JP2019219190A - Measuring device, image forming device, and measuring method - Google Patents

Abstract

To accurately predict the weight per unit area of printing paper.SOLUTION: A measuring device (10) includes a light source (1), a light receiving unit (2), a light limiting unit (3) for limiting light received by the light receiving unit (2), and a CPU (4). The CPU (4) calculates the grammage of printing paper (P) on the basis of the amount of light applied to the printing paper (P) from the light source (1) and the amount of light received by the light receiving unit (2).SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a measurement apparatus, an image forming apparatus, and a measurement method that measure absorbance of an object such as printing paper and measure predetermined characteristics of the object from the absorbance.

  In an image forming apparatus such as a copying machine, in order to appropriately form an image on print paper, it is necessary to make settings according to the type and thickness of the print paper. Therefore, in order to determine the type and thickness of the printing paper, the basis weight of the printing paper is predicted as a setting item before image formation. Here, the prediction of the basis weight of the printing paper is a process for calculating the weight (basis weight) per unit area of the printing paper.

  The basis weight prediction in the image forming apparatus is often performed by measuring the absorbance of the printing paper. The absorbance is calculated using, for example, the Lambert-Beer equation. Specifically, the absorbance of the printing paper is calculated based on the amount of light irradiated on the printing paper and the amount of transmitted light transmitted through the printing paper, and the unit of the printing paper is calculated based on the calculated absorbance. The weight per area is estimated.

  Examples of techniques for determining the type and thickness of print paper using light include Patent Documents 1 to 3. In Patent Document 1, after printing paper is pulled out from a paper feed tray before printing is started and stopped, light transmitted through the printing paper is detected by a light transmission type sensor that forms an optical axis crossing the printing paper, and the amount of light is detected. A paper type determination method for determining the type of printing paper from a corresponding voltage is disclosed. Patent Document 2 discloses an apparatus that detects double feeding of paper sheets based on the diffusion distribution of transmitted light of the paper sheets being conveyed. Patent Literature 3 includes a light source unit that irradiates a recording medium with irradiation light of a different wavelength or wavelength region, and a light receiving unit that receives transmitted light having the irradiation light transmitted through the recording medium. An image forming apparatus that determines the thickness of a recording medium based on a difference in the amount of received light has been disclosed.

JP-A-7-196207 (published August 1, 1995) JP 2001-341895 A (published December 11, 2001) JP-A-2017-102046 (published on June 8, 2017)

  In the conventional basis weight prediction, as shown in FIG. 9, a light emitting element that irradiates light to printing paper and a light receiving element that receives transmitted light transmitted through the paper are arranged such that their optical axes are substantially coincident with each other. Is done. This is because when calculating the absorbance of printing paper using the Lambert-Beer equation, the optical axis of the light-emitting element and the optical axis of the light-receiving element must be almost the same in order to accurately measure the absorbance of the printing paper. This is because it is desirable.

  However, the absorbance of the printing paper is affected by the degree of light scattering within the printing paper. That is, even if the printing paper has the same basis weight, when the scattering of light in the printing paper is large, the amount of transmitted light transmitted through the printing paper is small, and when the scattering of light in the printing paper is small. In this case, the amount of transmitted light transmitted through the printing paper increases. Therefore, when the basis weight is estimated using the light emitting element and the light receiving element arranged as shown in FIG. 9 on the printing paper having different degrees of light scattering in the printing paper, it may not be possible to determine correctly. There is.

  Depending on the brand of the printing paper, the type and amount of the filler and the paper strength agent used may be different. In such a case, the degree of light scattering in the printing paper is different for each brand. Here, the filler is added to improve the smoothness, opacity, color tone, printability and the like of the paper, and examples thereof include clay, talc, and calcium carbonate. The paper strength enhancer is a chemical added to enhance the strength of paper, and includes, for example, starch and polyacrylamide-based polymers. The paper strength is a property of the paper evaluated based on evaluation criteria such as burst strength and internal bond.

  For example, when the technique disclosed in Patent Document 1 is applied to the basis weight prediction, since the light transmitted through the printing paper is not affected by the degree of light scattering in the printing paper, accurate There is a problem that it is difficult to predict a proper basis weight.

