JP2011064822A - Reflection-type optical sensor, reflection-type optical sensor array and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a reflection-type optical sensor which detects at least one of toner pattern position and toner density. <P>SOLUTION: The reflection-type optical sensor has: an integral type light emitting/receiving element in which a semiconductor light emitting element Ei and a photodiode Di are made close to each other and arranged integrally so that the light emitting axis of the semiconductor light emitting element and the light receiving axis of the photodiode are in parallel and have an interval L; and an illuminating light condensing lens LEi which converges a light flux emitted from the semiconductor light emitting element onto the surface of a carrying medium 2040. The illuminating light condensing lens shifts the optical axis to the photodiode in parallel with the light emitting axis. The positional relations among the semiconductor light emitting element, the photodiode, and the illuminating light condensing lens are adjusted so that the light beam emitted from the semiconductor light emitting element onto the light emitting axis is refracted by the illuminating light condensing lens, enters obliquely the surface of the carrying medium orthogonal to the light emitting axis with an angle of incidence &Theta;, is regularly reflected by the surface of the carrying medium, and enters the center of the light receiving part of the photodiode, wherein the interval L is smaller than about 1 mm, and the angle of incidence &Theta; is smaller than 10 degrees. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a reflective optical sensor, a reflective optical sensor array, and an image forming apparatus.

  2. Description of the Related Art Image forming apparatuses that form toner images are widely implemented as analog or digital “monochrome or color copiers”, printers, plotters, facsimile machines, and recently multifunction printers (MFPs).

In order to obtain a good toner image with such an image forming apparatus, the amount of toner used for developing the electrostatic latent image must be appropriate.
Various development methods are known, such as a method using a “two-component developer containing toner and carrier” and a mono-toner development method using a “developer composed only of toner”. In these various development methods, the amount of toner supplied to the development unit where the electrostatic latent image is developed is also called “toner density”.

If the toner density is too low, a sufficient amount of toner is not supplied to the electrostatic latent image, and the image (output image) output from the image forming apparatus becomes an “insufficient image”. On the other hand, if the toner density is too high, the density distribution in the output image is biased toward the “high density side”, resulting in an image that is difficult to see.
Therefore, in order to obtain a good output image, it is necessary to control the toner density within an appropriate range, and for this reason, “detection of toner density” is necessary.

  Further, in the case of creating a color image, “color shift” occurs in the formed color image unless the toner images of different colors are properly superimposed, thereby degrading the image quality. For this reason, it is necessary to optimize the position of the toner image.

  For “detection of toner density” and “optimization of toner image position”, a “toner pattern” for toner density detection is formed on the surface of the photoreceptor or intermediate transfer belt, and the surface is irradiated with detection light and reflected. There are widely known methods for receiving light and detecting the toner density and the position of the toner pattern in the toner pattern based on the change in reflected light depending on the presence or absence of the toner pattern (Patent Documents 1 to 6, etc.).

  An object of the present invention is to realize a novel reflective optical sensor, a reflective optical sensor array, and an image forming apparatus using the same, which can detect the toner density and / or the position of the toner pattern using the toner pattern. To do.

  The “reflective optical sensor” of the present invention is a reflective optical sensor that detects at least one of a position and a toner density of a toner pattern having a fixed shape formed on the surface of a carrier medium carrying a toner pattern.

  The “carrying medium” is a medium in which a toner pattern is formed and carried, and is displaced to the detection unit by the reflection type optical sensor. Specifically, the photoconductive or dielectric “electrostatic” on which the toner image is formed is formed. The latent image forming medium "or an intermediate transfer medium for transferring a toner image obtained by developing the electrostatic latent image formed on the electrostatic latent image forming medium to a sheet-like image bearing medium.

The toner pattern formed on the carrier medium has a “fixed form”. The form is a shape or “shape and form”.
Regarding the shape, the “fixed shape” is a “fixed shape”, that is, a predetermined shape, but the fixed shape is not limited to one type.
“Form” is a forming condition other than the shape of the toner pattern, and is, for example, the density (preset density) of the toner pattern.

  The reflective optical sensor according to claim 1 includes an integrated light emitting / receiving element and a condenser lens for illumination.

  The integrated light-emitting / receiving element has one semiconductor light-emitting element and one photodiode.

  The “semiconductor light emitting device” is an LED (light emitting diode) or LD (semiconductor laser). The LD can be a so-called surface emitting semiconductor laser (VCSEL) as well as a so-called edge emitting type.

  In this specification, “photodiode” is a generic term for ordinary photodiodes and phototransistors.

The semiconductor light emitting element and the photodiode are integrated with each other in the following positional relationship.
That is, the “light emitting axis” of the semiconductor light emitting element and the “light receiving axis” of the photodiode are parallel to each other, and the light emitting axis and the light receiving axis are arranged close to each other.

The “light emitting axis” of the semiconductor light emitting device is an axis that is orthogonal to the light emitting surface of the semiconductor light emitting device and matches the “maximum light amount beam” emitted from the light emitting surface.
The “light receiving axis” of the photodiode is an axis that passes through the center of the light receiving surface of the photodiode and is orthogonal to the light receiving surface.
It goes without saying that both the light emitting axis and the light receiving axis are “virtual axes”.

  As described above, the semiconductor light emitting element and the photodiode are arranged so that the light emitting axis and the light receiving axis are parallel to each other, and are integrated so that the distance between the light emitting axis and the light receiving axis is L.

The semiconductor light emitting element and the photodiode can be fixedly provided on the same surface of the same holding substrate so that the light emitting axis and the light receiving axis are parallel to each other at an interval L.
The surface portion of the holding substrate on which the semiconductor light emitting element is provided and the surface portion on which the photodiode is provided may have a slight level difference.

  The “lighting condensing lens” is an optical element that has a converging effect on a light beam emitted from a semiconductor light emitting element and applied to the surface of a carrier medium on which a toner pattern is formed.

  “Illuminating condensing lens” is a micro lens like a micro lens in terms of size, and its form has a refracting curved surface like a normal convex lens (biconvex lens, plano-convex lens, convex meniscus lens). Needless to say, a Fresnel lens or a “refractive index distribution type lens having positive refractive power” may be used.

The illumination condenser lens is provided with its optical axis “parallel to the light emitting axis of the semiconductor light emitting element” and shifted to the photodiode side by a shift amount: Δ.
As described above, since the optical axis of the condenser lens for illumination is shifted to the photodiode side, the “highest intensity light beam” radiated in conformity with the emission axis of the semiconductor light emitting element is the condenser lens for illumination. In parallel with the optical axis of the light, the light is incident from the optical axis and is refracted in the optical axis direction of the illumination condenser lens, that is, toward the photodiode side.

  As described above, the light beam emitted from the semiconductor light emitting element onto the light emitting axis is refracted by the illumination condenser lens and obliquely enters the surface of the carrier medium perpendicular to the light emitting axis with an incident angle: Θ.

  Positions of the semiconductor light emitting element, the photodiode, and the illumination condenser lens so that the light is regularly reflected by the surface of the carrier medium and enters the center of the light receiving part of the photodiode (intersection of the light receiving axis and the light receiving part). The relationship is adjusted.

  This positional relationship is set so that the incident angle: Θ is 10 degrees or less.

  The distance between the light-emitting part and the light-receiving part, that is, the distance between the light-emitting axis and the light-receiving axis is preferably smaller than about 1 mm when this is L.

Of course, this positional relationship is set with respect to the “reference state”.
The “reference state” is a case where the positional relationship between the semiconductor light emitting element, the photodiode, the illumination condensing lens, and the surface of the carrier medium matches the designed positional relationship.

  The luminous flux emitted from the semiconductor light emitting element is generally a “divergent luminous flux”, and the condenser lens for illumination exerts a converging action on the divergent luminous flux by its “positive refractive power”. Due to this convergence effect, the divergence of the divergent light beam is weakened. However, the convergence effect can be such that “the light beam after passing through the illumination condenser lens becomes a weak divergent light beam”. An operation such as “the light beam after transmission becomes a parallel light beam” may be used, and further, an operation such that “the light beam after transmission becomes a convergent light beam” may be used.

  The reflection type optical sensor according to claim 1 has a light receiving condensing lens for condensing light reflected from the carrier medium toward the photodiode, and the optical axis of the light receiving condensing lens is for illumination. It is possible to adopt a configuration in which it is parallel to the optical axis of the condenser lens and shifted toward the illumination condenser lens side.

  The light beam that is concentrically accompanied by the light receiving condensing lens is incident on the center of the light receiving portion of the photodiode in the reference state.

The reflection type optical sensor according to claim 2 can be “the illumination condensing lens and the light receiving condensing lens have an integral structure” (claim 3).
The “integrated structure of the condenser lens for illumination and the condenser lens for light reception” may be a form in which the condenser lens for illumination and the condenser lens for light reception are formed as microlenses on the “same lens material substrate”, for example. In addition, the illumination condensing lens and the light receiving condensing lens manufactured separately may be connected and integrated with each other by an appropriate connector.

