JPH05307008A - Print surface monitoring device - Google Patents

Abstract

PURPOSE:To enhance the monitoring accuracy of a printing surface by making such a weighting that the output value(s) of an adjoining photo-receiving element or elements is (are) added to the output value of each photo-receiving element, and eliminating the bottom of sensitivity in sensing. CONSTITUTION:In a printing surface monitoring device 10, the output signal V2a, V2b from photo-receiving elements (a, b)... of a sensor arranged perpendicular to the feeding direction of a printing surface are passed to a monitoring circuit 13. The circuit 13 makes comparison with the set reference level, and if it exceeds an allowable value, an error signal is sent to an alarm 14 to issue alarm. If therein the output voltage V1b of an amplifier 21 of the corresponding amplifier circuit 20b is impressed on the photo-receiving element (b) adjacent through a resistance R1b to the input side of an amplifier 22 of the corresponding amplifier circuit 20a to the photo-receiving element (a), the output voltage V2a of the amplifier 22 becomes V2a=(R2a/R1a)XV1a+(R2a/R1a)X-V1. If the resistance value R2a is set equal to R1b, that is to say, the output value of the adjacent photo-receiving element (b) is added as it is to the output value of the photo-receiving element (a), so that the difference in sensitivity between the center and periphery of element can be corrected using a simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing surface monitoring apparatus suitable for inspecting the printing condition of a printing surface.

[0002]

2. Description of the Related Art Conventionally, as a printing surface monitoring apparatus, Japanese Patent Laid-Open No.
There is one as described in Japanese Patent No. 153944. This conventional technique has an illuminating device that emits light to a printing surface that is fed in one direction, and a plurality of light receiving elements that are arranged in a line in a direction orthogonal to the feeding direction of the printing surface. And a monitoring device for monitoring the printing state of the printing surface based on the output signal from each light receiving element of the detector.

That is, the printing surface monitoring device, when feeding the printing surface, sequentially processes the output signals of the respective light receiving elements of the detector by the monitoring device, line by line in the direction orthogonal to the feeding direction of the printing surface. However, the entire printed surface can be inspected.

Here, the detector amplifies the photocurrent obtained from each of the light receiving elements a, b ... With the amplifier circuits shown in FIG. 4 by the amplifiers 1 and 2, and outputs an output voltage corresponding to the density of the printing surface. V _2a = (R _2a / R _1a ) V _1a is output. V _1a is the output voltage of the amplifier 1, and R _1a and R _2a are resistance values.

However, the sensitivity of each light receiving element constituting the detector has a peak on the center line of the light receiving element as shown in FIG. For this reason, the detection sensitivity of the detector including a plurality of light receiving elements arranged in a line is as shown in FIG. 5B, and a valley of the sensitivity is generated in the middle corresponding portion of each light receiving element. For this reason, if a defective portion on the printed surface exists corresponding to the above-mentioned valley of the sensitivity of the detector, the defective portion becomes difficult or impossible to detect.

Therefore, in the above-mentioned conventional technique, in order to eliminate the above-mentioned valley of the sensitivity of the detector, the adjacent portions of the adjacent light receiving elements are arranged so as to overlap each other in the feeding direction of the printing surface.

[0007]

However, in the prior art, it is necessary to change the form of the light receiving element in order to eliminate the valley of the sensitivity of the detector, and the configuration becomes extremely complicated.

The present invention relates to a printed surface monitoring apparatus using a detector in which a plurality of light receiving elements are arranged in a line, and it is possible to improve the monitoring accuracy by eliminating the valley of the sensitivity of the detector with a simple structure. To aim.

