JPH0413637Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a print management data detection device for a flatbed proofing printing press that measures a printed print management scale.

[Technical background of the invention and its problems] In general, a pattern part and various management scales are printed on a printed matter printed by a proof printing machine. Printed matter is managed by proofreading and printing operators measuring the density using this management scale, but with this management method, density measurement is troublesome and the work time required to collect print management data is long. Therefore, the measurement frequency becomes low, and there are problems such as printing conditions changing if the ink or blanket roll is left for a long time.

In order to solve these problems, a special application was filed in 1983.
006752 (Japanese Unexamined Patent Publication No. 60-151051) discloses that a printed print management scale is irradiated with light, the reflected light from the print management scale is detected, and this is processed to create print management data that indicates the printing status. A flatbed proofing press has been proposed that obtains the

The print management data detection device of this flatbed proofing printing machine has a function as a so-called reflection densitometer, and as shown in FIGS. The light source 4 is arranged so that a beam spot with a diameter of ~5 mm is formed.
The irradiated light is focused on the printing management scale through the pinhole 6 and the condensing lens 8, and the reflected light from the area where the irradiated light is focused is transmitted through the condensing lens 10 and the pinhole 12. It is introduced into the photodetector 14. In such a detection device for print management data, it is required that the optical arrangement of the light source, sample surface, and photodetector be constant, as shown in FIG. 2a.
Under such conditions, the density of the printing control scale can be accurately measured. If for some reason, for example, the printing paper floats on the surface plate due to the tack of ink immediately after printing, the light source 4, the sample surface 2, the photodetector 14 and the sample surface 2, as shown in FIG. If the distance d is smaller than the predetermined distance, there is a problem that the density of the print management scale cannot be accurately measured. That is,
When the distances between the light source 4 and the sample surface 2 and between the photodetector 14 and the sample surface 2 are set to predetermined distances as shown in FIG. 2b, the beam spot as shown in FIG. is formed on the sample surface 2. This beam spot is irradiated with focused light from an oblique direction to the sample surface, and since the light spot is a filament with a certain size, it is formed into an elliptical shape with a certain size even in the focused state. be done. Therefore, it has a light intensity line distribution as shown in FIG. 4a, and the light intensity contour lines in the beam spot have an elliptical distribution as shown in FIG. 3a. Here, the reflected light reflected from the photometric point within the elliptical beam spot is introduced into the photodetector 14. As shown in FIG. 2b, the light source 4, the sample surface 2 and the photodetector 14
When the distance between the sample surface 2 and the sample surface 2 becomes smaller than the predetermined distance by the distance d, the elliptical beam spot on the sample surface 2 becomes larger and its light intensity distribution also decreases as shown in FIG. 4b. . Moreover, as shown in FIG. 3b, the photometric point is formed in a region having low light intensity. As a result, even when measuring the same concentration scale, the light source as shown in Fig. 2b is smaller than that in the case where the optical arrangement of the light source, sample surface, and photodetector is constant as shown in Fig. 2a. 4 and the sample surface 2, and when the distance d between the photodetector 14 and the sample surface 2 becomes smaller than the predetermined distance, the photodetector 14
In this case, a low level signal is generated, and the density of the printing control scale cannot be accurately measured.

[Purpose of the invention] The object of the invention is to print even if the optical arrangement of the light source, sample surface, and photodetector changes slightly, in the same manner as when the optical arrangement of the light source, sample surface, and photodetector is constant. An object of the present invention is to provide a data detection device for printing management of a flatbed proofing printing press that can accurately measure the density of a management scale.

[Summary of the invention] According to this invention, there is a mounting table on which a printed matter with a print management scale is placed, a light source optical system that emits light toward the print management scale, and a light source that emits light toward the print management scale, and a light source that emits light toward the print management scale. and a filter that transmits the light emitted from the light source optical system and converts it into transmitted light having a light intensity distribution that increases from the center to the periphery. A data detection device for print management of a flatbed proofing press is provided.

[Sample surface of the invention] Fig. 1a shows a data detection device for print management of a flatbed proofing printing press according to an embodiment of the invention, and a case 22 includes a light source device 2 incorporating a lens.
4 and a photodetector 26 are fixed to the frame. A color separation filter 28 is arranged in front of the photodetector 26, and the color separation filter 28 and the printed matter 30, which is the sample surface placed on the mounting table 20,
A condensing lens 32 is arranged between the two and the condensing lens 32 to condense the reflected light from the print management scale of the printed matter 30. Between the sample surface 30 and the light source device 24,
Light transmittance increases from the center to the periphery.
An ND filter 34 is provided. Note that the reference numeral 36 indicates a circuit board of the device.

In such a print management data detection device for a flatbed proof printing press, a convergent light beam emitted from the light source device 24 is irradiated onto the print management scale of the printed material 30 via the ND filter 34,
The light is reflected by this scale and directed toward the condenser lens 32. The reflected light focused by the condenser lens 32 is
The light enters the light detection device 26 via the color separation filter 28. The signal generated from the photodetector 26 is supplied to an arithmetic processing circuit (not shown), where it is arithmetic-processed and converted into print management data indicating the printing status.

In the data detection device for print management of the flatbed proofing printer described above, the sample surface 30 and the light source device 24
Since an ND filter 34 whose light transmittance increases from the center to the periphery is inserted between the sample surface 30 and the ND filter 34, the sample surface 30 has a light intensity distribution as shown in FIG. The beam spot is shown in Figure 5a.
It is formed as shown in . As is clear from the light intensity distribution and light intensity contour distribution shown in FIG. 5, this beam spot is dark at the center and bright at the periphery. Therefore, if the distance between the photodetector 26 and the sample surface 30 becomes smaller than the predetermined distance by the distance d as shown in FIG.
The upper elliptical beam spot becomes larger and its light intensity distribution is reduced, but the photometric point is formed in a peripheral region where the light intensity is greater than that at the center.
As a result, even when the optical arrangement of the light source, the sample surface, and the photodetector is constant, the distance between the photodetector 26 and the sample surface 30 is slightly smaller than the predetermined distance d. Even in such a case, the photodetector 26 generates signals of the same level for the same density scale, so that density data of the print management scale can be accurately obtained.

[Effect of the invention] According to the present invention, even if the optical arrangement of the light source, sample surface, and photodetector changes slightly, printing can be performed in the same way as when the optical arrangement of the light source, sample surface, and photodetector is constant. A print management data detection device for a flatbed proofing printing press is provided that can accurately measure the density of a management scale.

[Brief explanation of the drawing]

1A and 1B are schematic cross-sectional views showing a data detection device for print management of a flatbed proofing printing press according to an embodiment of the present invention, and FIGS. Schematic diagram showing the optical system of the data detection device, Fig. 3 a and b and Fig. 4 a and b
5A and 5B show the light intensity contour distribution and light intensity distribution of the beam spot formed on the sample surface in the optical system of the print management data detection device of the conventional flatbed proofing printer, and the flatbed proofreading of this invention. Light intensity contour distribution and light intensity distribution of a beam spot formed on a sample surface in the optical system of a data detection device for print management of a printing press.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A mounting table on which a printed matter on which a print management scale is printed, a light source optical system that emits light toward the print management scale, and a light source that emits light toward the print management scale, and and a filter that transmits the light emitted from the light source optical system and converts it into transmitted light having a light intensity distribution that increases from the center to the periphery. Features: Data detection device for print management of flatbed proofing presses. (2) The data detection device for print management of a flatbed proofing printing press according to claim 1, wherein the filter is an ND filter.