JP2000000960A - Content reading sensor for printed paper or the like and printed paper checking device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable each of cassettes to be positioned at a specified setting angle by forming a light source and a light receiver into a cassette shape and incorporating the cassette into a base. SOLUTION: The sensor 6 is composed of a rectangular base 10, a light source cassette 30 with an LED and a light receiver cassette 40 with a light receiving element. The light receiver cassette 40 is arranged on both sides of the light source cassette 30. The base 10 has a storage part sectioned by a partitioning and also has projecting strips on the inner face of the storage part. The light receiver cassette 40 is positioned by engaging the protrusions of the light receiver cassette 40 with the groove of the storage part. The terminal pin, of each of the cassettes 30, 40, protruding from the base 10 is connected to a terminal receiving part on a substrate. Further a void is formed between each of the cassettes 30, 40 and the partitioning and the inner face of the base 10 to dissipate heat to be generated from the cassettes 30, 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for reading the contents of an inspection surface such as a printing plate or a printing paper, and a printing paper surface inspection apparatus, wherein a light source cassette and a photoreceptor cassette are exchangeably incorporated into a base fixed to a substrate. .

[0002]

2. Description of the Related Art In a conventional printing paper surface inspection, a light receiving element such as a CCD or a photo sensor is arranged in a line in a direction orthogonal to a running direction of a printing paper, and the printing paper is scanned in a line shape sequentially to obtain a state of the paper. Is to monitor. The inspection method is to illuminate the printing paper surface with light from a light source,
Storing standard paper data without defects in the reference value memory,
Next, while storing the actual image data of the printing paper in the current value memory, the contents of the corresponding addresses of both memories are compared in synchronization with the signal from the encoder, and the printing unevenness is detected.
Various defects such as excess / deficiency of ink density, color misregistration, dirt on a part of the paper surface, and partial omission of printing have been detected.

In a sensor used for a conventional printing paper surface inspection, a light source and a light receiver are mounted on a circuit board, and the angle is adjusted. When exchanging the light source of the light source or the light receiving element of the light receiving element, the light receiving element must be set at a specified angle because the amount of light entering varies depending on the direction to the inspection surface. In particular, in the case of a line sensor configured by arranging a plurality of sensors in a line, if the mounting angle of each sensor is not constant, the amount of received light of each sensor varies, which affects the accuracy of the read content determination. For this reason, there are severe conditions such as setting each sensor at a specified angle to reduce variation in the amount of received light. Due to such restrictions, it was very difficult to accurately adjust the sensor angle at the site, so repair and element replacement at the site could not be performed, and the entire sensor unit was replaced.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sensor having a structure in which a light source body and a photoreceptor are formed into a cassette, and the cassettes are assembled into a base so that each cassette is positioned at a predetermined mounting angle. That is. Still another object is to provide a sensor that simplifies manufacturing and simplifies on-site repair and replacement. Another object of the present invention is to provide a printing paper surface inspection apparatus using the above sensor.

[0005]

Means for Solving the Problems To achieve the above object, an invention according to claim 1 is a sensor for reading contents from a printing plate or printing paper, wherein a through hole of a connection terminal is formed in a bottom. And a plurality of Ls housed in the light source case.
A light source body cassette having a light source body connection terminal for connecting to the ED and an external circuit, a light receiving element for converting light into an electric signal housed in a light receiver case, and a light body connection terminal for connecting to an external circuit. A light source cassette having a light source body cassette and a light source body cassette disposed on both sides of the light source body cassette, and a light source body connecting terminal and a light receiving body connecting terminal protruding from a through hole of the base to be connected to an external circuit. The light receiving element of the photoreceptor cassette converts light from the light source cassette reflected from the inspection surface of the printing plate or printing paper into an electric signal. According to a second aspect of the present invention, there is provided a sensor for reading contents from a printing plate or printing paper, wherein a box-shaped base having a through-hole for a connection terminal formed at a bottom and an electric circuit element housed in a light source case. A light source body cassette having a plurality of LEDs, a resistor, and a light source body connection terminal for connecting to an external circuit; a light receiving element and a resistor housed in a light receiving body case that convert light into an electric signal as an electric circuit element; A light-receiving cassette having a light-receiving body connection terminal for connection to an external circuit; a light-source body cassette provided on a base; a light-receiving body cassette disposed on both sides of the light-source body cassette; and a light-source connection terminal and a light-receiving body connection terminal Are projected from the through holes of the base and connected to an external circuit, and the light from the light source cassette reflected from the inspection surface of the printing plate or printing paper is converted into an electric signal by the light receiving element of the photoreceptor cassette.