[0009]

According to the present invention, there is provided an illuminating means for irradiating a printing surface which is fed in one direction with light, and a plurality of illuminating means arranged in a line in a direction orthogonal to the feeding direction of the printing surface. In the printing surface monitoring device having a light receiving element for detecting the amount of light reflected from the printing surface, and a monitoring means for monitoring the printing state of the printing surface based on the output signal from each light receiving element of the detection means, The light receiving amount correcting means is provided for setting a value obtained by adding the output value of at least one light receiving element adjacent to this light receiving element to the output value of the light receiving element itself as an output signal from this light receiving element. It is a thing.

[0010]

The output signal from each light receiving element becomes a value obtained by adding the output value of the light receiving element itself to the output value of another light receiving element adjacent to the light receiving element. That is, the decrease in sensitivity at the peripheral portion on the side of the center line of each light receiving element is compensated for between the adjacent light receiving elements (see FIGS. 2A and 2B).

Therefore, the detection sensitivity of the detector including the respective light receiving elements becomes uniform as shown in FIG. 2C in the direction orthogonal to the feeding direction of the printing surface.

[0012]

1 is a detection signal processing circuit diagram showing an example of a printing surface monitoring device, FIG. 2 is a sensitivity distribution diagram of a detector, and FIG. 3 is a schematic diagram showing an example of a printing surface monitoring device.

As shown in FIGS. 1 and 3, the printing surface monitoring device 10 comprises an illuminating device 11, a detector 12, and a monitoring circuit 13.

The illuminating device 11 irradiates the printing surface 30 fed in one direction with light. The illumination device 11 is composed of, for example, a cylindrical fluorescent lamp extending in a direction orthogonal to the feeding direction of the printing surface 30.

The detector 12 has a plurality of light receiving elements (photodiodes, CCDs, etc.) a, b, ... Arranged in a line in a direction orthogonal to the feeding direction of the printing surface 30. The amount of reflected light is detected.

The monitoring circuit 13 includes each light receiving element of the detector 12.
Output signals from a, b ... (V_2a, V _2bBased on…)
The printing state of the printing surface 30 is monitored.

That is, the printing surface monitoring apparatus 10 includes a printing surface 30
, The output signals (V _2a , V _2b, ...) Of the light receiving elements a, b ... Of the detector 12 are sequentially monitored by the monitoring circuit 13 line by line in the direction orthogonal to the feeding direction of the printing surface 30. Signal processing is performed so that the entire printed surface 30 can be inspected. Then, the monitoring circuit 13 controls the light receiving elements a and b of the detector 12.
Output signal is compared with a predetermined reference level, and when the difference between the output signal and the reference level exceeds a predetermined allowable value, the surface to be inspected corresponding to the output signal is defective. The judgment is made, an error signal is sent to the alarm 14, and an alarm is issued.

Here, the detector 12 includes the light receiving elements a and b.
An independent optical path tube 15 is defined for each of the light receiving elements a, and only the amount of reflected light from the inspection area defined on one line of the printing surface 30 is determined for each light receiving element a,
The light is received by b ... and the photocurrents are generated in the respective light receiving elements a, b.

The detector 12 includes the light receiving elements a and b.
The photocurrent obtained from each of the amplifier circuits 20 shown in FIG.
a, 20b ... Amplified by the amplifiers 21 and 22, and output voltages V _2a , V _2b, ... Depending on the density of the printing surface 30.
Is output.

However, in the detector 12, the output values of the individual light receiving elements a, b ...
A value that takes into account the output values of the light receiving elements b, c, which are adjacent to
A light receiving amount correcting means for outputting the output signals from the light receiving elements a, b ... Is provided.

In this embodiment, as a concrete example of the above-mentioned light receiving amount correcting means, the amplifier circuits 20a ... Corresponding to the light receiving elements a ...
The entry side of the amplifier 22 via the resistance R _1b, the amplifying circuit 20b corresponding to adjacent light receiving elements b ... ... amplifier 21
The output voltage V _1b is applied. According to this
The output voltage V _2a of the amplifier 22 of the amplifier circuit 20a corresponding to the light receiving element a is expressed by the following equation (1).