  The reflection type optical sensor according to any one of claims 1 to 3, wherein a light beam emitted from the semiconductor light emitting element on the light emitting axis and refracted by the illumination condenser lens is incident obliquely on the surface of the carrier medium. : Θ is preferably “set smaller than 5 degrees” (claim 4).

  The reflection-type optical sensor array of the present invention includes the reflection-type optical sensor according to any one of claims 1 to 4 as one unit, and two or more units of the reflection-type optical sensor, the light-emitting axis of the semiconductor light-emitting element, An array is arranged in a direction perpendicular to the light receiving axis of the photodiode and in a straight line passing between the light emitting axis and the light receiving axis at a pitch smaller than the size of the toner pattern in this direction, and at least the semiconductor light emitting element and the photodiode are arranged. As a whole, the semiconductor light emitting elements can be blinked independently for each reflective optical sensor unit.

  “Integrating a semiconductor light emitting element and a photodiode as a whole” means “integrating two or more semiconductor light emitting elements and two or more photodiodes arranged in an array”.

  The reflective optical sensor array according to claim 5 can be integrated with the condenser lens for illumination in the reflective optical sensor of two or more units arranged in an array (claim 6).

  6. The reflective optical sensor according to claim 6, wherein the reflective optical sensor arranged in an array has a light receiving condensing lens, and the light receiving condensing lens arranged in an array is integrated with an illumination condensing lens. (Claim 7).

  The “reflective optical sensor array” according to any one of claims 5 to 7 is such that a direction in which a plurality of units of the reflective optical sensor are arrayed is a moving direction of a toner pattern formed on the surface of the carrier medium. Are arranged to cross each other.

  An image forming apparatus according to an eighth aspect of the present invention is an “image forming apparatus that forms an image with toner”, and includes a toner image forming unit and a reflective optical sensor.

  The “toner image forming means” is a means for forming a toner pattern and “toner image for image formation” on a carrier medium (electrostatic latent image formation medium) carrying a toner pattern. In the case of a photoconductor, means for uniformly charging the surface of the photoconductor, means for forming an electrostatic latent image on the uniformly charged surface of the photoconductor by exposure, and forming the electrostatic latent image on a toner pattern or toner Developing means for developing the image.

  When the carrier medium is an “intermediate transfer belt”, together with the above units, a transfer unit that transfers the toner image formed on the photoreceptor onto the intermediate transfer belt constitutes a toner image forming unit.

  The “reflective optical sensor” is any one of claims 1 to 4 and detects “at least one of position and toner density” of a toner pattern formed on a carrier medium.

The image forming apparatus according to claim 9 is an “image forming apparatus that forms an image with toner”, and includes a toner image forming unit and a reflective optical sensor array.
The carrier medium and the toner image forming means are the same as those in the eighth aspect.
The “reflective optical sensor array” is any one of claims 5 to 7 and detects “at least one of position and toner density” of a toner pattern formed on a carrier medium.

  The image forming apparatus according to claim 8 or 9 is capable of “the image to be formed is a multicolor image or a color image with a plurality of kinds of toners having different colors” (claim 10).

  As described above, according to the present invention, a novel reflective optical sensor, reflective optical sensor array, and image forming apparatus can be realized. As will be described later in the embodiments, the reflective optical sensor / reflective optical sensor array is small and has good detection sensitivity, and can detect “at least one of position and toner density” of the toner pattern.

  Therefore, an image forming apparatus using these reflective optical sensors and reflective optical sensor arrays can realize good image formation.

1 is an explanatory diagram illustrating a color printer as one embodiment of an image forming apparatus. FIG. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating an optical scanning device. FIG. 6 is a diagram for explaining toner pattern detection. FIG. 6 is a diagram for explaining toner pattern detection. FIG. 6 is a diagram for explaining an example of a toner pattern. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating the comparative example of a reflection type optical sensor array. It is a figure for demonstrating the comparative example of a reflection type optical sensor array. It is a figure for demonstrating the comparative example of a reflection type optical sensor array. It is a figure for demonstrating the comparative example of a reflection type optical sensor array. It is a figure for demonstrating the comparative example of a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. FIG. 6 is a diagram for explaining an example of a toner pattern for position detection. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor array.

Hereinafter, the present invention will be described in accordance with embodiments.
FIG. 1 shows a schematic configuration of a color printer as an example of an image forming apparatus.

  The color printer 2000 is a tandem multicolor printer that superimposes toner images of four colors (black, cyan, magenta, and yellow) to form a full-color image. A toner image of a predetermined color is formed on each of 2030a, 2030b, 2030c, and 2030d, and these toner images are transferred onto a transfer sheet via an intermediate transfer belt 2040 and fixed to form a color image. .

  Around each of the four photosensitive drums, there are cleaning units 2031a, 2031b, 2031c, 2031d, charging devices 2032a, 2032b, 2032c, 2032d, developing rollers 2033a, 2033b, 2033c, 2033d, toner cartridges 2034a, 2034b, 2034c, 2034d is disposed below the photosensitive drums 2030a, 2030b, 2030c, and 2030d, and the intermediate transfer belt 2040 contacts the lower peripheral surface of each of the photosensitive drums in the counterclockwise direction with the upper peripheral surface thereof. It is provided so that it can rotate.

In FIG. 1, reference numeral 2042 indicates a transfer roller 2042, reference numeral 2050 indicates a fixing roller, reference numeral 2054 indicates a paper feed roller, and reference numeral 2056 indicates a registration roller pair.
Reference numeral 2058 denotes a paper discharge roller, reference numeral 2060 denotes a paper feed tray, reference numeral 2070 denotes a paper discharge tray, reference numeral 2080 denotes a communication control device, and reference numeral 2245 denotes a reflective optical sensor array.

  The above-described units are controlled in an integrated manner by the printer control apparatus 2090.

  In FIG. 1, three-dimensional orthogonal coordinates: XYZ are determined as shown in the figure. That is, the Y-axis direction is a direction orthogonal to the drawing and is a direction along the longitudinal direction of each photosensitive drum. The X-axis direction is a direction along the arrangement direction of the four photosensitive drums (the left-right direction in the figure), and the Z direction is the up-down direction in FIG.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  Each of the photosensitive drums 2033a to 2033d has a “photoconductive photosensitive layer” formed on the surface thereof, and is rotated in the direction of the arrow (clockwise) within the plane in FIG. 1 by a rotation mechanism (not shown).

  A charging device 2032a, a developing roller 2033a, and a cleaning unit 2031a are arranged in this order in the rotation direction along the peripheral surface of the photosensitive drum 2030a.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, and the cleaning unit 2031a are used as one set, and constitute an image forming station (hereinafter also referred to as “K station”) that forms a black image.

  Similarly, a charging device 2032b, a developing roller 2033b, a toner cartridge 2034b, and a cleaning unit 2031b disposed around the photosensitive drum 2030b are an image forming station (hereinafter referred to as “C station”) that forms a cyan image. (Also called).

  Similarly, a charging device 2032c, a developing roller 2033c, a toner cartridge 2034c, and a cleaning unit 2031c disposed around the photosensitive drum 2030c are also referred to as an image forming station (hereinafter referred to as “M station”) that forms a magenta color image. Construct).

  Similarly, a charging device 2032d, a developing roller 2033d, a toner cartridge 2034d, and a cleaning unit 2031d disposed around the photosensitive drum 2030d are also referred to as an image forming station (hereinafter referred to as “Y station”) that forms a yellow image. Construct).

  Each charging device uniformly charges the surface of the corresponding photosensitive drum.

The optical scanning device 2010, based on multi-color image information (black image information, cyan image information, magenta image information, yellow image information) from the host device, converts the light flux modulated for each color image information to the corresponding “charging”. Optical scanning is performed by irradiating the “surface of the photosensitive drum”.
By the optical scanning, the charge of the “light-irradiated portion” on the surface of each photosensitive drum disappears, and an electrostatic latent image corresponding to each color image information is formed on the surface of each photosensitive drum.
Each formed electrostatic latent image moves toward the corresponding developing roller as each photosensitive drum rotates. The configuration of the optical scanning device 2010 will be described later.

  The toner cartridges 2034a to 2034d contain black toner, cyan toner, magenta toner, and yellow toner, respectively.

The black toner stored in the toner cartridge 2034a is supplied to the developing roller 2033a. The cyan toner stored in the toner cartridge 2034b is supplied to the developing roller 2033b.
The magenta toner stored in the toner cartridge 2034c is supplied to the developing roller 2033c, and the yellow toner stored in the toner cartridge 2034d is supplied to the developing roller 2033d.

The peripheral surface of each developing roller is thinly and uniformly coated with toner from the corresponding toner cartridge as the roller rotates.
When the toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, the toner moves to and adheres to the “part irradiated with light” on the surface. That is, each developing roller attaches toner to the electrostatic latent image formed on the surface of the corresponding photosensitive drum, and visualizes it as a toner image.

The toner image obtained by development moves toward the transfer belt 2040 as the photosensitive drum rotates.
Although not described, there is also a method for detecting the toner density and / or toner position on the photosensitive drum after the toner adheres to the latent image by the developing roller.