Another invention related to the invention of claim 1 or 2 is characterized by the following constitution. (1) The LED is a white LED. (2) The light receiving element is a phototransistor. (3) Positioning portions for the light source cassette and the photoreceptor cassette are provided inside the base. (4) The light source cassette and the photoreceptor cassette each include a halved case member, a connection terminal constituting the light source cassette and the photoreceptor cassette, and an electric component element.
The connection terminal and the electric component element are accommodated in a case member, the two case members are joined together, and the joints of the case member are fused and integrated by ultrasonic waves, and at the same time, the wiring connection point between the connection terminal and the electric component element Are fused and made electrically conductive. (5) The heat dissipation hole is provided on the side surface of the case member where the resistor is arranged. (6) The base has a configuration in which partition walls are formed to form the respective accommodating portions of the light source cassette and the photoreceptor cassette. (7) An air gap is formed between the inner surface of the base, the side surface of the photoreceptor cassette facing the inner surface, and the light source cassette and the photoreceptor cassette facing each other. (8) A configuration is provided in which a partition wall is formed on the base to form the respective accommodating portions of the light source cassette and the photoreceptor cassette, and a gap is formed between the inner surface of the accommodating portion and the side surface of the light source cassette and the photoreceptor cassette. is there. (9) The gap is formed by positioning the light source cassette and the photoreceptor cassette on the base. (10) In the above-mentioned gap, the inner surface of the base, the side surface of the partition wall, the side surface of the light source cassette, and the side surface of the photoreceptor cassette face each other.
It is in a configuration formed by a void forming portion provided on at least one surface. (11) The gap forming portion has a configuration in which the light source body cassette and the photoreceptor cassette are formed as ridges extending in the direction of insertion into the base. (12) The base has a configuration provided with positioning pins for mounting on the substrate. (13) The base is provided with a surface for reflecting the light of the LED toward the inspection surface.

According to a sixteenth aspect of the present invention, when the sensor according to any one of the first to fifteenth aspects is mounted on a circuit board for reading and reading a content such as a printing paper, the base of the sensor is fixed to the board.
The light source cassette and the photoreceptor cassette are exchangeably assembled. The invention of claim 17 is based on claim 1
In the sixth aspect of the present invention, the base of a plurality of sensors is arranged in parallel on a substrate, and a light source cassette and a photoreceptor cassette are exchangeably assembled into each base to form a linear sensor.

[0008]

According to the sensor of the first and second aspects of the present invention, the photoreceptor cassette is positioned by incorporating the photoreceptor cassette into the base, and the photoreceptor can be set at a predetermined angle. In addition, the productivity is improved and the replacement work is facilitated. One light source cassette and 2
By using one photoreceptor cassette, a compact and simple structure can be achieved, the circuit configuration can be simplified, the maintenance of the device can be easily performed, and as a result, high-accuracy and high-speed measurement can be performed. In particular, according to the second aspect of the present invention, by incorporating the resistor, the circuit of the substrate is simplified, and the whole device becomes compact. In addition, since it is a circuit configuration including a resistor, a white LED is used as the LED in the cassette.
Is less likely to be affected by static electricity.
According to the invention of claims 3 and 4, L is used as the electric component element.
The use of the ED and the phototransistor makes the device compact. According to the fifth aspect of the present invention, the positioning of the light source cassette and the photoreceptor cassette in the base can be easily and reliably mounted by directing the cassette to the inspection surface, and the measurement can be started without adjustment after the mounting. be able to. According to the sixth aspect of the present invention, since the connection points of the wiring are directly fused, the occurrence of a connection failure accident like solder is small. According to the seventh aspect of the present invention, heat radiation from the resistor is positively released by providing a heat radiation hole on the side surface of the case member where the resistor is disposed, so that the semiconductor such as a phototransistor is not thermally affected. To According to the eighth to thirteenth aspects of the present invention, the light source cassette and the photoreceptor cassette are positioned with respect to the base to form a gap, thereby promoting heat release and improving reliability. According to the fourteenth aspect of the present invention, the positioning accuracy of the sensor can be enhanced by positioning the base with respect to the substrate, and adjustment for turning the LED of the light source cassette and the light receiving element of the light receiving cassette toward the inspection surface can be performed. It will be easier. According to the invention of claim 15,
By providing a reflection surface on the base, the light of the LED can be directed to the inspection surface, so that the light can be effectively used.
According to the printing paper surface inspection apparatus of claims 16 and 17,
When a plurality of sensors, in which a photoreceptor cassette is arranged with a light source cassette interposed therebetween and a plurality of sensors are arranged in a line, are used, the apparatus can be made more compact. In addition, even when printing a large amount of paper on a wide printing surface at high speed and with a large amount of printing, the deterioration of the printing state and the occurrence of dirt can be measured stably with high speed and high accuracy by using a simple apparatus configuration. In addition, the light receiving element is a photoreceptor cassette, LED
As a light source body cassette, the number of steps can be reduced, the manufacturing is simplified, and the cassette can be easily removed from the base, so that it is easy to replace / repair, especially when a line sensor is configured. This is advantageous.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the relationship between the sensor according to the present invention and a printing paper surface inspection apparatus. In the present embodiment, the inspection surface will be described by taking the paper surface of printing paper as an example. The printing paper 4 printed by the printing unit 1 including the plate cylinder 2, the blanket cylinder 3 and the like travels via the guide roller 5. A sensor 6 is arranged along the guide roller 5. The sensor 6 is arranged so that the printing paper surface can be inspected.
However, the installation location can be appropriately selected.

