JPH01140855A - Shading inspection system using test chart - Google Patents

Abstract

PURPOSE:To measure the evenness and the level of shading by a recorded picture by making a test chart have a pattern whose gradation is constant in a main scanning direction and varies from white to black in a subscanning direction. CONSTITUTION:The pattern is formed on the test chart by being printed on wood free paper of being exposed on photographic paper. The pattern has the constant gradation in the main scanning direction X, and the density of it varies continuously or stepwise from white to black in the subscanning direction Y.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a test chart, and more particularly, to the inspection of shading in facsimile machines, g-copiers, and other similar devices that have a scanner that reads two-dimensional image information using a line scanner. Regarding method 1c.

2. Description of the Related Art Conventionally, the shading of this type of scanner has been inspected by measuring the 4-channel signal from the scanner using an oscilloscope or the like.

Problems to be Solved by the Invention According to the conventional scanner shading inspection method described above, the shading signal of the scanner is measured by a measuring instrument, so there is a drawback that a specific measuring instrument is required. There is a drawback that inspection requires a large amount of man-hours, such as disassembling the cover of the screen to expose the terminals.

The present invention has been made in view of the above-mentioned conventional situation,
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thorough shading inspection method that makes it possible to eliminate the above-mentioned drawbacks inherent in the conventional techniques.

Means for Solving the Problems In order to achieve the above object, the shading inspection method using a test chart according to the present invention uses a scanner that reads two-dimensional image information using a line sensor, and a constant gradation in the main scanning direction. , and a test chart characterized by having a gradation pattern that changes from white to black in the sub-scanning direction.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

FIG. 7 is a diagram showing a test chart according to the present invention.

The test chart has a pattern as shown in the figure printed on high-quality paper or exposed to light on white paper. This pattern has a constant gradation in the main scanning direction X shown in the figure, and the density changes continuously or stepwise from white to black in the sub-scanning direction Y.

FIG. 1 is a schematic configuration diagram of a scanner that is a target of the inspection method according to the present invention.

Referring to FIG.
is sent in the direction of arrow A. Original l is illuminated at reading line q -ft! The image is irradiated with light by the lens B, and is reduced and projected onto the line sensor 7, and the licensor 7 generates an image signal of the original l to the image signal processing circuit g. Image signal processing circuit t.

The line sensor 7 is driven at a constant timing to perform main scanning, and the feed roller pair 2.3 is driven at a constant timing to perform sub-scanning. Also.

The image signal that has been appropriately processed by the image signal processing circuit j is sent to the printer, and a recording surface that is the same as the original l is obtained by the printer.

FIGS. 3 to 6 show examples of shading signal waveforms obtained by the line sensor when reading a white original and the recording surface in each case.

FIGS. 3(a) and 3(b) show normal shading signal waveforms and recording surfaces. Since the shading signal waveforms shown in FIGS. 3A and 3B have been adjusted for shading so as to completely exceed the black and white threshold level A, the recording surface shown in FIG. 3B reproduces a white original well.

Figures (a) and (b) show the shading waveform and recording surface when shading is applied to lower the overall signal level. Since the shading signal waveform is F around the black-and-white threshold level A, the recording surface becomes completely black and there is no reproducibility of a white original.

FIGS. 5(a) and 5(b) show shading waveforms and recording surfaces when shading adjustment is performed such that the left and right signal levels are lowered. Since the left and right portions of the shading signal waveform are below the black-and-white threshold A, the left and right portions of the recording surface in the main scanning direction are black, and the reproducibility is not good.

FIGS. 84(a) and 84(b) show the shading waveform and recording surface when shading adjustment is made such that the signal level in the center becomes low. Since the central portion of the shading signal waveform is below the black-and-white threshold A, the central portion of the recording surface becomes black and the reproducibility is poor.

FIGS. 7(a) and 7(b) show test charts of the present invention, and the recording surface after the shading adjustment shown in FIG. 3 is shown. The shading is flat and the signal level is appropriate, so the recording surface switches between black and white at approximately the middle density of the original.

Figures (a) and (b) show the recording surface when the test chart of the present invention is used and the shading adjustment shown in Figure 1 is applied. Although the shading is flat.

Since the signal level is low, the black and white switching point on the recording surface is closer to the white side (K) than in FIG.

FIGS. 7(a) and 7(b) show test charts of the present invention, and FIG. S shows the recording surface when the shading adjustment has been made. Since the shading is depressed at both ends, the recording surface becomes as shown in FIG. 9(b).

The test chart fr of the present invention is shown in FIGS. 1O(a) and (b).
, shows the recording surface when the shading adjustment shown in FIG. 6 has been performed. Since the shading is depressed in the center, the recording surface becomes as shown in FIG. 10(b).

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a test chart having a pattern of constant gradation in the main scanning direction and a gradation pattern that changes from white to black in the sub-scanning direction is read with a scanner,
By obtaining the recording surface, the flatness and level of shading can be measured on the recording surface without using a measuring device.

[Brief explanation of the drawing]

Side 1 is a fatigue diagram of the test chart according to the present invention,
Figure 1 is a schematic view of the # side of the scanner that is the subject of the test food of the present invention, Figures 3 (a), (b) to Figure 6 ra), (b)
Figures 7(a), (b) to 70(a) are diagrams showing signal waveforms and white manuscript recording images during shading adjustment of Dannan.
. (b) is a diagram showing completed images of the test chart according to the present invention at the time of various shading adjustments. /... Haraura, Ko, 3... Feed roller pair, II.
...reading line, j...illumination f, 6...lens, ri...line sensor, t...image signal processing circuit, 9
...Printer patent applicant NEC Co., Ltd. Representative Patent attorney Yuta Kumatani Chief owner of a limited amount of information > Signal Namigata &
! Manga (Ql)
Ibl Figure 3 Main Quantification〉Etende Signal Type 1
Recording image (01 Ibl Figure 4 11 1') 67- Main Quantification Sheet) Sign 1g Waveform
Note tk1.1real
(bl Fig. 5 1 running distance Ni Erann)
;i 1 country k [tel
, +bl Figure 6 manuscript note 11th stroke +a+ (bl No. 7
Diagram Original: Kenji fat (bl Figure 8 Tiger Manuscript [01 1st manuscript recording side + b1 9 Figure 10)

Claims (1)

[Claims] A shading inspection method for a scanner that reads two-dimensional image information using a line sensor, characterized by having a pattern of gradation that is constant in the main scanning direction and changes from white to black in the sub-scanning direction. Shading inspection method using test chart.