JPS6179141A - Measuring device for optical characteristic of paper - Google Patents

Abstract

PURPOSE:To improve measurement precision by forming a spectrum which is predetermined on the basis of a wavelength calibration command on a linear array sensor, and calibrating the correspondence relation between wavelength and respective elements of the linear array sensor. CONSTITUTION:The optical characteristic measuring device for paper consists of a detection part 3 composed of a housing for storing an optical system, etc., an O-shaped frame which allows two housing to face each other across a running sheet of paper 4 and constitutes a base for running forth and back in a fixed section in the width direction of the paper 4, and an arithmetic control part which runs the detection part 3, switches measurement and calibration, and processes signals from the detection part 3. Then when a wavelength calibration command is sent, a mercury vapor lamp 13 is turned on instead of a halogen lamp 4 to form a spectrum having peaks of plural predetermined wavelengths on the linear array sensor 12. Further, the correspondence relation between wavelength and respective elements of the linear array sensor 12 is calibrated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention involves installing a standard plate on the back side of paper, irradiating light onto the surface of the paper, and introducing vertically reflected light from this time into a spectrometer. Regarding a device that detects the spectrum obtained by linear arraying and measures optical properties such as color, opacity, and whiteness of paper online, when a wavelength calibration command is given, a predetermined multiple The present invention relates to an apparatus for measuring optical properties of paper, in which a spectrum exhibiting a peak at a wavelength of is created on the linear array sensor to calibrate the correspondence between the wavelength and the linear array sensor.

[Conventional technology]

Methods for laboratory measurement of paper color, whiteness and opacity are based on the Japanese Industrial Standards, namely JI8 Z 8728, JI
8 P 8123 and JI 8 P 81sa, and the contents of the above-mentioned JIS are basically the same for devices that measure the above-mentioned optical characteristics online.

This type of conventional online measuring device has a means for directing irradiated light onto the surface of the paper to be measured at an incident angle of 45°, a spectrometer for introducing the reflected light in the vertical direction on the surface of the paper, and a spectrometer for detecting the spectrum by the spectrometer. A linear array sensor consisting of a photodiode, etc. that detects the linear
The above are often housed and installed in the same housing), white board, black board, or sample board (these are called standard boards)
and means for placing the paper in a position parallel to the back surface of the paper.

The means for installing this standard plate is usually housed in a housing installed on the O-shaped 7-frame together with a housing housing the spectrometer and linear array sensor.

Further, the two casings hold a sheet of paper, which is the object to be measured, in a facing relationship between them, and perform measurement operations while reciprocating in a section defined by the width direction of the paper.

With the above configuration K>, during measurement operation, the signal processing section:
Input the signal from the linear array sensor, JIS Z
872B, JIS P 8123 and JIS P 81
A signal corresponding to color, whiteness, and opacity is output by processing using a method similar to that specified in 75B.

[Problem that the invention seeks to solve]

However, conventional paper optical property measurement devices do not tolerate this misalignment because the misalignment of gratings, mirrors, linear arrays, etc. inside the spectrometer caused by vibrations when the housing is moved is small. However, there was a limit to the ability to improve measurement accuracy (positional deviations cause the wavelengths incident on the individual elements of the linear array sensor to change names, increasing so-called wavelength errors).

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a paper optical characteristic measuring device that performs wavelength calibration during on-twin measurement to further improve measurement accuracy.

[Means for solving problems]

The paper optical property measuring device of the present invention, which solves the above problems, uses a detection section that performs measurement operations while reciprocating in a section defined in the width direction of a sheet of paper. irradiates the surface of the paper at a predetermined angle of incidence, the reflected light in the vertical direction at this time is introduced into a spectrometer, and the spectrum created at the exit port is detected by a near array sensor. In the optical characteristic measuring device, a means for generating a wavelength calibration command at fixed time intervals or as needed, and a means for generating a wavelength calibration command on the linear array sensor based on the wavelength calibration command. and means for calibrating the correspondence between the wavelength and each element of the IJ array sensor using the detection signal of the linear array sensor.

〔Example〕

The present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing an embodiment of the present invention. The paper optical property measuring device has a detection unit 3 consisting of a housing 1 that houses an optical system etc. and a housing (not shown) that houses a holding means for a standard plate 2, and a running sheet of paper 4. A type 0 frame (not shown) that constitutes a base for reciprocating the section defined by the width direction of the paper 40, with the two casings facing each other, and a It has an arithmetic/control unit (not shown) that performs switching, signal processing from the detection unit 3, and the like. The housing 1 includes a halogen lamp 5 that irradiates the surface of the paper 4 with measurement light at an incident angle of 45 degrees, a lens 6 that collects the light reflected in the vertical direction of the paper 4, and separates the collected light into a spectrum. Spectrometer 7 (Spectrometer 7 is a mirror (concave mirror)
II. , wavelength λ
1. The linear array sensor 1 includes a mercury lamp 13 that creates calibration light having peaks at λ2 and λ5, a drive circuit for the linear array sensor 12, a signal amplification circuit, etc.
2, and a signal processing section 14 consisting of a combination 2 and 3 for determining the optical characteristics of the paper 4 by processing the detection signal from the paper 4.