The printing paper surface inspection device 7 has a function of performing various printing inspections from image data of the printing paper surface read by the sensor 6. In order to read image data at a specific position on the printing paper surface, the image data is extracted by an encoder 8 that generates a pulse corresponding to the rotation of the cylinder, and the printing paper surface inspection device 7 is controlled based on the pulse signal. Here, the cylinder includes a blanket cylinder 3, a guide roller 5, and the like in addition to the illustrated cylinder 2.

As shown in FIG. 2, the sensor 6 comprises a rectangular base 10, a light source cassette 30, and two photoreceptor cassettes 4.
The photoreceptor cassettes 40 are arranged on both sides of the light source cassette 30. In FIG. 3, the light receiving element 41 of the light receiving body cassette 40 is an LED of the light source body cassette 30.
31 is illuminated, and is set in advance in a direction in which light reflected on an inspection surface such as a paper surface traveling from the right or left direction in the drawing can enter. This sensor 6 is located within the illumination range of the LED 31 with respect to the inspection surface, and the photoreceptor cassettes 4 located before and after in the traveling direction.
0 can capture information of light reflected on the same inspection surface. The line sensors are configured by arranging the sensors 6 in a line in a width corresponding to the width of the printing paper, at least a width corresponding to the inspection target range of the printing paper.

As the LED 31, a white LED having a sharp emission intensity near a wavelength of 450 nm is used, and a plurality of LEDs are arranged in a row to have a necessary light amount. Terminal pins 32 and 42 as connection terminals for the light source cassette 30 and the photoreceptor cassette 40 pass through the bottom of the base 10 and
The terminal is connected to the circuit at the upper terminal receiving portion 51. As a specific example of the terminal receiving portion 51, a socket is arranged on the substrate 50, and the terminal pins 32 and 42 are inserted into the socket and connected, or an insertion hole is provided in the substrate 50, and the terminal pin 32 is inserted into the insertion hole. , 42 are inserted and connected by soldering or the like.

FIG. 4 is a perspective view of the base, FIG. 5 is a side view, and FIG. 6 is a rear view. The base 10 has three elongated storage portions 12 formed by a partition wall 11, and each wall surface is provided with a plurality of ridges 13 extending toward the bottom. A groove 14 extending toward the bottom is provided on a wall surface in the longitudinal direction of each of the storage portions 12 except for the central storage portion 12. The side wall of the base 10 facing the partition wall 11 is the partition wall 11
An outer wall 10A protruding above the upper end surface of the outer wall 10A is provided, and an inner side of the outer wall 10A forms a reflection surface 16 inclined outward as shown in FIG. The interior of the outer wall 10A has a cavity 18 (FIG. 3, FIG.
See).