  Further, when the techniques disclosed in Patent Documents 2 and 3 are applied to the basis weight prediction, there is a problem that an increase in cost cannot be avoided. Specifically, in the technique disclosed in Patent Document 2, it is necessary to introduce a plurality of light-emitting elements and light-receiving elements, and in the technique disclosed in Patent Document 3, irradiation light of different wavelengths or wavelength regions is used. It is necessary to provide a laser capable of irradiating a recording medium and a plurality of light receiving elements.

  One aspect of the present disclosure is a measuring device that accurately measures a predetermined characteristic of an object, even when the degree of light scattering of an object such as printing paper is different while suppressing an increase in cost, an image forming apparatus, And a measurement method.

  In order to solve the above-described problems, a measurement device according to an embodiment of the present disclosure includes a light source that emits light to irradiate an object, a light receiving unit that receives transmitted light from the object, and the light that is transmitted toward the light receiving unit. A light restricting unit that restricts a part of light, and a measuring device including: a position where an optical axis of the light source intersects with the object; and a normal passing through a center of a light receiving surface of the light receiving unit. The intersection is at a predetermined distance from the intersection, and a calculation unit that calculates predetermined characteristics of the object based on the amount of light emitted from the light source to the object and the amount of light received by the light receiving unit. Is further provided.

  In order to solve the above problem, a measurement method according to an aspect of the present disclosure includes a light irradiation step of irradiating an object with light from a light source, and a light restricting unit that restricts a part of transmitted light from the object. A light receiving step of receiving the passed light by a light receiving unit, wherein the position at which the optical axis of the light source intersects the object and the normal passing through the center of the light receiving surface of the light receiving unit are the object. Is located at a predetermined distance from the light source, and calculates a predetermined characteristic of the object based on the amount of light emitted from the light source to the object and the amount of light received in the light receiving step. The method further includes a calculating step.

  According to an aspect of the present disclosure, it is possible to accurately measure a predetermined characteristic of an object such as a printing paper even if the printing paper has a different degree of light scattering within the printing paper while suppressing an increase in cost. it can.

FIG. 1 is a diagram illustrating an example of a main configuration of a measurement device according to an embodiment of the present disclosure. FIG. 4 is a diagram illustrating that the intensity of light transmitted through the printing paper and the spread of the diffusion region are different depending on the degree of scattering of light in the printing paper. It is a figure showing the example of the opening which a light restricting part has. FIG. 2 is a block diagram illustrating a configuration example of an image forming apparatus including a measuring device. 9 is a flowchart illustrating an example of a processing flow of the image forming apparatus including the measurement device. It is sectional drawing which shows another example of arrangement | positioning of a light source and a light receiving part. It is sectional drawing which shows the other example of arrangement | positioning of a light source and a light receiving part. It is sectional drawing which shows the other example of arrangement | positioning of a light source and a light receiving part. FIG. 7 is a diagram illustrating results demonstrating the effectiveness of the measurement method according to an embodiment of the present disclosure. It is a figure in the conventional basis weight prediction which shows the example of arrangement | positioning of the light emitting element and the light receiving element.

[Embodiment 1]
The measuring device 10 according to an aspect of the present disclosure includes a light source 1 that emits light to irradiate an object, a light receiving unit 2 that receives transmitted light from the object, and a light that limits a part of the transmitted light directed to the light receiving unit 2. A limiting unit 3. The measuring device 10 is a device that calculates a predetermined characteristic of an object based on the amount of light emitted from the light source 1 to the object and the amount of light received by the light receiving unit 2. Here, a description will be given by taking as an example the printing paper P that is the paper to be printed as the object to be weighed, but the object is not limited to this. For example, the measuring device 10 can be applied to various objects such as cloth, resin products, and sheets. The measuring device 10 is a device that calculates at least one of the basis weight, the scattering coefficient, and the anisotropic scattering parameter of the object as the predetermined characteristics. Further, the measuring device 10 may be configured to specify the type of the printing paper P based on at least one of the calculated basis weight, scattering coefficient, and anisotropic scattering parameter of the object.

  Hereinafter, an embodiment of the present disclosure will be described in detail.

(Configuration of measuring device 10)
First, the configuration of the measuring device 10 will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a main configuration of a measuring device 10 according to the present embodiment.

  The measuring device 10 includes a light source 1, a light receiving unit 2, a light limiting unit 3, and a CPU 4 (calculating unit). The measuring device 10 further includes a constant current source 5, a variable resistor 6, an amplifier circuit 7, and an A / D converter 8.