  The yellow, magenta, cyan, and black toner images are sequentially transferred onto the transfer belt 2040 at a predetermined timing, and are superimposed to form a color image.

  In the following description, “the direction in which the toner image transferred onto the transfer belt 2040 moves” is referred to as “sub-direction”, and the direction orthogonal to the sub-direction (Y-axis direction) is referred to as “main direction”.

Recording paper is stored in the paper feed tray 2060.
A paper feed roller 2054 disposed in the vicinity of the paper feed tray 2060 feeds recording paper from the paper feed tray 2060 one by one toward the registration roller pair 2056.
The registration roller pair 2056 sends the recording paper toward the gap between the intermediate transfer belt 2040 and the transfer roller 2042 at a predetermined timing.

  The color image on the intermediate transfer belt 2040 is transferred onto the recording paper by the transfer roller 2042. The recording sheet on which the color image has been transferred is fixed with the color image by the fixing roller 2050 by the action of heat and pressure, sent to the discharge tray 2070 side via the discharge roller 2058, and discharged onto the discharge tray 2070. Are stacked sequentially.

  Each of the cleaning units 2031a to 2031d removes residual toner on the surface of the corresponding photosensitive drum 2030a to 2030d. The surface of each photosensitive drum from which the residual toner has been removed returns to the position facing the corresponding charging device again.

  The reflective optical sensor array 2245 is disposed on the “−X side” of the transfer belt 2040. The reflective optical sensor array 2245 will be described later.

  Next, the configuration of the optical scanning device 2010 will be described.

As shown in FIG. 2 to FIG. 5 as an example, the optical scanning device 2010 includes four light sources 2200a, 2200b, 2200c, 2200d, four coupling lenses 2201a, 2201b, 2201c, 2201d, four aperture plates 2202a, 2202b, 2202c, 2202d, four cylindrical lenses 2204a, 2204b, 2204c, 2204d, polygon mirror 2104, four fθ lenses 2105a, 2105b, 2105c, 2105d, eight folding mirrors 2106a, 2106b, 2106c, 2106d, 2108a, 2108b, 2108c, 2108d, 4 toroidal lenses 2107a, 2107b, 2107c, 2107d, 4 light detection sensors 2205a, 2205b, 2205c, 2205d, 4 Light detection mirror 2207A, equipped 2207b, 2207c, and 2207D, further includes a like (not shown) scanning control unit.
These are assembled at predetermined positions of the optical housing 2300 (see FIG. 5).

  A direction corresponding to the main scanning direction in the optical scanning is referred to as a “main scanning corresponding direction”, and a direction corresponding to the sub scanning direction is referred to as a “sub scanning corresponding direction”.

2 to 4, the direction along the optical axis of the coupling lens 2201a and the coupling lens 2201b is “w1 direction”, and the main scanning corresponding direction in the light source 2200a and the light source 2200b is “m1 direction”. To do.
Similarly, the direction along the optical axis of the coupling lens 2201c and the coupling lens 2201d is referred to as “w2 direction”, and the main scanning corresponding direction in the light source 2200c and the light source 2200d is referred to as “m2 direction”.
The sub-scanning corresponding direction in the light sources 2200a and 2200b and the sub-scanning corresponding direction in the light sources 2200c and 2200d are both the same direction as the Z-axis direction.

  The light source 2200b and the light source 2200c are disposed at positions separated from each other in the X-axis direction. The light source 2200a is disposed on the “−Z side” of the light source 2200b. The light source 2200d is arranged on the “−Z side” of the light source 2200c.

  The coupling lens 2201a is disposed on the optical path of the light beam emitted from the light source 2200a, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201b is disposed on the optical path of the light beam emitted from the light source 2200b, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201c is disposed on the optical path of the light beam emitted from the light source 2200c, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201d is disposed on the optical path of the light beam emitted from the light source 2200d, and makes the light beam a substantially parallel light beam.

Each of the opening plates 2202a to 2202d has an opening.
The light beam that has passed through the coupling lens 2201a is shaped through the opening of the aperture plate 2202a, and the light beam that has passed through the coupling lenses 2201b to 220d is shaped through the openings of the aperture plates 220b to 2202d.

  Cylindrical lenses 2204 a to 2204 d image the light beams that have passed through the respective apertures of the corresponding aperture plates 2202 a to 2202 d in the vicinity of the deflection reflection surface of the polygon mirror 2104 in the Z-axis direction.

  The polygon mirror 2104 has a four-stage mirror having a two-stage structure that is stacked in two stages in the rotation axis direction, and each mirror serves as a deflection reflection surface. The light beam from the cylindrical lens 2204a and the light beam from the cylindrical lens 2204d are deflected by the first-stage (lower) tetrahedral mirror, respectively, and the light beam from the cylindrical lens 2204b and the cylindrical light are deflected by the second-stage (upper) tetrahedral mirror. It arrange | positions so that the light beam from the lens 2204c may be deflected, respectively.

  Although not shown in the drawing, the first-stage quadrilateral mirror and the second-stage tetrahedral mirror are rotated by 45 degrees out of phase with each other, and writing scanning is performed alternately on the first and second stages. Is called.

  The light beams from the cylindrical lens 2204 a and the cylindrical lens 2204 b are deflected on the −X side of the polygon mirror 2104, and the light beams from the cylindrical lens 2204 c and the cylindrical lens 2204 d are deflected on the + X side of the polygon mirror 2104.

  Each of the fθ lenses 2105a to 2105d has a non-arc surface shape having such a power that the light spot moves at a constant speed in the main scanning direction on the surface of the corresponding photosensitive drum as the polygon mirror 2104 rotates. ing.

  The fθ lens 2105a and the fθ lens 2105b are arranged on the “−X side” of the polygon mirror 2104, and the fθ lens 2105c and the fθ lens 2105d are arranged on the “+ X side” of the polygon mirror 2104, respectively.

As shown in FIG. 5, the fθ lens 2105a and the fθ lens 2105b are stacked in the Z-axis direction, the fθ lens 2105a faces the first-stage four-sided mirror, and the fθ lens 2105b faces the second-stage four-sided mirror. is doing.
Similarly, the fθ lens 2105c and the fθ lens 2105d are stacked in the Z-axis direction, the fθ lens 2105c is opposed to the second-stage tetrahedral mirror, and the fθ lens 2105d is opposed to the first-stage tetrahedral mirror.

As shown in FIG. 5, the light beam from the cylindrical lens 2204a deflected by the polygon mirror 2104 is a light spot on the photosensitive drum 2030a via the fθ lens 2105a, the folding mirror 2106a, the toroidal lens 2107a, and the folding mirror 2108a. As the polygon mirror 2104 rotates, it moves in the longitudinal direction of the photosensitive drum 2030a and optically scans the photosensitive drum 2030a.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030a, and the rotational direction of the photosensitive drum 2030a is the “sub-scanning direction” on the photosensitive drum 2030a.

Similarly, the light beam from the cylindrical lens 2204b is deflected by the polygon mirror 2104 and irradiated to the photosensitive drum 2030b as a light spot via the fθ lens 2105b, the folding mirror 2106b, the toroidal lens 2107b, and the folding mirror 2108b, and the polygon mirror The photoconductor drum 2030b is optically scanned with the rotation of 2104.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030b, and the rotational direction of the photosensitive drum 2030b is the “sub-scanning direction” on the photosensitive drum 2030b.

  The light beam from the cylindrical lens 2204c is deflected by the polygon mirror 2104, and irradiated to the photosensitive drum 2030c as a light spot via the fθ lens 2105c, the folding mirror 2106c, the toroidal lens 2107c, and the folding mirror 2108c, and the polygon mirror 2104 rotates. Accordingly, the photosensitive drum 2030c is optically scanned. The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030c, and the rotational direction of the photosensitive drum 2030c is the “sub-scanning direction” on the photosensitive drum 2030c.

The light beam from the cylindrical lens 2204d is deflected by the polygon mirror 2104 and irradiated to the photosensitive drum 2030d as a light spot via the fθ lens 2105d, the folding mirror 2106d, the toroidal lens 2107d, and the folding mirror 2108d, and the polygon mirror 2104 rotates. Accordingly, the photosensitive drum 2030d is optically scanned.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030d, and the rotational direction of the photosensitive drum 2030d is the “sub-scanning direction” on the photosensitive drum 2030d.

  In each photosensitive drum, a scanning area in the main scanning direction in which image information is written is called an “effective scanning area” or an “image forming area”.

  Each folding mirror is arranged so that the optical path lengths from the polygon mirror 2104 to each photosensitive drum coincide with each other, and the incident position and the incident angle of the light flux on each photosensitive drum are equal to each other. .

  The cylindrical lens and the corresponding toroidal lens constitute a “surface tilt correction optical system in which the deflection point on the deflection reflection surface of the polygon mirror and the corresponding photosensitive drum surface are conjugated in the sub-scanning direction”. Yes.