When the sensor is mounted on the apparatus, the light source cassette and the photoreceptor cassette of the sensor are stained by ink, paper dust and the like scattered from the printing paper, which hinders the paper surface inspection. In order to prevent the sensor from becoming dirty, a transparent glass is disposed between the sensor and the inspection surface, that is, on the cover constituting the sensor unit. On the other hand, since the transparent glass and the top of the outer wall of the base are disposed in contact with each other to efficiently use the reflecting surface 16, heat is easily stored in the base. As a countermeasure, in this embodiment, a space is formed between the glass and the light source and the light receiving body by the outer wall of the base, and this space is opened on the side orthogonal to the outer wall of the base. The heat generated from the light source and the light receiver is radiated through the space, thereby preventing the heat from being trapped in the base.

Holes 19 for penetrating the terminal pins 32 and 42 of the light source cassette 30 and the photoreceptor cassette 40 are formed at the bottom of the base 10, and positioning pins 20 and fixing screw holes 21 are formed at four corners on the back surface of the base 10. Each is arranged diagonally. The positioning pin 20 is provided on a pin seat 22 slightly protruding from the rear surface. The pin seat 22 forms a gap between the rear surface of the base 10 and the substrate, thereby preventing heat from being trapped by ventilation.

FIG. 7 is a perspective view of the light source cassette, FIG. 8 is a side view, and FIG. 9 is a top view. The light source cassette 30 includes a plurality of LEDs 31, resistors 34, and terminal pins 3 as electronic component elements in two divided case members 30A and 30B.
2 and the case members 30A, 30B are integrated together. The case members 30A and 30B are provided with heat radiation holes 35 for releasing heat generated from the resistor 34. The electronic component elements and the terminal pins are electrically connected by connecting the wiring connection points by ultrasonic fusion. The light source body cassette of this embodiment is provided with a pulling handle 36 for removing the light source body cassette from the base substantially at the center. Light source cassette 30
Are assembled by the ridges 13 formed on the partition wall 11 when assembled into the storage portion 12.

FIG. 10 is a perspective view of the photoreceptor cassette, and FIG.
Is a side view, and FIG. 12 is a top view. Photoreceptor cassette 40
Is basically the same as the structure of the light source body cassette 30 except that a light receiving element is used as an electronic component element. The light receiving element 41 uses a phototransistor. Here, a structural part different from the light source cassette 30 will be described. Reference numeral 44 denotes a resistor, and reference numeral 45 denotes a heat radiating hole.

A projection 43 is provided on an end surface of the photoreceptor cassette 40. The projection 43 is inserted into the groove 14 of the storage section 12, and the photoreceptor cassette 40 is positioned to thereby allow the terminal pin 42 of the photoreceptor cassette 40 to be positioned. Base 10
From the through hole at the bottom of the. When the photoreceptor cassette 40 is assembled into the storage section 12, positioning is performed between the side surface of the photoreceptor cassette 40 and the ridge 13 formed on the inner surface of the storage section 12.

The wiring for assembling the electric component elements and the terminal pins to the case member will be described. Since the wiring for mounting the light source cassette and the light receiving cassette to the case member is basically the same, a description will be given here of the wiring for mounting the light source cassette. FIG. 13 shows a state where the electric component element and the terminal pins are set on the case member.

The case members 30A and 30B are provided with places for determining the mounting positions of the electric component elements and the terminal pins. As shown in the drawing, the LED 31, the resistor 34 and the terminal pins 32 are arranged, and the wiring therebetween is provided. The light source cassette 30 is manufactured by combining the case members 30A and 30B together by ultrasonic welding to integrate the members, and at the same time, by welding and electrically connecting the connection points of the wirings.

By applying a conductive adhesive to the connection points of the wirings and then performing ultrasonic welding, a reliable electrical connection is made. The use of a conductive adhesive containing silver powder and a room temperature-curable epoxy (curing: 16 hours at 25 ° C.) confirmed a reliable electrical connection.

Next, the incorporation of the light source cassette and the photoreceptor cassette into the base will be described. In FIG. 14, the base 10 is assumed to be fixed on a substrate in advance. First, the protrusions 43 of the photoreceptor cassette 40 are inserted into the two storage portions 12 provided on both sides of the base 10 so as to match the grooves 14. In this state, the photoreceptor cassette 40 is positioned in the insertion direction, and at the same time, the projections 13 of the partition wall 11 are formed.
The terminal pins 42 protrude from the through holes at the bottom of the base and are electrically connected to the substrate since the lateral movement of both sides of the photoreceptor cassette 40 is regulated.