  The light source 1 is typically a light emitting element and emits light for irradiating the printing paper P. Light emitted from the light source 1 to the printing paper P has a constant irradiation angle θ, and the irradiation angle θ is desirably 50 to 70 °. Here, the irradiation angle θ of the light source 1 intends an angle at which light can be emitted from the light source 1. The intensity of light emitted from the light source 1 is high on the optical axis L1, and decreases as the irradiation angle θ increases. In general, the irradiation angle θ of the light source 1 is represented by an angle from the light intensity on the optical axis L1 until the light intensity decreases by a fixed ratio (for example, 50%). Here, when the shape of the light source 1 has a curved portion, the “optical axis” of the light source 1 means a normal extending from the light emission center of the light source 1. The normal extending from the light emission center of the light source 1 may include a perpendicular line perpendicular to the light source 1.

  In addition, the light source 1 may emit light radially from the light emission central portion, or may emit parallel light from the light emission central portion.

  The light receiving unit 2 is typically a light receiving element, and receives light in the diffusion region B of light transmitted through the printing paper P. The light receiving unit 2 is located at a position off the optical axis L1 of the light source 1. Are arranged to be located. In other words, the light receiving unit 2 is arranged so as to have a peak of the light receiving sensitivity with respect to the transmitted light at a position deviated from the optical axis L1 of the light source 1. The light receiving angle of the light receiving section 2 is desirably 50 to 70 °. In the example shown in FIG. 1, the center of the light emitted from the light source 1 matches the optical axis L1 of the light source 1, and the center of the light receiving angle of the light receiving unit 2 matches the optical axis L2 of the light receiving unit 2. ing. The light receiving angle is intended to mean an angle at which the light receiving unit 2 can receive incident light. The light receiving sensitivity of the light receiving unit 2 is high on the optical axis L2, and decreases as the light receiving angle increases. The light receiving angle of the light receiving unit 2 is represented by an angle at which the sensitivity is reduced by a fixed rate (for example, 50%) from the light receiving sensitivity on the optical axis L2. In addition, although described above as the optical axis L2 of the light receiving unit 2, the normal passing through the center of the light receiving surface of the light receiving unit 2 is expressed as "optical axis" for convenience. The normal passing through the center of the light receiving surface of the light receiving unit 2 may include a perpendicular line passing through the center of the light receiving surface of the light receiving unit 2 and perpendicular to the light receiving unit 2. The center of the light receiving surface is intended to be a position having the highest light receiving sensitivity. For example, when the light receiving surface is circular, it is the center of the circle. As shown in FIG. 1, the position where the optical axis L1 of the light source 1 intersects the printing paper P and the position where the normal (optical axis L2) passing through the center of the light receiving surface of the light receiving unit 2 intersects the printing paper P are as follows. , A predetermined distance D1.

  The light restricting unit 3 restricts a part of light that is transmitted through the printing paper P and diffused, and is directed to the light receiving unit 2. The light restricting unit 3 is a light-blocking member, and blocks part of the light transmitted through the printing paper P. The light restricting unit 3 has an opening W through which light received by the light receiving unit 2 passes. That is, the light restricting unit 3 is a member for preventing the transmitted light at the position on the optical axis L1 of the light source 1 and near the optical axis L1 from being received by the light receiving unit 2. The transmitted light means light emitted from the light source 1 onto the printing paper P, which is emitted from the surface on the back side of the surface on which the light is irradiated (that is, the irradiated surface). The transmitted light includes light that enters the printing paper P from the irradiation surface, diffuses in the printing paper P, and exits from the back surface.

  The CPU 4 controls the current supplied to the light source 1 and performs various calculations based on the light receiving signal output from the light receiving unit 2. Specifically, the CPU 4 receives the light received by the light receiving unit 2 without passing through the printing paper P, the amount of light emitted from the light source 1 to the printing paper P, and the light received by the light receiving unit 2 through the printing paper P. Then, the absorbance of the printing paper P is calculated using the amount of light (for example, Lambert-Beer equation). Further, the CPU 4 calculates the grammage corresponding to the calculated absorbance based on the correspondence between the absorbance and the grammage value defined in advance. The grammage is a value indicating the weight per unit area of the printing paper P. The control and calculation performed by the CPU 4 may be executed by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like.