The optical system arranged on the optical path between the polygon mirror 2104 and each photosensitive drum is also called a scanning optical system. In this embodiment, the scanning optical system of the K station is configured by the fθ lens 2105a, the toroidal lens 2107a, and the folding mirrors (2106a, 2108a).
Similarly, the scanning optical system of the C station is composed of the fθ lens 2105b, the toroidal lens 2107b, and the folding mirror (2106b, 2108b). The scanning optical system of the M station is composed of the fθ lens 2105c, the toroidal lens 2107c, and the folding mirror (2106c, 2108c). Each of these systems is configured, and a scanning optical system for the Y station is configured by the fθ lens 2105d, the toroidal lens 2107d, and the folding mirrors (2106d, 2108d).

  As shown in FIG. 5, the light detection sensor 2205a is deflected by the polygon mirror 2104 and a part of the light beam before starting writing out of the light beam passing through the scanning optical system of the K station passes through the light detection mirror 2207a. The light beam is deflected by the polygon mirror 2104 and part of the light beam before the start of writing enters the light detection sensor 2205b via the light detection mirror 2207b. .

Similarly, a part of the light beam before the start of writing out of the light beam deflected by the polygon mirror 2104 through the scanning optical system of the M station enters the light detection sensor 2205c via the light detection mirror 2207c. A part of the light beam before the start of writing out of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the Y station enters the light detection sensor 2205d via the light detection mirror 2207d.
Each of these light detection sensors outputs a signal (photoelectric conversion signal) corresponding to the amount of received light.

  The “scanning control device” detects the scanning start timing on the corresponding photosensitive drum based on the output signal of each light detection sensor.

  The image forming apparatus has been outlined above.

  Hereinafter, the reflective optical sensor array 2245 will be described.

  The reflective optical sensor array 2245 includes four reflective optical sensor arrays 2245a, 2245b, 2245c, and 2245d as shown in FIG. 6 as an example.

The reflective optical sensor array 2245a is disposed at a position facing the vicinity of the “+ Y side” end of the intermediate transfer belt 2040, and the reflective optical sensor array 2245d is disposed near the “−Y side” end of the intermediate transfer belt 2040. It is arranged at the opposite position.
The reflective optical sensor array 2245b is disposed on the “−Y side” of the detection sensor 2245a, and the reflective optical sensor array 2245c is disposed on the “+ Y side” of the reflective optical sensor 2245d.

  These four reflective optical sensor arrays 2245a to 2245d are arranged such that the intervals between the reflective optical sensor arrays are substantially equal with respect to the Y-axis direction.

The distance between each of the reflective optical sensor arrays 2245a to 2245d and the intermediate transfer belt 2040 is generally about several mm to about 10 mm due to restrictions in the image forming apparatus.
That is, unfixed toner adheres on the intermediate transfer belt 2040, and the intermediate transfer belt 2040 moves at a peripheral speed of several hundred mm / s. There is a concern that the reflective optical sensor array may come into contact, and there is a concern that the toner flying in the vicinity of the intermediate transfer belt may adhere to the light emitting portion, the light receiving portion, or the illumination or light receiving condensing lens.

  For this reason, it is necessary to provide a distance of several mm or more between the reflective optical sensor array and the intermediate transfer belt, depending on the running speed of the intermediate transfer belt and the “airflow design inside the image forming apparatus”.

  On the other hand, if the distance is too large, there are concerns that the “layout property” of the reflective optical sensor is deteriorated and the “sensitivity” is lowered.

  As an example, as shown in FIG. 7, with respect to the Y-axis direction, the center positions of the reflective optical sensor arrays 2245a to 2245d are Y1 to Y4, and the toner patterns facing the reflective optical sensor arrays 2245a to 2245d are respectively set. TP1 to TP4.

  TP1 is a yellow toner pattern, TP2 is a magenta toner pattern, TP3 is a cyan toner pattern, and TP4 is a black toner pattern.

  When toner density detection processing using the reflective optical sensor array 2245 (2245a to 2245d) is performed, the printer control device 2090 instructs the scan control device to form toner patterns TP1 to TP4.

  The scanning control device controls the Y station so that the yellow toner pattern TP1 is formed at the position Y1 on the photosensitive drum 2030d, and M so that the magenta toner pattern TP2 is formed at the position Y2 on the photosensitive drum 2030c. The station C is controlled so that the cyan toner pattern TP3 is formed at the position Y3 on the photosensitive drum 2030b, and the black toner pattern TP4 is formed at the position Y4 on the photosensitive drum 2030a. Control the station.

The yellow toner pattern TP1 formed by the Y station is at the position Y1 on the intermediate transfer belt 2040, and the magenta toner pattern TP2 formed by the M station is at the position Y2 on the intermediate transfer belt 2040, and the cyan toner pattern formed by the C station. The toner pattern TP3 is transferred to the position Y3 on the intermediate transfer belt 2040, and the black toner pattern TP4 formed by the K station is transferred to the position Y4 on the intermediate transfer belt 2040.
Hereinafter, when it is not necessary to distinguish the toner patterns, the toner patterns are collectively referred to as “toner pattern TP”.

As an example, the toner pattern TP has five rectangular patterns p1 to p5 (hereinafter simply referred to as “rectangular patterns”), as shown in FIG.
The rectangular patterns are arranged in a line along the traveling direction of the transfer belt 2040, and the gradation of the toner density is different. The length of each rectangular pattern in the Y-axis direction is Lp, and the length of the transfer belt 2040 in the traveling direction is Wp.

  The gradation of the toner density can be changed by adjusting the power of the light beam emitted from the light source, adjusting the duty of the driving pulse supplied to the light source, adjusting the developing bias, or a combination of these adjustments. .

As an example, as shown in FIGS. 9 to 11, the reflective optical sensor array 2245a includes 19 light emitting units (E1 to E19), 19 light collecting condenser lenses (LE1 to LE19), and 19 light receiving units. Part (D1-D19) and the processing apparatus which is not illustrated.
The light emitting units E1 to E19 are “semiconductor light emitting elements”, and the light receiving units D1 to D19 are photodiodes (or phototransistors).

  FIG. 9 shows a state in which the light emitting part and the light receiving part of the reflective optical sensor array 2245a are viewed from the X direction, FIG. 10 shows a state in which the reflective optical sensor array 2245a is viewed from the main direction (Z direction), and FIG. The detection light beams S1 to S19 emitted from the light emitting units E1 to E19 irradiate the intermediate transfer belt 2040, respectively.

  As shown in FIG. 9, the 19 light emitting portions E1 to E19 are arranged at equal intervals Le along the Y direction.

  In this example, an LED is used for each light emitting unit. Interval: Le is set to Le = 0.4 mm as an example. The illumination condenser lenses LE1 to LE19 individually correspond to the light emitting units E1 to E19 in a 1: 1 ratio.

  Each illumination condenser lens is disposed on the “+ X side” of the corresponding light emitting unit, and guides the light beam emitted from the light emitting unit toward the surface of the intermediate transfer belt 2040. For convenience of the following description, as shown in FIGS. 10 and 11, the light beams emitted from the light emitting units E1 to E19 and collected by the illumination condenser lenses LE1 to LE19 are “collection for illumination corresponding to each light emitting unit”. It is assumed that the light passes through the “optical lens only” and the intermediate transfer belt 2040 is irradiated as the detection light beams S1 to S19.

  The optical axis of each illumination condenser lens is parallel to the light emission axis of the light emitting surface of the corresponding light emitting section.

  The surface of the intermediate transfer belt 2040 is smooth and reflects most of the light irradiated on the surface. The light receiving parts D1 to D19 detect the light emitted from the light emitting parts E1 to E19 when the light for detection from the light emitting parts E1 to E19 is irradiated on the “belt surface other than the toner pattern”. It receives light "only specularly reflected light from the belt surface".

  The size of the light spot that each detection light forms on the surface of the intermediate transfer belt 2040 is 0.2 mm in diameter as an example. The size of the light spot by the detection light in the conventional reflective optical sensor is usually about 2 to 3 mm in diameter.

Each illumination condenser lens includes a spherical lens having a condensing function in the main direction (Y-axis direction in the figure) and the sub-direction (Z-axis direction in the figure), and the main direction (Y-axis direction in the figure). And anamorphic lenses having different powers in the sub-direction (Z-axis direction in the figure) can be used.
If it shows as an example, the magnitude | size of each condensing lens for illumination is diameter: 0.4mm. That is, the arrangement pitch of the light emitting portions E1 to E19 and the arrangement pitch of the illumination condenser lenses LE1 to LE19 are made equal.

The size of the light spot of the detection light is not limited to the above, but is preferably smaller than the arrangement pitch of the light emitting portions. The shape of the condenser lens for illumination is not limited to a circle (diameter: 0.4 mm), but may be a rectangle having an arrangement pitch of 0.4 mm.
By increasing the size in the direction (Z direction) perpendicular to the arrangement direction (Y direction), it is possible to “enhance the light amount of the light spot as compared to the case of a circle”.

  A specific example will be described below.

"Example 1"
Regarding the “optical layout guided onto the intermediate transfer belt 2040 by the illumination condenser lens”, the light emitting part Ei (i = 1 to 19), the light receiving part Di (i = 1 to 19), and the irradiation lens LEi (i = 1-19) and an optical path diagram (XZ sectional view) from which only the intermediate transfer belt 2040 is taken out are shown in FIG.

  In the figure, “L0” is the distance from the light emitting portion Ei to the illumination condenser lens LEi, “L1” is the thickness of the illumination condenser lens LEi, and “L2” is from the illumination condenser lens LEi to the intermediate transfer belt 2040. In this example, L0 = 1 mm, L1 = 0.5 mm, and L2 = 5 mm.

  The light emitting unit Ei is an LED, and the wavelength of emitted light is a center wavelength: 850 nm and a half width: 30 nm. The size of the light emitting portion Ei was “a substantially square shape with a side of 40 μm”.

The light receiving part Di is a photodiode (PD), and the wavelength characteristic of the light receiving sensitivity is formed to have a peak at about 850 nm, and the light receiving efficiency peak is matched with the light emission center wavelength of the light emitting part Ei. It is increasing.
The light receiving part Di was set to “a substantially square shape with a side of 360 μm”.

  The arrangement direction of the light receiving portions Di in the arrangement direction (direction perpendicular to the drawing: Y-axis direction) requires an “arrangement pitch or space for wiring pattern” between adjacent PDs. It cannot be larger. As a general space, 10% of the arrangement pitch was secured to 360 μm.

  The illumination condensing lens LEi is made of “glass material having a refractive index of 1.5 at the center wavelength” as described above, and the light emitting portion side is convex as shown in the drawing, and its radius of curvature is R = 0.53 mm, an intermediate transfer belt. The side is a plane.

The illumination condensing lens LEi has the same shape in the arrangement direction: 0.4 mm and the arrangement orthogonal direction: 0.44 mm, and all the lenses are integrally formed of the glass material.
The optical axis of the illuminating condenser lens LEi is orthogonal to the light emitting surface of the light emitting portion Ei, and is shifted by a shift amount (Δ): 0.045 mm in the −Z direction, that is, toward the photodiode (PD) that is the light receiving portion Di. Has been.

In this optical layout, the light emitted from the light emitting portion Ei is converted into substantially parallel light by the illumination condenser lens LEi and guided to the intermediate transfer belt 2040.
The 19 light emitting portions Ei and the light receiving portions Di are integrally formed on a substrate (not shown) by a semiconductor process to form an “integrated light emitting / receiving device”.
The distance between the centers of the light emitting part Ei and the light receiving part Di in the Z direction is 500 μm.

The light emitting element and the light receiving element used in the conventional reflective optical sensor are separate from each other, such as a “bullet type element sealed with a resin lens” or a surface mount type element (SMD: Surface Mount Device). These elements are provisional “the light emitting part in the light emitting element or the light receiving part in the light receiving element is sealed with a resin lens even if it is small”, and the size of the element is on the order of mm.
It is impossible to dispose the light emitting element and the light receiving element as separate bodies close to 1 mm or less.

  On the other hand, in the reflective optical element array of the present invention, the light emitting part and the light receiving part which do not have the resin lens (sealing material) are integrally formed on the same substrate, so that the light emitting part and the light receiving part as described above. It is possible to make the space | interval of Z direction close to 1 mm or less.

  In FIG. 12, light from the light emitting portion Ei, which is an LED, is divergently emitted in a so-called “Lambert distribution” in a direction perpendicular to a substrate surface (not shown) (a direction parallel to the light emitting axis). A light ray (hereinafter referred to as “center light ray”) radiated from the center of the light emitting portion in the direction of the normal line (light emitting axis) of the light emitting portion is indicated by a thick solid line, and a peripheral light ray in the XZ section is indicated by a thin solid line.

  The central light beam emitted from the center of the light emitting portion Ei along the light emitting axis is refracted to the “−Z side” at the first surface (light emitting portion side surface) of the illumination condenser lens LEi and guided to the intermediate transfer belt 2040. The

  The central ray regularly reflected by the intermediate transfer belt 2040 is incident on the center of the light receiving part Di (intersection of the light receiving axis and the light receiving surface) in the reference state shown in the drawing. That is, in the reference state, the light emitting part and the light receiving part for the central ray are separated by 500 μm in the Z direction.

  In this reference state, an incident angle at which the central light beam emitted from the light emitting portion Ei enters the intermediate transfer belt 2040 (an angle formed by the normal beam and the central light beam set at the incident position on the intermediate transfer belt surface) is an incident angle: Θa. To do.

  In Specific Example 1, Θa = 2.44 degrees.

"Example 2"
In Specific Example 2 shown in FIG. 13, the light beam emitted from the light emitting portion Ei is converted into a convergent light beam by the illumination condenser lens LEi and guided to the intermediate transfer belt 2040. To do this, for example, the refractive power of the illumination condenser lens LEi may be increased.
The condensing lens LEi for illumination used in this specific example 2 is a convex flat lens convex on the light emitting portion Ei side, and has a radius of curvature of the convex surface on the light emitting portion side: R = 0.50 mm. The light emitting unit Ei is shifted in the −Z direction in parallel with the light emitting axis.

The shift amount (Δ) is 0.042 mm.
The curvature radius of the convex surface: R is reduced from R = 0.53 mm in Specific Example 1 to 0.5 mm, so that the refractive power of the condenser lens for illumination LEi becomes strong, and the light beam after passing through the lens becomes a converged light beam. ing.

Since the radius of curvature R is as described above, the optical path of the central ray is shifted from the center of the light receiving portion Di in the same optical layout as that of the first specific example. Therefore, the shift amount in the −Z direction of the condenser lens LEi for illumination is: Δ is changed to a value smaller than the value of the first specific example: 0.042 so that the central ray reaches the center of the light receiving part Di in the reference state.
All other optical layout conditions are the same as in the first specific example.

  Incident angle: Θa = 2.41 degrees. By reducing the shift amount: Δ, the angle of refraction of the central ray by the illumination condenser lens is smaller than in the case of the first specific example, and thus the incident angle: Θa is smaller than that in the first specific example.

  As is clear from the specific examples 1 and 2, the degree of divergence / convergence of the light beam and the incident angle: Θa when the light beam emitted from the light emitting unit LEi is guided to the intermediate transfer belt 2040 can be adjusted, and the small incident angle. : Θa can be realized.

"Example 3"
Specific example 3 shown in FIG. 14 is obtained by changing the distance L2 from the illumination condenser lens LEi to the transfer belt 2040 based on the optical layout of specific example 1.
The illumination condensing lens LEi is the same as in the first specific example, and the distance L0 is also the same as in the first specific example. The light beam emitted from the light emitting portion Ei is converted into a substantially parallel light beam by the light collecting lens LEi. Is done.

  In specific example 3, the distance was set to L2 = 3 mm.

  Since the position (incident position) at which the central ray is specularly reflected on the intermediate transfer belt 2040 changes as the distance “L2” is made shorter than those in the first and second examples, the position of the central ray incident on the light receiving unit Di is changed. Is shifted from the center of the light receiving unit to the Z-axis side (light emitting unit side) than in the case of the specific example 1.

In the third specific example, considering this point, the shift amount Δ in the −Z direction of the condensing lens LEi for illumination: Δ is changed from 0.045 mm in the first specific example to 0.067 mm, so that the proof condensing is performed. By reducing the angle of refraction of the central beam by the lens LEi, the central beam reflected by the surface of the intermediate transfer belt reaches the “center of the light receiving part Di”.
All other optical layout conditions are the same as in the first specific example.

  Incident angle in specific example 3: Θa = 3.64 degrees.

  As is clear from the specific examples 1 and 3, the small incident angle: Θa can be realized by adjusting the distance: L2, that is, the “distance between the reflective optical sensor array and the intermediate transfer belt: L2”.

Example 4
Specific example 4 shown in FIG. 15 is based on the optical layout of specific example 1, and the illumination condenser lens LEi has a thickness L1 and a distance from the illumination condenser lens LEi to the transfer belt 2040: L2. This is a case where it is made even smaller than the specific example 3.

That is, in the specific example 4, the thickness of the condenser lens for illumination LEi: L1 = 0.2 mm, L2 = 2.3 mm.
The radius of curvature of the convex surface on the light emitting portion side of the light collecting lens LEi: R is R = 0.53 mm as in the first specific example, the lens material is the same as in the first specific example, and the light collecting condensing lens is flat. It is a convex lens.
Therefore, the refractive power of the illumination condenser lens is not different from that of the first specific example, and the light beam emitted from the light emitting portion Ei is made into a substantially parallel light beam by the illumination condenser lens LEi.

  With the change of the distance: L1 and L2, the shift amount in the −Z direction of the condenser lens LEi for illumination is changed to Δ = 0.089 mm, and the central ray reflected by the intermediate transfer belt 2040 in the reference state is the light receiving unit. The center of Di was reached.

  All other optical layout conditions are the same as in the first specific example.

  In Example 4, the distance from the light emitting portion Ei to the transfer belt 2040: L0 + L1 + L2, that is, the “space for installing the reflective optical sensor array” can be substantially halved from 6.5 mm in Example 1 to 3.5 mm. ing.