Thereafter, the light source cassette 30 is inserted into the central storage section 12 as shown in FIG. At this time, since the ridges 13 of the partition wall 11 regulate and position the lateral movement of both side surfaces of the light source cassette 30, the terminal pins 32 of the light source cassette 30 protrude from the through holes at the base bottom and are electrically connected to the substrate. Connected to. When exchanging the light source cassette 30 or the photoreceptor cassette 40, the corresponding cassette is pulled out from the base 10 and a new cassette is set by the above-described method.

A structure for preventing the heat generated from the resistor from being trapped in the base 10 during use of the sensor and having a thermal effect on the light receiving element will be described. A gap is provided between the inner surface of the storage section 12 of the base 10 and the side surfaces of the light source cassette 30 and the photoreceptor cassette 40, and the gap radiates heat. The gap is the ridge 13 described in the above embodiment, that is,
It is formed by providing the ridge 13 on the inner surfaces of the partition wall 11 and the side wall of the base 10 or by providing the ridge 13 on the side surface of the cassette. Further, instead of the ridge 13, a projection having a predetermined length may be used.

In another modification, the base 10 can be configured to position the photoreceptor cassette 40 with respect to the storage section 12.
A gap may be formed between the inner surface of the side wall and the inner surface of the partition wall 11. In this case, a gap can be formed between the light source body cassette 30 and the inner surface of the partition wall 11 by providing the light source body cassette 30 with the same positioning means as the light receiving body cassette 40.

Although the above-described heat dissipation structure has been described by using the base 10 having the partition wall 11, even in the structure without the partition wall 11, the space between the light source cassette 30 and the photoreceptor cassette 40, the inner surface of the photoreceptor cassette 40 and the side wall of the base 10, An air gap required for heat dissipation can be formed between them. In the specific example, a concave portion or a convex portion is provided on the inner surface of the base side wall in the cassette insertion direction, and a convex portion is provided on one cassette side with respect to the concave portion on the base side or a concave portion with respect to the convex portion.

The cassette is positioned with respect to the base by engagement of the projections and recesses of these members to form a predetermined gap between the light source cassette and the photoreceptor cassette and between the photoreceptor cassette and the inner surface of the side wall of the base. I do. As another structure, a space is formed by a protrusion or the like on the side surface of the cassette, and the protrusion is applied to the opposing side surface of the cassette and the inner surface of the base side wall to form a space between both members. By combining the configurations described in the above embodiments, the positioning of the light source cassette and the photoreceptor cassette with respect to the base and the heat radiation effect of the cassette can be enhanced.

In the above embodiment, the partition wall is provided with a ridge. However, the positioning means has a function of forming a gap between the members by positioning, so that the ridge is formed on the inner surface of the base and the side of the partition wall. Can be adopted. Further, when the resistor is not built in the cassette, since no heat is generated inside the cassette, the heat radiation hole may not be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a sensor according to the present invention and a printing paper surface inspection apparatus.

FIG. 2 is an assembly view of a sensor.

FIG. 3 is an explanatory diagram showing a relationship between a sensor and a substrate.

FIG. 4 is a perspective view of a base.

FIG. 5 is a side view of a base.

FIG. 6 is a rear view of the base.

FIG. 7 is a perspective view of a light source cassette.

FIG. 8 is a side view of the light source cassette.

FIG. 9 is a top view of the light source cassette.

FIG. 10 is a perspective view of a photoreceptor cassette.

FIG. 11 is a side view of the photoreceptor cassette.

FIG. 12 is a top view of the photoreceptor cassette.

FIG. 13 is an explanatory diagram of an assembly wiring.

FIG. 14 is an explanatory view showing the incorporation of a photoreceptor cassette into a base.