As shown in FIG. 2, the linear array sensor 12 has a plurality of linearly arranged elements, for example, 1024 WA elements, whose longitudinal direction matches the wavelength distribution direction of the spectrum created by the emission aperture 11. The configuration is such that the wavelength of the spectrum corresponds to each element of the near array centimeter 12 clearly. Further, each element of the linear array sensor 12 has a unique number, for example, 1.2...
1024, and when the signal processing unit 14 inputs a detection signal from the linear array sensor 12, it is configured to clearly read and store the individual elements and signal wavelengths (the element numbered is the one detected). (The wavelength and size of the signal can be determined.) Further, as a standard plate 2, a sample plate for measuring the color and whiteness of the paper 4 (several pieces of paper cut into predetermined dimensions from the same paper as the paper 4 are stacked together);
Also, a black plate for opacity measurement (reflectance 0.5- or less)
and a white plate (reflectance of 89 cm) are prepared. Furthermore,
The holding means for the standard plate 2 holds the white plate at the traveling position (predetermined position) K of the paper 4 during calibration (no paper 4 exists between the housing 1 and the housing housing the holding means). , mercury 2 pump 1
The irradiated light from 5 is made to enter a spectrometer 7.

In the above configuration, initialization is performed to determine the correspondence between the wavelength of the spectrum created on the linear array sensor 12 and the element, and measurement begins.

Initialization is performed by the signal processing unit 14 based on the detection signal of the linear array sensor 14 when the mercury lamp 13 is turned on.
is the peak wavelength λ1. Element numbers for detecting λ2 and λ3, for example, as shown in Figure 2, , k2 and ni3
At the same time, define and store the correspondence between other elements and wavelengths, for example, the wavelength of the detection light of the number 1 element is 400 nm, the wavelength of the detection light of the number 10 element is 405 nm, etc. (if the wavelength distribution is linear) (determine the correspondence between wavelength and element).

The measurement operation is carried out by the signal from the calculation/control section, and the detection section 5
The test was carried out while the vehicle was traveling back and forth in the measurement section defined on the 0-type 7 frames. At this time, the signal processing section 14c reads the spectrum signal of the light reflected by the halogen lamp 4 from the linear array sensor 12 and stores it. Here, since the correspondence between the elements of the linear array sensor 12 and the wavelengths has been determined in the previous initialization, the spectrum signal can be accurately obtained. Then, the signal processing section 14 can obtain a desired measurement signal by using these signals and performing the same processing as in the conventional example.

On the other hand, the calibration operation is performed by moving the detection unit 5 to a calibration position (a position away from the travel path of the paper 4) according to a calibration command issued from the calculation/control unit at regular intervals. At the calibration position, the detection unit 5 installs the standard plate 2 at a predetermined position, and
The mercury lamp 13 is turned on instead of the halogen lamp 4.

As a result, the spectrum shown in FIG. 2 is created on the linear array sensor 12. The signal processing unit 14 uses the peak wavelength λ1. kll, k217, and 'Q1 of the linear array sensor 12 that detects λ2 and λ5 are determined and stored, and, assuming that the wavelength distribution is linear, the correspondence between other elements and wavelengths is defined and stored (memory (update content). Here, between the initialization and the calibration, the mirrors 11, 9
, when there is no positional shift of the grating 10 etc. or the linear array sensor 12, kl = kll, k2 = 2
1 and 5 = 31], and the memory contents remain essentially unchanged.

In addition to the above calibration, even if there is a positional shift in the mirrors 8, 9, grating 10, etc. or linear array sensor 12 between initialization and calibration, this will be compensated for and the subsequent measurement accuracy will be improved. can be improved.

The present invention is not limited to the above-mentioned embodiments. For example, instead of the mercury lamp tsK, a bandpass filter that transmits light from the mercury lamp 5 is provided, and the wavelength λ1.
Peak wavelengths corresponding to λ2 and λ3 may be created on the linear array sensor 12. Further, a command for performing calibration may be given as necessary. Furthermore, when a calibration command is given, calibration light from the mercury 2 pump 13 or pantone filter may be made to directly enter the spectrometer.

〔Effect of the invention〕

As explained above, according to the paper optical property measuring device of the present invention, the spectrum exhibits peaks at a plurality of predetermined wavelengths based on a wavelength calibration command issued at regular intervals or as needed. is created on the linear array sensor and the correspondence between the wavelength and each element of the linear array sensor is calibrated, so the measurement accuracy can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention,
FIG. 7 is a diagram showing the correspondence between a spectrum and a linear array antenna during wavelength calibration. DESCRIPTION OF SYMBOLS 1... Standard plate, 5... Detection part, 4... Sheet-like paper, 5... Halogen 2 ring, 7... Spectrometer, 8.9
...Mirror, 10...Grating, 12...
Linear array sensor, 13...Mercury 2 pump, 14...
・Signal processing section. Figure 1, 3 Figure 2

Claims (1)

[Scope of Claims] A detection unit that performs a measurement operation while reciprocating in a section defined in the width direction of a sheet of paper, which irradiates the surface of the paper with light from a light source at a predetermined incident angle, In a paper optical property measuring device equipped with a detection unit that introduces the vertically reflected light into a spectrometer and detects the spectrum created at the exit of the spectrometer using a linear array sensor, means for generating a wavelength calibration command in accordance with the wavelength calibration command, means for creating a spectrum on the linear array sensor that exhibits peaks at a plurality of predetermined wavelengths based on the wavelength calibration command, and using the detection signal of the linear array sensor. , a method for measuring the optical properties of paper, comprising means for determining the correspondence between each of the wavelengths and each element of the linear array sensor, and, based on this result, determining the correspondence between other elements and wavelengths. Device.