In Specific Example 4, the incident angle is Θa = 4.86 degrees.
The range of the distance L2 from the illumination condenser lens LEi described above to the transfer belt 2040 is preferably about 2 mm to 10 mm, and more preferably 4 mm to 7 mm.

  In the specific examples 3 and 4, the example in which the distance L2 is decreased is shown, but it is needless to say that the incident angle: Θa can be decreased by increasing L2.

  However, as described above, the distance L2 from the intermediate transfer belt 2040 to the intermediate transfer belt 2040 of the illuminating condenser lens of the reflective optical sensor array is practically less than several mm due to restrictions in the image forming apparatus. Therefore, as the specification of the reflective optical sensor array, it is sufficient to satisfy the optical layout of the specific example 4.

  In the reflective optical sensor / reflective optical sensor array according to the present invention, the incident angle: Θa is 10 degrees, more preferably smaller than 5 degrees.

  Here, the significance of reducing the incident angle: Θa will be described.

  As described in the specific example described above, the positional relationship among the light emitting part, the light receiving part, the illumination condenser lens, and the surface of the intermediate transfer belt is such that the central ray from the light emitting part moves to the center of the light receiving part in the “reference state”. It is set to enter. That is, the distance between the light receiving portion and the intermediate transfer belt surface (supporting medium surface) is assumed to be constant in the “reference state”.

When the carrying medium is an intermediate transfer belt as in the above example, the belt surface fluctuates in a direction perpendicular to the belt surface due to the “flapping” of the belt, the eccentricity of the driving roller, etc. as the intermediate transfer belt runs. .
Even when the carrier medium is a photosensitive drum, the photosensitive surface varies in the direction perpendicular to the photosensitive surface due to the rotation of the photosensitive drum due to the eccentricity of the rotating shaft and the processing accuracy of the drum diameter.

  In relation to the above description, this means that the distance between the surface of the light receiving unit and the intermediate transfer belt (the size of “L0 + L1 + L2” in the above description varies).

  Therefore, in order to maintain the required detection accuracy in the reflection type optical sensor or the reflection type optical sensor array, it is necessary to have a margin for the variation in the distance.

Here, the distance between the surface of the carrier medium and the surface of the light receiving unit is “L”, and the variation amount of the surface of the carrier medium is ± δ.
Since regular reflection on the surface of the carrier medium is considered, the reflection angle is equal to the incident angle: Θa.

Then, in the reference state, the “distance in the Z-axis direction: Za” between the incident position of the central ray incident on the surface of the carrier medium at the incident angle: Θa and the position where the reflected central ray enters the surface of the light receiving unit is
Za = L · tanΘa
It becomes.
In this state, if the distance: L varies by ± δ, the amount of deviation of the incident position of the central ray on the light receiving portion: ΔZa is
ΔZa = ± 2δ · tanΘa
It becomes.

  In a general image forming apparatus, “δ” is known to be about 0.5 mm or less.

  Since the value of tan Θa for Θa = 10 degrees is tan10 ° = 0.176, it becomes ± 88 μm for δ = ± 0.5 mm.

As described above, if a light receiving portion Di having a “substantially square shape with a side of 360 μm” is used and the central ray is incident on the central portion of the light receiving portion in the reference state, the light receiving portion is centered in the Z direction. On the other hand, it has a light receiving region of ± 180 μm.
Under this condition, with respect to the fluctuation amount of “δ”: ± 0.5 mm, the range of deviation of the central ray incident on the light receiving unit is the range of the light receiving region: ± 180 μm with respect to the center. It is possible to detect the toner pattern by effectively receiving regular reflection light.

  Incident angle: If Θa is smaller than 5 degrees, about ± 1 mm is allowed for the above-mentioned δ, and the margin of detection accuracy becomes sufficiently large.

  In order to reduce the incident angle: Θa without increasing the distance between the light emitting unit and the light receiving unit and the surface of the carrier medium, it is necessary to bring the light emitting unit and the light receiving unit close to each other. The limit which can be made becomes a substantial lower limit of the incident angle: Θa.

  Factors that determine the proximity limit of the light emitting unit and light receiving unit include, for example, that if the two are too close together, the influence of irradiation light that directly enters the light receiving unit from the light emitting unit cannot be ignored, or because of margin and wiring required for processing There is a need to secure a space for the other.

  The above description will be described in more detail by taking the case of the specific example 4 described above as an example.

  FIG. 16 shows only the central ray in the optical layout of the specific example 4 shown in FIG. As described above, the incident angle is Θa = 4.86 degrees.

  FIG. 16A shows the case of the reference state. When the Z coordinate of the central ray is Z = 0 mm on the light emitting portion Ei, the incident position on the light receiving portion Di is Z = −0.504 mm, and It is located at the substantial center (as described above, the center-to-center distance between the light emitting unit center and the light receiving unit center is 500 μm).

  FIG. 16B shows a state in which the intermediate transfer belt 2040 as a carrying medium is displaced by −1 mm in the X direction. At this time, the incident position of the central ray is Z = −0.334 mm on the light receiving part Di. Since the size of the light receiving portion Di is 360 μm, the end of the light receiving portion in the Z direction is (−0.5 mm + 0.18 mm =) − 0.32 mm, and the central ray is incident near the end in the light receiving portion.

  FIG. 16C shows a state where the intermediate transfer belt 2040 has changed by +1 mm in the X direction. At this time, the incident position of the central ray is Z = −0.675 mm on the light receiving part Di.

  The other light receiving portion end in the Z direction is (−0.5 mm−0.18 mm =) − 0.68 mm, and the central ray enters near the end in the light receiving portion.

As described above, when the incident angle: Θa is 5 degrees or less, the central light beam reflected by the surface of the carrier medium is received even when the surface of the carrier medium is changed by about ± 1 mm in the general image forming apparatus described above. The light enters the light receiving area of the part Di.
When the central ray is incident on the end of the light receiving portion region, the light flux entering the light receiving portion (the light regularly reflected from the transfer belt) is approximately ½. % Detection efficiency ”.
Of course, if the variation in the position of the carrier medium is about 0.5 mm or less, the light flux entering the light receiving unit becomes 3/4 or more, and thus a decrease in detection efficiency can be sufficiently suppressed.

  FIG. 17 shows an optical path when “there is no illumination condenser lens LEi” in the above-described specific example 1 (FIG. 12).

As described above, the light beam emitted from the light emitting unit Ei, which is an LED, diverges in a so-called Lambertian distribution in a direction perpendicular to the substrate.
In FIG. 17, since there is no illumination condenser lens LEi, the light beam emitted from the center of the light emitting unit along the optical axis (the above-mentioned central light beam) is regularly reflected by the intermediate transfer belt 2040 and returns to the center of the light emitting unit. The light receiving unit Di cannot be reached.

The light rays shown in FIG. 17 are “oblique light rays” among the light rays radiated from the light emitting portion when they are regularly reflected by the intermediate transfer belt 2040 and enter the light receiving portion Di.
Assuming that the incident angle at which this “oblique light ray” is incident on the surface of the intermediate transfer belt 2040 is “Θb”, in FIG. 17, Θb = arctan (0.25 / 6.5) = 2.20 °, which is a specific example. With respect to the incident angle at 1: Θa (= 2.44 °), Θb <Θa.

  As is clear from the above description, the smaller the incident angle of the light beam incident on the carrier medium, the better. From this point of view, the case of FIG. 17 without the illumination condenser lens LEi is better. However, in order to improve the detection efficiency, an illumination condenser lens is required.

FIG. 18 shows the peripheral rays that can reach the light receiving unit Di.
As is apparent from a comparison between FIG. 18 and FIG. 12, the amount of light that can be emitted from the light emitting portion Ei can reach the light receiving portion Di, that is, the detection efficiency varies greatly depending on the presence or absence of the illumination condenser lens. As shown in FIG. 12, it is necessary to provide the illumination condenser lens LEi in order to improve the detection efficiency.

  When the illumination condenser lens LEi is used, the incident angle: Θa is slightly larger than the incident angle: Θb, but “detection efficiency beyond that” can be improved even when the incident angle is increased. Furthermore, a sufficiently small incident angle (= 5 °) can be realized even when the incident angle is Θa larger than the incident angle: Θb. It is apparent from the Lambertian distribution that the intensity of the central ray is larger than that of the “oblique ray”.

  FIG. 19 shows an optical path of an oblique light beam when the illumination condenser lens LEi is not provided in the specific example 2 (FIG. 13).

  Similarly to FIG. 17, when there is no illumination condenser lens, the “oblique light” emitted from the light emitting portion Ei is regularly reflected by the intermediate transfer belt 2040 and incident on the intermediate transfer belt 2040 when received by the light receiving portion Di. Angle: Θb is Θb = arctan (0.25 / 6.5) = 2.20 °, again Θb <Θa (= 2.41 °).

  FIG. 20 shows an optical path of oblique rays when the illumination condenser lens LEi is removed from the specific example 3 (FIG. 14).

  Similarly to the above, also in FIG. 20, the incident angle: Θb = arctan (0.25 / 4.5) = 3.18 °, and Θb <Θa (= 3.64 °).

  FIG. 21 shows an optical path of oblique rays when the illumination condenser lens LEi is removed from the specific example 4 (FIG. 15).

  In this case as well, Θb = arctan (0.25 / 3.5) = 4.09 °, and Θb <Θa (= 4.86 °).

  Thus, all of the specific examples 1 to 4 satisfy “Θb <Θa”.

"Example 5"
Specific example 5 shown in FIG. 22 is a case where a light receiving condensing lens is further provided in the above-described specific example 1 (FIG. 12).

  The light receiving condensing lens LDi is provided corresponding to each light receiving part Di, similarly to the illumination condensing lens LEi. A plurality of illumination condenser lenses LEi and light reception condenser lenses LDi are arrayed in the Y-axis direction orthogonal to the drawing, and the arrayed elements are integrated with each other.

  The light receiving condenser lens LDi is disposed at the same position as the illumination condenser lens LEi in the X direction, the distance in the X direction from the transfer belt 2040 to the illumination condenser lens LDi is 5 mm, and the light receiving condenser lens LDi. Is 0.5 mm, and the distance in the X direction from the light receiving condensing lens LDi to the light receiving portion Di is 1 mm.

The light receiving condensing lens lens LDi is made of the same glass material as that of the illumination condensing lens LEi, the light emitting portion side is a convex surface, the radius of curvature is R = 0.53 mm, and the intermediate transfer belt 2040 side is a flat surface.
The lens size of the light receiving condensing lens LDi is 0.4 mm in the arrangement direction (Y direction) and 0.44 mm in the Z direction. The light receiving condensing lenses LDi have “all the same shape” and are integrally formed as described above.
The light receiving condensing lens LDi is shifted in the + Z direction with respect to the normal line (light receiving axis) at the center of the light receiving portion Di, and the shift amount is ΔD = 0.015 mm.
The other optical layout is the same as FIG.

In this optical layout, the light emitted from the light emitting portion Ei is converted into substantially parallel light by the illumination condenser lens LEi and irradiated to the intermediate transfer belt 2040, and the light regularly reflected on the belt surface is substantially parallel light. As it is, it is coupled to the light receiving condensing lens LDi and condensed on the light receiving portion Di.
By providing the light receiving condensing lens LDi, the specularly reflected light beam can effectively reach the light receiving portion, and the detection efficiency is improved.

FIG. 23 shows a state where the intermediate transfer belt 2040 has moved about ± 1 mm in the X direction.
23A shows a state when the intermediate transfer belt 2040 has moved by −1 mm in the X direction, and FIG. 23B shows a state when the intermediate transfer belt 2040 has moved by +1 mm in the X direction.

  Since the light beam applied to the intermediate transfer belt 2040 is a substantially parallel light beam, the light beam coupled to the light receiving condensing lens LDi is effectively condensed on the light receiving unit Di. Accordingly, it is possible to suppress a decrease in detection efficiency when a change in the position of the transfer belt occurs.

As described above, the illumination condensing lens LEi and the light receiving condensing lens LDi can be arrayed and integrally formed.
As an advantage of forming them integrally, each of the individual lenses must be aligned. For example, if the 19 illumination lenses LEi and the 19 light receiving lenses LDi can be integrated into one unit, once. The positioning accuracy of the light emitting part, the light receiving part, the illumination condenser lens, and the light receiving condenser lens can be greatly improved. Reduction) can be suppressed.

  Hereinafter, the “toner density detection process” using the reflective optical sensor array 2245 will be described. Before that, the “toner position detection process” will be described.

As shown in FIG. 24, the toner position detection (toner pattern position detection) is usually performed “prior to toner density detection”.
FIG. 24 is a view of the reflective optical sensor array 2245 as viewed from the X direction (a direction orthogonal to the surface of the intermediate transfer belt).
As shown in FIG. 25, the position detection pattern PP1 used for toner position detection is linear patterns LPY1, LPM1, LPC1, LPB1 parallel to the main direction (Y direction in the figure), and is oblique to the main direction. The line patterns LPY2, LPM2, LPC2, and LPB2 are inclined to each other.

  The line patterns LPY1 and LPY2 form a pair and are formed of yellow toner. Similarly, the line patterns LPM1 and LPM2 are paired and formed with magenta toner, the line patterns LPC1 and LPC2 are paired and formed with cyan toner, and the line patterns LPB1 and LPB2 are paired with black toner. Formed with.

  The “line pattern pairs” of these color toners are formed at regular intervals in the sub-direction (Z direction in the figure). That is, if these pairs are arranged at regular intervals in the sub direction, the patterns of the yellow to black toners have an “appropriate positional relationship in the sub direction”.

  In FIG. 25, symbols E8 to E12 indicate a part of the array of light emitting units.

  In order to detect whether or not the positional relationship in the sub-direction is appropriate, the position detection pattern PP1 approaches the reflective optical sensor array (showing the light emitting units E8 to E18) as shown in FIG. The timing is measured and, for example, the light emitting unit E10 is continuously lit at an appropriate timing.

  In accordance with the movement of the position detection pattern PP1, the detection light from the light emitting unit E10 is displaced in the sub direction (Z direction) relative to the surface of the carrier medium, and the detection light spots are formed by the linear patterns LPY1 to LPB1. Irradiate sequentially.

When the detection light irradiates the line pattern, the time interval at which the detection light irradiates the four line patterns can be detected by temporally tracking the outputs of the light receiving units D1 to D19.
If this time interval is equal, the positional relationship in the sub-direction between the toner patterns of each color is appropriate, and if the time interval is not equal, there is a deviation in the mutual positional relationship, and the amount of deviation can also be known. The timing of the optical scanning start can be controlled so as to correct the deviation.

  The “deviation in the main direction between toner patterns” can be detected as follows. The detection in this case will be described with reference to FIGS. 26 (2) and (3) for the case of a yellow toner pattern.

  FIG. 26 (2) shows a case where the yellow toner image is at an appropriate position in the main direction (Y direction in the figure). At this time, the spot line pattern LPY1 of the detection light from the light emitting unit E10 is irradiated. Let T be the time until irradiation with the line pattern LPY2.

  FIG. 26 (3) shows the case where the yellow toner image is shifted by ΔS in the main direction. Since the line pattern LPY2 is inclined with respect to LPY1, the time from when the spot of the detection light from the light emitting unit E10 irradiates the line pattern LPY1 to the line pattern LPY2 is T + ΔT, which is appropriate. The amount of deviation in the main direction can be known from the time at a correct position: difference from T: ΔT.

That is, if the angle formed by the line pattern LPY2 in the main direction is “θ” and the moving speed in the sub direction of the transfer belt 2040 as the support member is V,
ΔS · tanθ = V · ΔT
Therefore, the deviation amount ΔS in the main direction is
ΔS = V · ΔT · cotθ
Can know as.

In addition, the detection can be performed by “sequentially lighting a plurality of light emitting units”.
For example, in FIG. 26, the light emitting units E9 to E11 are repeatedly turned on sequentially such as E9 to E10 to E11 and E9 to E10 to E11.

In this repeated sequential light emission, the outputs of the light receiving parts D1 to D19 when the light emitting part E9 is lit are temporally tracked, and the outputs of the light receiving parts D1 to D19 when the light emitting part E10 is lit are temporally tracked. Then, by tracking the outputs of the light receiving parts D1 to D19 when the light emitting part E11 is lit, “three output signals when the light emitting part position is slightly shifted” can be obtained.
By averaging these three output signals, it is possible to know the improvement of measurement accuracy and the influence of positional deviation.

  Next, “toner density detection processing” using the reflective optical sensor array 2245 will be described. As the reflective optical sensor array, the reflective optical sensor array described with reference to FIG. 22 is used.

  The printer control device 2090 shown in FIG. 1 illuminates the transfer belt 2040 by sequentially lighting the light emitting portions E1 to E19 of the respective reflection type optical sensor arrays 2245a to 2245d.

  The signal processing device of each reflective optical sensor array obtains the received light amount of each light receiving unit individually based on the output signal of each light receiving unit, and stores the obtained received light amount in a memory (not shown).

The printer control device 2090 designates the size: Lp and position of the toner pattern irradiated to the detection lights S9 and S10 (light emitted from the light emitting units E9 and E10) for each color with respect to the scanning control device. To instruct the formation of a toner pattern.
Here, Lp = 1.0 mm. When the toner pattern has this size, it is irradiated with at least one detection light.

The printer control device 2090 sequentially turns on the light emitting units E1 to E19 of each reflective optical sensor.
At this time, when attention is paid to the light emitting parts E7 to E12, as shown in FIGS. 27A to 27C, the detection lights S7 to S12 emitted from the light emitting parts E7 to E12 are corrected by the transfer belt. The light is reflected and guided to the corresponding light receiving parts D7 to D12.
FIG. 27A shows the reflective optical sensor viewed from the sub-direction, and FIG. 27B shows the detection light S1 to S19 emitted from the light emitting portions E1 to E19 entering the transfer belt. FIG. 27C shows a state where the detection light beams S1 to S19 regularly reflected by the transfer belt are received by the light receiving portions D1 to D19.