[0022]

[Equation 1] V _1a is the output voltage of the amplifier 21 of the amplifier circuit 20a, R _1a ,
R _2a is the resistance value of the amplifier circuit 20a. The first term on the right side of the equation (1) is the output value of the light receiving element a itself when there is no received light amount correction means, and the second term on the right side is the added value by the received light amount correction means.

In the above-mentioned light receiving amount correcting means, R _1b
= R _1a ,

[Equation 2] Therefore, the output values of the adjacent light receiving elements b are simply added as they are.

However, in the embodiment of the present invention, an arbitrary% of the output values of the adjacent light receiving elements b may be added. When 50% of the output value of the adjacent light receiving element b is to be added, R _1b = 2R _1a may be set.

The operation of this embodiment will be described below.
In the detector 12, the output signals from the respective light receiving elements a, b ... Are added to the output values of the light receiving elements a, b. The output value of c ... Is taken into consideration. 2 (A) is, the light receiving elements a output value of itself _{(R 2a / R 1a) V} 1a = S a, the additional value based on the output value of the adjacent light-receiving elements _{b (R 2a / R 1b)} V 1b = S
It is the sensitivity of the light receiving element a, which is the result of adding _ab . Further, FIG. 2B shows the output value (R _2b / R 2) of the light receiving element b itself.
_1b ) V _1b = S _b , which is the result of adding the added value (R _2b / R _1c ) V _1c = S _bc based on the output value of the adjacent light receiving element c, which is the sensitivity of the light receiving element b. That is, each light receiving element a, b
The decrease in sensitivity at the peripheral portion on the side of the center line of ... Is compensated for between the adjacent light receiving elements.

Therefore, the detection sensitivity of the detector 12 including the light receiving elements a, b, ... Is uniform in the direction orthogonal to the feeding direction of the printing surface 30 as shown in FIG.

Therefore, the valley of the sensitivity of the detector 12 can be eliminated by a simple structure in which the outputs of the light receiving elements a, b ... Are only electrically processed. Therefore, even when the defective portion of the printing surface 30 is present in the intermediate corresponding portion of the light receiving elements a, b, ... Which are adjacent to each other, the defective portion can be reliably detected and the monitoring accuracy can be improved.

In the implementation of the present invention, the received light amount correction means adds the output value of each light receiving element itself to the output value of each one light receiving element adjacent on both sides of this light receiving element. It is possible to add two or more output values adjacent to the light receiving element.

[0029]

As described above, according to the present invention, in a printed surface monitoring apparatus using a detector in which a plurality of light receiving elements are arranged in a line, the structure is simplified and a valley in the sensitivity of the detector is eliminated. , The monitoring accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a detection signal processing circuit diagram showing an example of a printing surface monitoring apparatus.

FIG. 2 is a sensitivity distribution diagram of a detector.

FIG. 3 is a schematic diagram illustrating an example of a printing surface monitoring device.

FIG. 4 is a diagram of a conventional detection signal amplifier circuit.

FIG. 5 is a sensitivity distribution chart of a conventional detector.

[Explanation of symbols]

 10 Printing Surface Monitoring Device 11 Illumination Device 12 Detector 13 Monitoring Circuit 30 Printing Surface a, b, c ... Light receiving element

Claims (1)

[Claims] 1. A printing surface comprising: an illuminating means for irradiating a printing surface, which is fed in one direction, with light; and a plurality of light receiving elements arranged in a line in a direction orthogonal to the feeding direction of the printing surface. In a printing surface monitoring device having a detecting means for detecting the amount of reflected light of the light receiving element and a monitoring means for monitoring the printing state of the printing surface based on the output signal from each light receiving element of this detecting means, the output value of each light receiving element itself , A value considering the output value of at least one light receiving element adjacent to this light receiving element,
A printing surface monitoring apparatus comprising a light receiving amount correcting means for outputting an output signal from the light receiving element.