  The constant current source 5 is a member for supplying a constant current to the light source 1, and the variable resistor 6 is a resistor for controlling the current supplied to the light source 1. The amplifying circuit 7 is a circuit for amplifying a signal obtained according to the amount of light received by the light receiving unit 2, and the A / D converter 8 converts the received light signal amplified by the amplifying circuit 7 into an A / D signal. D-converted and output to CPU4.

(Relationship between position of receiving light transmitted through printing paper P and intensity of transmitted light)
Next, the relationship between the position at which the light transmitted through the printing paper P is received and the intensity of the transmitted light will be described with reference to FIG. FIG. 2 is a diagram for explaining that the intensity of light transmitted through the printing paper P and the spread of the diffusion region B differ depending on the degree of light scattering within the printing paper P.

  As shown in FIG. 2, when light is emitted from the light source 1 toward the printing paper P, the amount of light transmitted through the printing paper P is higher as the light source 1 is closer to the optical axis L1. It becomes lower as it deviates from the axis L1. When light emitted from the light source 1 onto the printing paper P passes through the printing paper P, the light is diffused by light scattering inside the printing paper P. Therefore, the diffusion area B of the light transmitted through the printing paper P is wider than the irradiation area A of the light applied to the printing paper P (see FIG. 1).

  As shown in FIG. 2, the intensity of the transmitted light in the high-scattering printing paper P (hereinafter, referred to as high-scattering paper) is low near the center of the light irradiated on the printing paper P, and the transmitted light is low in the diffusion region B2. Is detected. On the other hand, in the case of the low-scattering printing paper P (hereinafter, referred to as low-scattering paper), transmitted light is detected in the diffusion region B1 which is high near the center of the light applied to the printing paper P and narrower than the diffusion region B2.

  The degree of light scattering inside the printing paper P (light scattering characteristics) differs depending on the quality and brand of the printing paper P. Since the difference in the light scattering characteristics affects the intensity of the light received by the light receiving unit 2 and transmitted through the printing paper P, an error occurs in the basis weight. For example, even if the printing paper P has the same basis weight, the intensity of the transmitted light in the diffusion region B1 is high in the case of the low scattering paper, and the intensity of the transmitted light in the diffusion region B2 is low in the case of the high scattering paper. . This tendency is remarkable in transmitted light on the optical axis L1 of the light source 1 and at a position close to the optical axis L1. Therefore, when the absorbance of the printing paper P is calculated based on the light receiving signal that receives the transmitted light on the optical axis L1 of the light source 1 and at a position close to the optical axis L1, the apparent absorbance of the low scattering paper is calculated to be low. There is a tendency that the apparent absorbance of the high scattering paper tends to be calculated high. As a result, a lower basis weight is calculated for low scattering paper with respect to the original basis weight, and a higher basis weight is calculated for high scattering paper.

  The applicants limit the light received by the light receiving unit 2 to transmitted light at a position away from the optical axis of the light source 1 by a predetermined distance D1, thereby reducing the influence of the scattering characteristic of the printing paper P, It has been found that the basis weight can be calculated with high accuracy (see Example 1 described later).

  Therefore, in the measuring device 10, in order to avoid receiving the transmitted light on the optical axis L1 of the light source 1 and at a position close to the optical axis L1, the light receiving unit 2 is configured such that the optical axis L1 of the light source 1 is It is arranged so that the intersection of the optical axis L2 and the printing paper P is located at a position separated by a predetermined distance D1 from the intersection. In addition, the measuring device 10 controls the light restricting unit 3 so that the light receiving unit 2 receives a part of the light transmitted through the printing paper P and a position at a predetermined distance D1 from the optical axis L1 of the light source 1. It has. Here, the predetermined distance D1 may be any distance that does not include the optical axis of the light source 1 within the light receiving angle of the light receiving unit 2, for example, (distance from the light source 1 to the printing paper P) × ｛. It is desirable that the distance be equal to or longer than tan (irradiation angle θ of light source 1)｝. Here, the irradiation angle θ means an angle between the optical axis L1 and a light beam whose light intensity is reduced to 50% of the light intensity on the optical axis L1. When the optical axis L1 of the light source 1 is inclined by an angle α (not shown) with respect to a perpendicular drawn from the light source L1 to the object, the predetermined distance D1 is (distance from the light source 1 to the printing paper P). ) × {tan (tilt α of light source) + tan (difference between irradiation angle θ of light source 1 and tilt α of light source 1)}.

  According to this configuration, it is possible to suppress occurrence of an error in the basis weight for each of the printing papers P having different degrees of light scattering. Therefore, when the measuring apparatus 10 is applied to the image forming apparatus 100 (for example, a copying machine, a printer, and a multifunction peripheral), appropriate printing conditions are controlled according to the basis weight calculated for each printing paper P. Printing can be performed.

  Further, the above configuration does not require providing a plurality of light receiving elements or providing a dedicated laser as the light source 1. Therefore, there is no problem that the cost required for manufacturing the measuring apparatus 10 and the image forming apparatus 100 increases.

(Opening W of light restricting unit 3)
Here, the opening W of the light restricting unit 3 will be described with reference to FIG. FIG. 3 is a view showing some examples of the opening W provided in the light restricting unit 3.

  The light restricting section 3 is made of a material having a light blocking property, and blocks light on the optical axis L1 of the light source 1. In addition, the light restricting unit 3 includes an opening W so that light on the periphery of the light in the diffusion region B passes. Thereby, the light received by the light receiving unit 2 can be appropriately limited.

  The opening W may be a hole provided in the light restricting portion 3 as shown in FIGS. 3A and 3B, or may be a light restricting portion 3 as shown in FIG. May be provided in the notch. Note that the opening W may be realized using a material having light transmittance, unlike the other parts of the light restricting unit 3.

(Image forming apparatus 100)
Next, the configuration of the image forming apparatus 100 will be described with reference to FIG. 4A. FIG. 4A is a block diagram illustrating a configuration example of an image forming apparatus 100 including the measuring apparatus 10. The image forming apparatus 100 includes a measuring device 10, a paper feeding device 20, a control device 30, and a printing device 40.

  The paper feeding device 20 supplies the printing paper P to the measuring device 10. The fed printing paper P is transported between the light source 1 and the light receiving unit 2.

  The control device 30 controls the operations of the measuring device 10, the paper feeding device 20, and the printing device 40 in an integrated manner. For example, the control device 30 controls printing conditions according to the basis weight calculated by the measuring device 10. Further, the control device 30 controls the printing device 40 to form an image on the printing paper P under the designated printing conditions.

(Process Flow of Image Forming Apparatus 100)
Subsequently, an operation example in the image forming apparatus 100 will be described with reference to FIG. 4B. FIG. 4B is a flowchart illustrating an example of a processing flow of the image forming apparatus 100.

  When receiving a print instruction from the user (YES in step S1), image forming apparatus 100 measures the amount of light received by light receiving unit 2 before printing paper P is supplied to measuring apparatus 10 (step S1). Step S2). After the measurement in step S2, the paper feeding device 20 conveys the printing paper P so that the printing paper P comes between the light source 1 and the light receiving unit 2, and supplies the printing paper P to the measuring device 10 (step S3). .

  Next, the measuring device 10 measures the amount of light transmitted through the printing paper P when the printing paper P is irradiated with light from the light source 1 (step S4: light irradiation step, light receiving step). At this time, the amount of transmitted light to be measured may vary depending on the state in which the printing paper P is transported to the measuring device 10. Therefore, the CPU 4 determines whether or not the variation in the amount of transmitted light to be measured falls within a range of a preset value (set value in the figure) (step S5: light irradiation step, light receiving step). Steps). When the variation in the amount of transmitted light that is measured is not within the range of the preset value (NO in step S5), the CPU 4 calculates an average value of the measured amounts of light (step S6). Steps S4 and S5 are repeated until the variation falls within a preset value range.

  If the difference between the amount of transmitted light measured in step S4 and the average value of the amount of light calculated in step S6 falls within the set range (YES in step S5), CPU 4 The absorbance of the printing paper P is calculated using the light amount measured in step S2 and the average value of the amount of transmitted light when YES is obtained in step S5 (step S7). Then, the CPU 4 calculates the basis weight of the printing paper P from the calculated absorbance (Step S8: calculation step).

  The control device 30 controls printing conditions according to the basis weight calculated by the CPU 4 of the measuring device 10 (step S9), and controls the printing device 40 to execute printing on the printing paper P under the printing conditions (step S9). Step S10).

  With this configuration, it is possible to execute printing on the printing paper P of various paper qualities and brands by controlling appropriate printing conditions.

[Embodiment 2]
Another embodiment of the present disclosure will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

  When the light receiving portion 2 having a narrow light receiving angle is used, the apparent light absorbance is calculated to be high because the amount of transmitted light to be received is small for the printing paper P having a large light scattering characteristic, and as a result, the basis weight is high. It tends to be calculated.

  To avoid this error, the direction of the optical axis L2 of the light receiving section 2 may be adjusted. The configuration of the measuring device 10a having such a configuration will be described with reference to FIG. FIG. 5 is a cross-sectional view illustrating another arrangement example of the light source 1 and the light receiving unit 2. Note that the measurement device 10a also includes a CPU 4 (calculation unit), a constant current source 5, a variable resistor 6, an amplifier circuit 7, and an A / D converter 8, similarly to the measurement device 10 illustrated in FIG.

  The measuring device 10a is different from the measuring device 10 shown in FIG. 1 in that the measuring device 10a further includes a light receiving unit optical axis control unit 21. The light receiving unit optical axis control unit 21 adjusts the direction of the optical axis L2 of the light receiving unit 2 so that the light passing through the opening W of the light limiting unit 3 is received by the light receiving unit 2, as shown in FIG. I do. The control of the direction of the optical axis L2 of the light receiving unit 2 by the light receiving unit optical axis control unit 21 can be executed by, for example, the CPU 4. As a result, as shown in FIG. 5, the position where the optical axis L1 of the light source 1 intersects the printing paper P and the normal (optical axis L2) passing through the center of the light receiving surface of the light receiving unit 2 intersect the printing paper P. And a predetermined distance D2. The predetermined distance D2 is desirably equal to or more than a distance obtained by, for example, (distance from the light source 1 to the printing paper P) × {tan (irradiation angle θ of the light source 1)}.

  By adjusting the direction of the optical axis L2 of the light receiving unit 2, it is possible to enlarge the region of light that can be received by the light receiving unit 2. Therefore, even when the light receiving unit 2 having a narrow light receiving angle is used, the basis weight can be predicted with high accuracy as in the above-described embodiment.

[Embodiment 3]
Another embodiment of the present disclosure will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

  When the light source 1 having a small irradiation angle θ is used, the light restricting unit 3 blocks the transmitted light on the optical axis L1 of the light source 1 and a position close to the optical axis L1, and the light restricting unit 3 controls the light at a position separated by a predetermined distance from the optical axis L1. It may be difficult to allow the transmitted light to pass through the opening W. As a result, the basis weight may not be calculated correctly.

  To solve this problem, the direction of the optical axis L1 of the light source 1 may be adjusted. The configuration of the measuring device 10b having such a configuration will be described with reference to FIG. FIG. 6 is a cross-sectional view illustrating another arrangement example of the light source 1 and the light receiving unit 2. Note that the measurement device 10a also includes a CPU 4 (calculation unit), a constant current source 5, a variable resistor 6, an amplifier circuit 7, and an A / D converter 8, similarly to the measurement device 10 illustrated in FIG.

  The measuring device 10b is different from the measuring device 10 shown in FIG. 1 in that the measuring device 10b further includes a light source optical axis control unit 11. The light source optical axis control unit 11 adjusts the direction of the optical axis L1 of the light source 1, as shown in FIG. The light source optical axis control unit 11 controls, for example, a direction in which the optical axis L1 of the light source 1 irradiates the printing paper P with light vertically. As a result, as shown in FIG. 6, the position where the optical axis L1 of the light source 1 intersects the printing paper P and the normal (optical axis L2) passing through the center of the light receiving surface of the light receiving unit 2 intersect the printing paper P. The position is apart from the position by a predetermined distance D3. The predetermined distance D3 is obtained, for example, by (distance from the light source 1 to the printing paper P) × {tan (tilt α of the light source) + tan (difference between the irradiation angle θ of the light source 1 and the tilt α of the light source 1)}. It is desirable that the distance be longer than the distance. The control of the direction of the optical axis L1 of the light source 1 by the light source optical axis control unit 11 can be executed by, for example, the CPU 4.

  By controlling the optical axis L1 of the light source 1 to a direction different from the direction in which light is emitted perpendicularly to the printing paper P, the irradiation area A of the light applied to the printing paper P can be enlarged. Thereby, it becomes easy to transmit the transmitted light at a position separated by a predetermined distance D3 from the optical axis L1 through the opening W and make the light receiving unit 2 receive the transmitted light.

[Embodiment 4]
Another embodiment of the present disclosure will be described below. For convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

  When the light source 1 having a narrow irradiation angle θ and the light receiving section 2 having a narrow light receiving angle are used together, it becomes difficult for the light receiving section 2 to receive the transmitted light at a position away from the optical axis L1 of the light source 1 by a predetermined distance. On the other hand, in the case of high scattering paper, there may be a problem that the amount of light received by the light receiving unit 2 is low. As a result, an error may occur in the grammage.

  In order to avoid this error, the direction of the optical axis L1 of the light source 1 and the direction of the optical axis L2 of the light receiving section 2 may be adjusted. The configuration of the measuring apparatus 10c having such a configuration will be described with reference to FIG. FIG. 7 is a cross-sectional view illustrating another arrangement example of the light source 1 and the light receiving unit 2. Note that the measurement device 10a also includes a CPU 4 (calculation unit), a constant current source 5, a variable resistor 6, an amplifier circuit 7, and an A / D converter 8, similarly to the measurement device 10 illustrated in FIG.

  The measuring device 10c is different from the measuring device 10 shown in FIG. 1 in that both the light source optical axis control unit 11 and the light receiving unit optical axis control unit 21 are further provided. The light source optical axis control unit 11 and the light receiving unit optical axis control unit 21 determine the direction of the optical axis L2 of the light source 1 and the light receiving unit 2, respectively, and the light passing through the opening W of the light limiting unit 3 is received by the light receiving unit 2. To adjust. As a result, as shown in FIG. 7, the position where the optical axis L1 of the light source 1 intersects the printing paper P and the normal (optical axis L2) passing through the center of the light receiving surface of the light receiving unit 2 intersect the printing paper P. The position is apart from the position by a predetermined distance D4. The predetermined distance D4 is obtained by, for example, (distance from the light source 1 to the printing paper P) × {tan (inclination α of the light source) + tan (difference between the irradiation angle θ of the light source 1 and the inclination α of the light source 1)}. It is desirable that the distance be longer than the distance. The control of the direction of the optical axis L2 of the light receiving unit 2 by the light receiving unit optical axis control unit 21 can be executed by, for example, the CPU 4.

  By providing both the light source optical axis control unit 11 and the light receiving unit optical axis control unit 21, both the expansion of the irradiation area A and the expansion of the area of light that can be received by the light receiving unit 2 can be realized. Therefore, even when the light source 1 having a narrow irradiation angle θ and the light receiving unit 2 having a narrow light receiving angle are used together, it is possible to accurately estimate the basis weight.

  The present disclosure is not limited to the above embodiments, and various modifications are possible within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments. Is also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

  One embodiment of the present disclosure will be described below.

  FIG. 8 is a diagram illustrating results that demonstrate the effectiveness of the measurement method according to an embodiment of the present disclosure. In the following, a case where the weighing of the printing paper P is measured will be described as an example, and the results will be described.

The printing paper P was irradiated with light, the absorbance of the printing paper P was calculated, and the basis weight was measured from the absorbance. As samples of the printing paper P, four types of printing papers a, b, c, and d which are commercially available were used. For the printing papers a, b, c, and d, the previously measured basis weight values were 67.55 g / m ² , 68.85 g / m ² , 75.36 g / m ² , and 90.25 g / m ² , respectively. there were.

  As the light source 1, a light emitting LED (SMT940D manufactured by epitex) emitting light having a wavelength of 940 nm was used, and as the light receiving unit 2, a silicon PIN photodiode (manufactured by Vishay) was used.

  The irradiation angle θ of the light source used in this embodiment is 61 °, the distance from the light source to the object is 2 mm, and the inclination of the light source is 0 °, so that the predetermined distance (see the predetermined distance D1 in FIG. 1) Is 2 mm × tan (61 °) = 3.61 mm or more from the above formula.

  As the light restricting portion 3, an opening W having a circular hole with a diameter of 3 mm was used.

  The light was irradiated such that the optical axis L1 of the light source 1 was substantially perpendicular to the printing paper P. The light receiving section 2 is installed such that its optical axis L2 is substantially perpendicular to the printing paper P. Then, the position of the light receiving unit 2 was changed with respect to the optical axis L1 of the light source 1, and the absorbance of the printing papers a, b, c, and d was measured. FIG. 8A is a graph in which the absorbances of the printing papers a, b, c, and d calculated at each measurement position are plotted.

If the scattering properties of the printing papers a, b, c, and d are the same, the basis weight and the absorbance have a positive correlation. The higher the absorbance, the greater the basis weight. However, in practice, since the scattering properties of the printing papers a, b, c, and d are different from each other, the basis weight and the absorbance do not show a positive correlation. For example, according to (a) in FIG. 8, the measured basis weight values found the following printing paper a of 67.55g / ^{m 2,} high absorbance than the printing paper c of the measured basis weight values 75.36g / ^{m 2} Is shown.

FIG. 8B is a graph in which the relationship between the absorbance calculated from the amount of light measured on the optical axis L1 of the light source 1 and the measured basis weight value is plotted. Performs straight-line approximation for each point plotted, The correlation coefficient R ^2, became 0.4654. No high correlation was observed between the absorbance measured on the optical axis L1 of the light source 1 and the measured basis weight value.

On the other hand, FIG. 8C shows the relationship between the absorbance calculated from the amount of light measured at a position separated from the optical axis L1 of the light source 1 by a predetermined distance (4 mm in this embodiment) and the measured basis weight value. It is a graph plotted. Performs straight-line approximation for each point plotted, The correlation coefficient R ^2, became 0.9972. A high correlation was observed between the absorbance measured on the optical axis L1 of the light source 1 and the measured basis weight value. When other positions were confirmed, similarly, a high correlation was recognized at a position equal to or longer than the distance (3.61 mm) obtained from the above formula. If the distance is too large (away from the optical axis L1), the light received by the light receiving unit 2 will decrease. That is, the upper limit of the distance for measuring the grammage or the like with high accuracy can be appropriately designed in consideration of the light receiving sensitivity of the light receiving unit 2.

  As described above, by using the light received by the light receiving unit 2 with the absorbance calculated using the transmitted light at a position separated from the optical axis of the light source 1 by a predetermined distance, the printing paper P has high scattering characteristics. Regardless of the low scattering characteristics, the basis weight could be calculated with high accuracy.

Reference Signs List 1 light source 2 light receiving unit 3 light limiting unit 4 CPU (calculation unit)
10, 10a, 10b, 10c Measuring device 11 Light source optical axis control unit 21 Light receiving unit optical axis control unit 100 Image forming device L1 Optical axis of light source L2 Optical axis B, B1, B2 of light receiving unit Diffusion area W Opening θ Light source Illumination angle

Claims (11)

A light source that emits light to illuminate the object,
A light receiving unit that receives transmitted light from the object,
A light limiting unit that limits a part of the transmitted light toward the light receiving unit,
A measuring device comprising:
The position at which the optical axis of the light source intersects with the object and the position at which the normal passing through the center of the light receiving surface of the light receiving unit intersects with the object are separated by a predetermined distance,
A measuring apparatus, further comprising a calculating unit that calculates a predetermined characteristic of the object based on a light amount of light emitted from the light source to the object and a light amount of light received by the light receiving unit.   The measuring device according to claim 1, wherein the light restricting unit blocks light on an optical axis of the light source.   The measuring device according to claim 1, wherein the light restricting unit includes an opening through which light at a position separated by a predetermined distance from an optical axis of the light source passes.   The measuring device according to claim 3, wherein the opening is a notch or a hole.   The measuring device according to claim 1, wherein the predetermined distance is a distance that does not include an optical axis of the light source within a light receiving angle of the light receiving unit.   The said predetermined distance is more than the value calculated | required by the product of the distance from the said light source to the said object, and the tangent of the irradiation angle of the said light source, The Claim 1 characterized by the above-mentioned. Measuring device.   The measuring apparatus according to claim 1, further comprising a light receiving unit optical axis control unit configured to control a direction of an optical axis of the light receiving unit.   The measuring apparatus according to claim 1, further comprising a light source optical axis control unit configured to control a direction of an optical axis of the light source. The measuring device according to claim 1, wherein at least one of a basis weight, a scattering coefficient, and an anisotropic scattering parameter of the object is calculated.   An image forming apparatus, comprising: the measuring device according to claim 1. A light irradiation step of irradiating the object with light from a light source;
A light receiving step of receiving, by a light receiving unit, light that has passed through a light limiting unit that limits a part of transmitted light from the object,
A measurement method comprising:
The position at which the optical axis of the light source intersects with the object and the position at which the normal passing through the center of the light receiving surface of the light receiving unit intersects with the object are separated by a predetermined distance,
A measuring step of calculating a predetermined characteristic of the object based on a light amount of light emitted from the light source to the object and a light amount of light received in the light receiving step.

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