detection operation shown in detail in Fig. 13, CO
2 installed in an L shape near D camera 8
The camera is positioned at the reference corner of the measurement paper using two corner detection sensors lla and 11b (see FIG. 4). In this operation, first move the table 6 to the paper feed side moving end,
The table 6 is moved toward the paper discharge side while the camera 8 is moved to a position where it touches the front edge of the paper 32 near the reference corner. Then, the table 6 is moved a predetermined distance from the position where the first corner detection sensor lla detects the leading edge of the sheet and then stopped. Next, set camera 8 to the origin (the moving end of the paper reference side example)
After returning the paper, run it toward the paper. and the second
The camera 8 is moved a predetermined distance from the position where the corner detection sensor 11b detects the paper reference side and then stopped. At this position, the reference corner of the paper is located approximately at the center p of the camera. The predetermined amount is the offset amount (lt, ig in FIG. 4) between the camera center p and the detection position of the corner detection sensor, and by providing this, it is possible to perform corner detection at high speed.

Details of the next sheet inclination angle measurement operation E are shown in FIG. First, the shadow area of the camera 8 is illuminated with an illumination lamp, the corner position is read with the two-dimensional CCD of the camera 8, the center p of the camera is aligned with the corner, and the position of the table 6 and camera carrier 9 at this time is determined using the Magnescale. 23.
Read at 24. Next, the inclination angle of the leading edge of the paper is read using the two-dimensional CCD of the camera 8, and the position of the opposite corner is calculated from the given paper width and inclination angle, and the camera and table are moved. Then, in a similar manner, the position of the opposite corner is read by the Magnescale 23, 24, and the accurate inclination angle of the leading edge of the sheet is calculated from the coordinates of both corners and stored.

If the corner cannot be found immediately due to folded paper, etc., a search operation is performed to search for the corner without moving the camera 8 slightly.

FIG. 15 shows the details of the operation F for measuring the position of the test mark on the paper. Test marks consist of + marks placed horizontally on the paper, and printing accuracy is determined by multiple + marks (one or more pairs of start point mark and end point mark. Measurement items such as line spacing, skew, column spacing, etc.) , a start point mark and an end point mark are specified, but the start point mark may normally be the first printing position.

) and calculate the mutual positional relationship. Therefore, the operation of the apparatus is repeated by aligning the camera with a desired test mark and reading the position of the camera and table with the Magnescale 23, 24. In the illustrated example, preliminary positioning of the camera is first performed with the camera field of view set to the normal field of view, and then main positioning is performed with the camera field of view narrowed (up) to read the coordinates. Each positioning operation is performed using the camera's two-dimensional CCD.
This is done by measuring the center of gravity of the mark within the field of view, and aligning the center of the camera with that center of gravity. After reading the coordinates of a pair of start point mark and end point mark, calculate their positional relationship, correct the calculated value using the previously measured inclination angle of the leading edge of the paper, and store it. , the illumination lamp 12 is extinguished and the camera 8 and table 6 are returned to their original positions.

The paper on which the measurement has been completed is transferred according to the procedure shown in FIG.
6, and after adsorbing the paper with the suction pad 35 at the position, the paper pressing plate 34 is raised to move the table 6 and the suction pad 35 to the paper discharge side moving end. In this state, the trailing edge of the paper is transferred to near the protruding area 6a on the paper discharge side of the table, so a pass/fail mark based on the printing accuracy measured in this state is stamped on the paper by the stamping device 15, and then the paper is placed on the paper discharge side. At step 17, the paper is sucked and moved onto the stacker, and the paper is ejected and dropped. When the paper is transferred and discharged, paper discharge air is blown out from the air vibrator 37 to ensure smooth transfer and discharge of the paper.

In the automatic mode, after the paper 32 is ejected, the measurement operation for the next paper is performed, and when the measurement for all the paper is completed, the measurement operation is ended. In the manual mode, the measurement operation ends when the measurement for one sheet of paper is completed.

(Effects of the Invention) By using the device of this invention, the process from automatic paper feeding to measurement and stamping and ejection can be repeated and repeated automatically, eliminating the need for visual measurement of the paper name and improving the reliability of the measurement data. This makes it easier to improve data processing speed, speed up data processing, and statistically understand data.

For example, the device of the present invention can be used to evaluate the performance of prototype printers, to perform sampling inspections of printing accuracy at printer manufacturing factories, and to manage the printing accuracy of printers by users. This makes it easier to discover defects and abnormalities, which can be useful for total quality assurance.

In addition, in the device of the present invention, the inclination of the paper on the table is measured in advance and then the test mark is detected.
The measurement accuracy is not affected by the positioning accuracy of the paper, making it easier to set the paper, and the camera can be moved and positioned to a predetermined test mark position more quickly and accurately.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, in which Fig. 1 is a flowchart showing the overall operating procedure, Fig. 2 is a block diagram showing the hardware configuration, Fig. 3 is a perspective view of the entire device, and Fig. 4 is a flowchart showing the overall operating procedure. C
Fig. 5 is a plan view of the measurement table; Fig. 6 is an enlarged sectional view of the edge of the measurement table on the paper feeding side; Fig. 7 shows the relationship between the printer and the measurement table during paper feeding. 8 is a sectional view schematically showing the suction pad below the measurement table and the paper detection sensor, and FIGS. 9(a) and 9(b) are side views schematically showing the positional relationship between the The sectional views schematically showing the structure and FIGS. 1O to 16 are flowcharts showing details of the operating procedure. In the figure, ■ = personal computer 5: automatic paper feeder 6: measurement table F3: CC
D camera 17: Paper ejection pad 19.207 pulse motor 23.24: Magnescale 32: Paper E: Paper inclination angle measurement operation F: Test mark position measurement operation

Claims (2)

[Claims] (1) Hold a sheet of paper with a test mark printed on it on a table, detect both edges of the sheet with a camera eye, and measure the inclination angle of the leading edge of the sheet from the position of the camera eye at the time of detection. Then, the camera eye detects the test mark that is the starting point of measurement and the test mark that is the ending point of measurement, and the positions of the starting and ending test marks are measured from the position of the camera eye at the time of detection, and these measured values are recorded. A method for measuring the printing accuracy of a printer, which is characterized by calculating. (2) Separate the stacked papers one by one and use the measurement table (
6) An automatic paper feeder (5) that feeds the paper onto the measuring table, a paper holding device (34) that fixes and holds the fed paper (32) on the measuring table, and a camera eye ( 8) and the camera eye against the measurement table.
Traveling devices (19), (20) for dimensionally moving and scales (23), (24) for detecting the moving position thereof;
means (E) for detecting and setting the inclination angle of the leading edge of the paper on the measurement table using the camera eye and the scale; and a test mark at a predetermined position on the paper by moving the camera eye to a predetermined position on the paper. Means (F) for reading the position of the center of gravity of the paper and calculating and measuring their relative positions with reference to the inclination angle of the paper.
and an automatic sheet ejection device (17) on a table.