FIG. 15 is an explanatory diagram showing the incorporation of the light source cassette into the base.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printing unit 2 Plate cylinder 3 Blanket cylinder 4 Printing paper 5 Guide roller 10 Base 30 Light source body cassette 31 LED 40 Photoreceptor cassette 41 Light receiving element 50 Substrate

Claims (17)

[Claims] 1. A sensor for reading contents from a printing plate or printing paper, comprising: a box-shaped base having a through-hole of a connection terminal formed at a bottom; a plurality of LEDs and an external circuit housed in a light source case; Light source cassette having a light source connection terminal for connecting to a light source, a light receiving unit cassette having a light receiving element for converting light into an electric signal, and a light receiving body connection terminal for connecting to an external circuit, housed in a light receiving case. A light source body cassette and a light receiving body cassette disposed on both sides of the light source body cassette on the base, and a light source body connecting terminal and a light receiving body connecting terminal projecting from a through hole of the base and connected to the external circuit. And a light receiving element of the light receiving cassette converts the light reflected from the inspection surface of the printing plate or printing paper from the light source cassette into an electric signal. 2. A sensor for reading contents from a printing plate or printing paper, comprising: a box-shaped base formed with a through hole of a connection terminal at a bottom; and a plurality of electric circuit elements housed in a light source case. A light source body cassette having a light source body connection terminal for connecting to an LED, a resistor, and an external circuit, a light receiving element for converting light into an electric signal as an electric circuit element, a resistor, and an external circuit housed in a light receiving body case A light source cassette having a light source connection terminal for connecting to the light source body; and a light source body cassette and a light source body cassette disposed on both sides of the light source body cassette on the base, and a light source body connection terminal and a light body connection terminal. The light from the light source cassette reflected from the inspection surface of the printing plate or printing paper is converted into an electric signal by the light receiving element of the light receiving cassette by projecting from the through hole of the base and connecting to the external circuit. Sensor according to claim. 3. The sensor according to claim 1, wherein the LED is a white LED. 4. The sensor according to claim 1, wherein the light receiving element is a phototransistor. 5. The sensor according to claim 1, wherein a positioning portion for the light source cassette and the photoreceptor cassette is provided inside the base. 6. The sensor according to claim 1, wherein the light source cassette and the photoreceptor cassette each comprise a split case member, a connection terminal forming the light source cassette and the photoreceptor cassette, and an electric component element. The connection terminal and the electric component element are accommodated in a case member, the two case members are joined together, and the joints of the case member are fused and integrated by ultrasonic waves, and at the same time, the wiring connection point between the connection terminal and the electric component element A sensor characterized by being fused and electrically connected. 7. The sensor according to claim 2, wherein a heat radiating hole is provided on a side surface of the case member where the resistor is arranged. 8. The sensor according to claim 1, wherein the base is provided with a partition wall that forms a housing portion for each of the light source cassette and the photoreceptor cassette. 9. The sensor according to claim 1, wherein a gap is formed between an inner surface of the base and a side surface of the photoreceptor cassette opposed to the inner surface, and a side surface of the light source cassette and the photoreceptor cassette facing each other. A sensor characterized by the above-mentioned. 10. The sensor according to claim 1, wherein a partition wall is formed on the base to form a housing for the light source cassette and the light receiving cassette, and the inner surface of the housing and the light source cassette and the light receiving cassette are separated from each other. A sensor, wherein a gap is formed between the sensor and a side surface. 11. The sensor according to claim 9, wherein the air gap is formed by positioning the light source cassette and the photoreceptor cassette on a base. 12. The sensor according to claim 9, wherein the air gap is formed on at least one surface of the inner surface of the base, the side surface of the partition wall, the side surface of the light source cassette, and the side surface of the photoreceptor cassette. A sensor characterized by being formed by: 13. The sensor according to claim 12, wherein the gap forming portion is formed by a ridge extending in a direction in which the light source cassette and the photoreceptor cassette are inserted into the base. 14. The sensor according to claim 1, wherein the base includes a positioning pin for mounting on the substrate. 15. The sensor according to claim 1, wherein the base has a surface for reflecting the light of the LED toward the inspection surface. 16. A light source cassette and a photoreceptor cassette when a sensor according to any one of claims 1 to 15 is mounted on a circuit board for discriminating content reading such as a printing paper surface, the base of the sensor is fixed to the substrate. A content reading discrimination device characterized by incorporating a replaceable. 17. The content reading determination device according to claim 16, wherein bases of a plurality of sensors are arranged in parallel on a substrate, and a light source cassette and a photoreceptor cassette are interchangeably incorporated into each base to form a linear sensor. A content reading discrimination device characterized in that: