JP2006053107A - Optical measuring instrument and its assembling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical measuring instrument suppressed in measuring error caused by minute fluctuations in the distance between measuring targets, and provide its assembling method. <P>SOLUTION: In the optical measuring instrument equipped with a light source for emitting a light beam to the measuring target and a light detection part for detecting the measuring light emitted from the light source to be reflected by the measuring target to output the detection light signal corresponding to the measuring light, the light source has characteristics, wherein an intensity constant point almost constant in the illumination intensity of the light beam within a spot formed by irradiating the measuring target with the light beam even if the distance up to the measuring target from the light source fluctuate within a predetermined range, at a place off the optical axis of the light source and the light detection part has the optical axis passing through the intensity constant point. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a light source that emits a light beam to a measurement object, and a light receiving unit that receives the measurement light emitted from the light source and reflected by the measurement object, and outputs a light reception signal corresponding to the measurement light. The present invention relates to an optical measuring device provided and an assembling method of the optical measuring device.

  2. Description of the Related Art Conventionally, there has been known an image forming apparatus such as a printer that forms a toner image on an image carrier such as a photoconductor and transfers and fixes the toner image on a recording medium such as paper. Yes.

  In such an image forming apparatus, whether or not the toner density of the toner image transferred onto the recording medium is correct is determined by verifying the density of a dummy toner image called a patch formed during image formation. ing. This verification is performed by determining the output level from the light receiving element that receives the reflected light that is irradiated from the light emitting element toward the patch and reflected by the surface of the patch (see Patent Document 1).

  FIG. 1 is a diagram illustrating an example of a toner concentration measuring apparatus including the above-described light emitting element and light receiving element.

  In FIG. 1, a toner concentration measuring apparatus 100 including a light emitting diode 101 as a light emitting element and a photodiode 102 as a light receiving element has a predetermined distance from a patch 110 to be measured (hereinafter, this distance is referred to as a measurement distance). The state of being deployed is shown. 1 includes a light-emitting side stop 101a, a light-receiving lens 102a, and a light-receiving side stop 102b. In FIG. 1, a patch 110 is provided on the intermediate transfer belt 120. It shows how it is formed.

  Further, FIG. 1 shows a state in which the light emitting optical axis S of the light emitting diode 101 and the light receiving optical axis R of the photodiode 102 intersect at a position X on the surface of the patch 110.

  FIG. 2 is a graph showing the relationship between the illumination intensity and the position on the patch surface in the toner concentration measuring apparatus shown in FIG.

  In FIG. 2, the toner concentration measuring apparatus 100 shown in FIG. 1 is designed so that the illumination intensity reaches a peak at the intersection X between the optical axis S of the light emitting diode 101 and the optical axis R of the photodiode 102. It is shown that there is.

  FIG. 3 is a graph showing the relationship between the received light intensity and the measurement distance.

  FIG. 3 shows the light receiving characteristics of a photodiode in which the received light intensity increases as the measurement distance approaches the specification, and the received light intensity decreases as the distance increases.

  FIG. 4 is a graph showing the sensor output for each measurement distance from the toner concentration measuring apparatus shown in FIG.

The sensor output shown in FIG. 4 includes the illumination intensity characteristic shown in FIG. 2, the light receiving characteristic shown in FIG. 3, the change in the illumination intensity itself accompanying the change in the measurement distance, and the light emission optical axis S and the patch that is not measured. This is a reflection of the change in illumination intensity on the light receiving optical axis due to the movement of 110 intersections (not X when shifted).
JP-A-3-045972

  By the way, even if the toner density measuring device 100 is attached to a printer, a copying machine or the like with an interval as specified between the intermediate transfer belt and the intermediate transfer belt, there is a considerable installation error, and the intermediate transfer in which a patch is formed. There is no guarantee that undulation will not occur in the belt.

  In such a case, since the measurement distance is deviated from the specification, the sensor output is greatly different as shown in FIG. 4, which causes a problem that accurate density detection cannot be performed.

  Note that what has been described above is not a problem that occurs only in toner image density detection, but a transfer position for optically detecting whether or not the toner image is accurately transferred to a target position on the recording medium. This is also a problem that occurs in the detection device and the like.

  In view of the circumstances described above, an object of the present invention is to provide an optical measurement device in which measurement errors due to slight fluctuations in the distance to the measurement object are suppressed, and a method for assembling such an optical measurement device.

In order to achieve the above object, an optical measurement apparatus of the present invention comprises:
Optical measurement including a light source that emits a light beam to a measurement object, and a light receiving unit that receives the measurement light emitted from the light source and reflected by the measurement object, and outputs a light reception signal corresponding to the measurement light In the device
The light source is located in a spot where the measurement object is irradiated with the light beam even if the distance from the light source to the measurement object fluctuates within a predetermined range at a position off the optical axis of the light source. It has the characteristic that there is a constant intensity point where the illumination intensity of this light beam is substantially constant,
The light receiving unit has an optical axis passing through the constant intensity point.

  In the optical measurement device of the present invention, the optical axis of the light receiving unit substantially determines the characteristics of the measurement light, and the illumination intensity of the light beam is substantially constant even if the distance to the measurement object changes within a predetermined range. It is designed to pass through a fixed point. Therefore, according to the optical measurement device of the present invention, even if the distance to the measurement object changes within a predetermined range, it is possible to suppress the change in the output of the received light signal, thereby reducing the distance to the measurement object. Measurement errors due to minute fluctuations can be suppressed.

In order to achieve the above object, an assembling method of the optical measuring device of the present invention comprises:
A light source that emits a light beam onto the surface to be measured, and a light receiving unit that receives the measurement light emitted from the light source and reflected on the surface to be measured, and outputs a light reception signal according to the measurement light In the assembly method of the optical measuring device,
A first step of disposing each of the light source and the light receiving unit such that the optical axis of the light source and the optical axis of the light receiving unit pass on the surface to be measured;
Even if the distance between the light source and the surface to be measured fluctuates within a predetermined range, an intensity constant point where the illumination intensity of the light beam is substantially constant in a spot formed by the light beam being irradiated on the surface to be measured. And a second step for matching the passing point of the optical axis of the light receiving unit on the surface to be measured.

  Here, the second step may be a step of matching the constant intensity point and the passing point by changing the arrangement position of the light source arranged in the first step.

  Alternatively, the second step may be a step of matching the fixed intensity point and the passing point by changing the shape of the spot.

  By changing the shape of the spot in this way, it is possible to change the characteristics of the illumination intensity, thereby making it possible to match the constant intensity point and the passing point without changing the relative positions of the light source and the light receiving unit. It is convenient.

  According to the optical measuring device of the present invention assembled by the assembling method of the optical measuring device of the present invention, it is possible to suppress a measurement error due to a slight variation in the distance to the measurement object.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 5 is a graph showing the relationship between the illumination intensity and the position on the patch surface for each measurement distance, including FIG.

  FIG. 5 shows a position Y on the patch surface where the illumination intensity is substantially constant even when the measurement distance of the light emitting diode changes.

  Conventionally, the optical axis R of the photodiode is aligned with the point where the optical axis S of the light-emitting diode intersects the surface to be measured. In contrast, the optical measurement apparatus of the present invention provides illumination intensity even when the measurement distance changes. By aligning the optical axis of the light receiving element at a substantially constant position on the surface to be measured, a stable sensor output can be realized against slight fluctuations in the distance between the surface to be measured and the optical measuring device.

  FIG. 6 is a diagram showing a first embodiment of the optical measurement device of the present invention assembled by an embodiment of the assembly method of the optical measurement device of the present invention.

  A toner concentration measuring apparatus 10 according to the present embodiment illustrated in FIG. 6 includes a light emitting unit 11 provided with a light emitting diode 111 that is a light emitting element, and a light receiving unit 12 provided with a photodiode 121 that is a light receiving element. It is installed inside a printer or copier to measure toner density and position. The toner concentration measuring device 10 fixes the light emitting unit 11 and the light receiving unit 12 in the direction related to the distance between the patch surface, but the light emitting unit 11 and the light receiving unit 12 related to the position on the patch surface. The mechanism which can change the space | interval between is provided.

  FIG. 6 shows a state in which a gap is secured between the light receiving unit 12 and the light emitting unit 11. By securing this gap, the optical axis of the light emitting diode 111 is changed from the optical axis S shown in FIG. 6. A state of changing to the optical axis S ′ is shown. In the toner concentration measuring apparatus 10 of the present embodiment, by adjusting the distance between the light receiving unit 12 and the light emitting unit 11, the photodiode 121 is positioned at a position Y on the patch surface where the illumination intensity is substantially constant even if the measurement distance changes. The optical axis is aligned. The light emitting diode 111 used in the toner concentration measuring apparatus 10 has a constant intensity point where the illumination intensity is constant even when the distance to the patch surface fluctuates within a predetermined range at a position off the optical axis. It has existing characteristics.

  Here, the assembly adjustment before factory shipment of the toner concentration measuring apparatus 10 in which the distance to the object to be measured is set will be described.

  FIG. 7 is a diagram showing a flow of assembly adjustment of the toner concentration measuring apparatus.

  In step S1 shown in FIG. 7, the toner density measuring device 10 to be adjusted is attached to a jig (not shown) in which a reference plate having a predetermined density or reflectance is already installed instead of the patch. . With this jig, it is possible to change the measurement distance between the reference plate and the toner concentration measuring device 10 and the interval between the light emitting unit 11 and the light receiving unit 12, and the photo of the toner concentration measuring device 10 can be changed. The sensor output from the diode 121 can be recorded. In step S <b> 2, the light emitting unit 11 and the light receiving unit 12 are arranged with a provisional interval (here, an interval of 0 mm) and a distance set as a specification secured between the reference plate. In step S3, a measurement distance at which the output is maximized is obtained while changing the measurement distance between the reference plate and the toner density measuring device 10. In step S4, the movement / adjustment amount of the light emitting unit 11 and the light receiving unit 12 is obtained based on the relationship shown in Table 1.

  The relationship shown in Table 1 is the relationship between the measurement distance and the movement / adjustment amount between light emission and emission in order to make the optical axis of the photodiode coincide with a substantially constant intensity constant point of illumination intensity. It was discovered.

  In step S5, the light emitting unit 11 and the light receiving unit 12 are temporarily fixed at a position corresponding to the movement / adjustment amount obtained in step S4. In step S6, the variation amount of the sensor output from the photodiode 121 is measured while changing the measurement distance between the reference plate and the toner density measuring device 10 around the specification setting distance. In step 7, the fluctuation amount of the sensor output is confirmed. When the fluctuation amount is not within the predetermined range, re-movement / re-adjustment is performed, and the movement / adjustment amount is finely adjusted.

  FIG. 8 is a diagram showing sensor output when the distance between the reference plate and the toner density measuring device to be adjusted is changed around the specification setting distance.

  FIG. 8 shows how the sensor output fluctuation is smaller than the fluctuation in FIG. 4 when ± 0.5 mm is changed around the specification setting distance.

  Finally, the light emitting unit 11 and the light receiving unit 12 are permanently fixed at a light receiving / emitting interval where the optical axis of the photodiode coincides with a constant intensity point (step 8), and the assembly adjustment of the toner concentration measuring device 10 is finished. The toner concentration measuring device 10 having the light emitting unit 11 and the light receiving unit 12 fixed thereto is handed over to an assembly factory such as a printer or a copying machine, and is incorporated into the printer or the copying machine so as to be arranged at a specification setting distance. By doing so, it is possible to measure the concentration stably even with a slight change in the distance to the object to be measured. Therefore, according to the toner concentration measuring apparatus 10 of the present embodiment, it is possible to suppress a measurement error due to a slight variation in the distance to the measurement target.

  FIG. 9 is a diagram showing a second embodiment of the optical measurement apparatus of the present invention.

  The difference between the first embodiment shown in FIG. 6 and the second embodiment shown in FIG. 9 is that in the second embodiment, the light emitting unit and the light receiving unit are integrated, and illumination is performed even if the measurement distance changes. Aligning the optical axis of the photodiode to a position on the patch surface where the intensity is substantially constant, rather than moving the light emitting portion relative to the light receiving portion, reduces the spot range formed on the patch surface by the irradiation light from the light emitting diode. It is only a point to do.

  In the toner concentration measuring apparatus 20 of the present embodiment shown in FIG. 9, a light shielding member 213 for adjusting the spot range of the irradiation light from the light emitting diode 211 is provided, and this light shielding member 213 is in the direction of arrow B. By rotating, the spot range is reduced.

  In the toner concentration measuring device 20 of the present embodiment, the same effect as the toner concentration measuring device 10 of the first embodiment is obtained by rotating the light shielding member 213 to change the spot range.

  In FIG. 9, the spot length when the light shielding member 213 is rotated by a predetermined angle in the direction of the arrow B is indicated by a dimension b, and the light shielding member 213 is rotated in the direction of the arrow A to be retracted. The spot length is indicated by dimension a.

  Further, FIG. 9 shows a state in which the light axis is changed from the optical axis S to the optical axis S ′ while the light emitting diode 211 is fixed by reducing the spot range by rotating the light shielding member 213. Yes.

  Regarding the assembly adjustment of the toner concentration measuring apparatus 20 of the present embodiment, the rotation angle of the light shielding member 213 is determined instead of the interval between the light receiving unit 12 and the light emitting unit 11 in the first embodiment. However, since the difference is only the difference, the toner concentration measuring apparatus 20 of the present embodiment can also suppress measurement errors due to slight fluctuations in the distance to the measurement target.

  In the embodiment described above, the case where a mechanism for changing the interval between the light emitting part and the light receiving part is provided, and the case where a light shielding member for changing the spot range due to the irradiation light from the light emitting diode is provided as an example. The present invention is not limited as long as the optical axis of the light receiving element can be moved to a position on the surface to be measured where the illumination intensity is substantially constant even if the measurement distance is changed, and the mounting angle of the light emitting element can be changed and adjusted. You may comprise like this. Further, the light emitting element may be swingable.

It is a figure which shows an example of the toner density | concentration measuring apparatus comprised by the above-mentioned light emitting element and a light receiving element. It is a graph which shows the relationship between illumination intensity and the position on the patch surface. It is a graph which shows the relationship between received light intensity and measurement distance. FIG. 2 is a graph showing sensor output for each measurement distance from the toner concentration measuring apparatus shown in FIG. 1. It is a graph figure for every measurement distance of the relationship between illumination intensity and the position on a patch surface including FIG. It is a figure which shows 1st Embodiment of the optical measuring device of this invention. FIG. 5 is a diagram illustrating a flow of adjustment of a toner concentration measuring device. It is a figure which shows the output at the time of changing the measurement distance between the reference | standard board and the toner density measuring apparatus of adjustment object centering on the distance of specification. It is a figure which shows 2nd Embodiment of the optical measuring device of this invention.

Explanation of symbols

10, 20 Toner density measuring device 11 Light emitting unit 110 Patch 111 Light emitting diode 12 Light receiving unit 120 Intermediate transfer belt 121 Photodiode 213 Light shielding member

Claims (4)

Optical measurement comprising a light source that emits a light beam to a measurement object, and a light receiving unit that receives the measurement light emitted from the light source and reflected by the measurement object, and outputs a light reception signal corresponding to the measurement light In the device
The light source is located in a spot formed by irradiating the measurement object with the light beam even if the distance from the light source to the measurement object fluctuates within a predetermined range at a position off the optical axis of the light source. It has a characteristic that there is a constant intensity point where the illumination intensity of the light beam is substantially constant,
The optical measuring device, wherein the light receiving unit has an optical axis passing through the constant intensity point. A light source that emits a light beam on the surface to be measured, and a light receiving unit that receives the measurement light emitted from the light source and reflected on the surface to be measured, and outputs a light reception signal corresponding to the measurement light In the assembly method of the optical measuring device,
A first step of disposing each of the light source and the light receiving unit such that each of the optical axis of the light source and the optical axis of the light receiving unit passes on the surface to be measured;
Even if the distance between the light source and the surface to be measured fluctuates within a predetermined range, an intensity constant point at which the illumination intensity of the light beam is substantially constant in a spot formed by irradiating the light beam on the surface to be measured And a second step of matching the passing point of the optical axis of the light receiving unit on the surface to be measured.   3. The optical measurement according to claim 2, wherein the second step is a step of making the constant intensity point and the passing point coincide with each other by changing an arrangement position of the light source arranged in the first step. Device assembly method.   3. The method of assembling an optical measurement apparatus according to claim 2, wherein the second step is a step of matching the constant intensity point and the passing point by changing the shape of the spot.

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