  At this time, it is assumed that the amount of received light in the light receiving portions D7 to D12 is as shown in FIG.

When the rectangular toner pattern is positioned on the front side of the reflective optical sensor array, the toner pattern TP1 is “for detection from the light emitting portions E9 and E10” as illustrated in FIGS. 27 (e) to 27 (g). In the case of “position irradiated with the spots of the light S9 and S10”, the detection light emitted from the light emitting parts other than the light emitting parts E9 and E10 is regularly reflected on the surface of the intermediate transfer belt, and is shown in FIG. As shown in f), the light is received by the corresponding light receiving portions.
On the other hand, the detection lights S9 and S10 emitted from the light emitting units E9 and E10 irradiate the toner pattern TP1 as shown in FIG. 27 (e), and detect as shown in FIG. 27 (f). The working lights S9 and S10 are regularly reflected and diffusely reflected on the surface of the toner pattern TP1.

Hereinafter, for the sake of convenience, specularly reflected light is also referred to as “regularly reflected light”, and diffusely reflected light is also referred to as “diffuse reflected light”.
FIG. 27E shows a state in which the detection lights S1 to S19 emitted from the light emitting portions E1 to E19 enter the surface of the intermediate transfer belt 2040 and the toner pattern TP1, and FIG. 27F shows the intermediate transfer belt. The detection light specularly reflected by the surface 2040 and the detection light specularly and diffusely reflected by the toner pattern TP1 are received by the light receiving portions D1 to D19.

  FIG. 27 (g) shows an example of the amount of light received by the light receiving portions D7 to D12 at this time. The LED 7 to LED 12 are the light emitting units E7 to E12.

  As shown in FIG. 27 (g), when only the light emitting unit E9 is lit, the regular reflection component received by the light receiving unit D9 is reduced by the influence of diffuse reflection compared to the case shown in FIG. 27 (d). On the other hand, the diffusely reflected light is also received by the light receiving parts other than the light receiving part D9. When only the light emitting unit E10 is turned on, the regular reflection component received by the light receiving unit D10 is reduced due to the influence of diffuse reflection, compared to the case shown in FIG. It is also received by light receiving parts other than D10.

Therefore, when viewing the outputs of the light receiving parts D1 to D19, in the state where the light emitting part E9 emits light, the light receiving amount of the light receiving part D9 is low, and the outputs at the other light receiving parts are values other than zero.
In a state where the light emitting unit E10 emits light, the amount of light received by the light receiving unit D10 is low, and the output from other light receiving units is a value other than zero.
From this result, it can be seen that the toner pattern TP1 is at a position irradiated by the light emitting portion E9 and the light emitting portion E10. At this time, if the output of the light receiving unit D9 in a state where the light emitting unit E9 emits light is smaller than the output of the light receiving unit D10 in a state where the light emitting unit E10 emits light, the toner pattern is “closed to the light emitting unit E9. You can see that it is on the side.

  In this way, although the accuracy is inferior to the position detection using the “position detection pattern”, the position of the toner pattern TP1 in the main direction can also be detected with the accuracy of the “light emitting portion arrangement pitch”.

If it is found that the position of the toner pattern TP1 in the main direction is “predetermined within a certain range”, it is not necessary to turn on all the light emitting parts E1 to E19, and the toner pattern TP1 exists around the toner pattern TP1 in the main direction. It is only necessary to turn on the light emitting unit.
For example, all the light emitting portions E1 to E19 are turned on only for the first sequential lighting, and from the second time, the range of the presence of the toner pattern TP1 is known to some extent as a result of the first sequential lighting. It is possible to detect the position by lighting the part.

  As another method, there is a method using a “preliminary detection toner pattern” for knowing the position of the toner pattern by the preliminary operation.

  In general, “regular reflection light” in the reflection of a toner pattern decreases in proportion to an increase in toner density, and “diffuse reflection light” increases in proportion to an increase in toner density.

As the toner pattern TP1, an arrangement of “a plurality of toner patterns having different toner concentrations” as shown in FIG. 24 is considered. As shown in FIG. 28, the toner pattern TP1 is “a spot of detection light from the light emitting portions E9 and E10”. Let's consider the case where it is at the “irradiated position”.
The reflective optical sensor array is assumed to be that shown in FIG.
The light emitting unit to be lit is only E10, and attention is paid to the amount of light received by the light receiving units D7 to D12.
The plurality of toner patterns TP1 are designated as p1, p2, p3, p4, and p5 in order from the lowest toner density pattern.

  FIG. 28A shows a state in which the detection lights S1 to S19 emitted from the light emitting portions E1 to E19 are incident on the transfer belt and / or the toner pattern TP1, and FIG. The detection light that has been specularly reflected and the detection light that has been specularly reflected and diffusely reflected by the toner pattern TP1 are received by the light receiving portions D1 to D19.

  FIG. 28C shows an example of the amount of received light detected by the light receiving portions D7 to D12 when the light emitting portion E10 is turned on.

  It can be seen that as the toner density of the toner pattern irradiated with the detection light increases, “the amount of detected light received by each light receiving portion decreases”. Based on the magnitude relationship of the detected light reception amount, the toner density can be determined. This detected amount of received light is stored in a memory (not shown).

The printer control device 2090 shown in FIG. 1 determines whether or not the density of the yellow toner is appropriate based on the amount of received light received from the processing device of the reflective optical sensor array 2245a, and determines whether the density of the yellow toner is from the processing device of the reflective optical sensor array 2245b. Based on the detected amount of received light, whether or not the density of the magenta toner is appropriate. Based on the detected amount of received light from the processing device of the reflective optical sensor array 2245c, whether or not the density of the cyan toner is appropriate is determined. Whether the density of the black toner is appropriate or not is determined based on the amount of received light received from the processing device.
The printer control device 2090 controls the development processing system of the corresponding station so as to be appropriate according to the suitability of each toner density.

  As is clear from the above description, in the image forming apparatus 2000 (FIG. 1) according to this embodiment, the four reflective optical sensor arrays 2245a to 2245d constituting the reflective optical sensor array 2245 are each 19 pieces. It has a light emitting part (E1 to E19), 19 condenser lenses for illumination (LE1 to LE19), and 19 light receiving parts (D1 to D19).

  The image forming apparatus 2000 according to the above-described embodiment scans the photosensitive drums 2030a, 2030b, 2030c, and 2030d and light beams modulated according to image information on the photosensitive drums in the main scanning direction. , An optical scanning device 2010 that forms an electrostatic latent image, four developing rollers 2033a, 2033b, 2033c, and 2033d that attach toner to the electrostatic latent image to generate a toner image, and transfer the toner image from the intermediate transfer belt 2040 A transfer roller 2042 for transferring to paper, a reflection type optical sensor array 2245 for detecting the density of the toner pattern transferred to the intermediate transfer belt 2040, a printer controller 2090 for overall control, and the like are provided. .

  The reflective optical sensor 2245 includes four reflective optical sensor arrays 2245a, 2245b, 2245c, and 2245d corresponding to the respective colors.

  The reflective optical sensor array is arranged in a line along the Y-axis direction, and includes 19 light-emitting portions E1 to E19 that emit detection light beams toward the intermediate transfer belt 2040, and light beams emitted from the light-emitting portions. 19 illuminating condenser lenses LE1 to LE19 for condensing, 19 illuminating condenser lenses LE1 to LE19 for condensing and guiding the light beams reflected by the intermediate transfer belt 2040 or the toner pattern, It has 19 light receiving portions D1 to D19 that receive the light flux reflected by the intermediate transfer belt 2040 or the toner pattern, and a processing device.

  The processing device of each reflective optical sensor array determines whether or not the toner concentration is appropriate based on the detected amount of received light, and if it determines that the toner concentration is not appropriate, develops the corresponding station so as to be appropriate. The processing system is controlled.

  Further, as an example in the above embodiment, the toner patterns TP1 to TP4 may be arranged in a line along the traveling direction of the intermediate transfer belt 2040 as shown in FIG. In this case, the reflective optical sensor 2245 only needs to have one reflective optical sensor array.

  In the above embodiment, the printer control device 2090 may perform at least a part of the processing in the processing device of each detection sensor.

  In the above-described embodiment, the case where the toner pattern TP1 is present at the “position irradiated with the light beams from the light emitting units E9 and E10” is described for performing the toner density detection process. However, the present invention is not limited to this. .

  Of course, the number of light emitting units and light receiving units of the reflective optical sensor array is not limited to 19 as shown in the embodiment, and the same number of light emitting units and light receiving units is also limited thereto. It is not a thing.

  The arrangement direction of the light emitting units and the light receiving units is not limited to “one-line arrangement in the Y-axis direction”, but may be arranged along a direction inclined with respect to the Y-axis direction, and staggered in a plurality of rows along the Y-axis direction. It may be arranged. In short, it suffices if they are arranged at equal intervals in the Y-axis direction.

  In the above embodiment, the case where the toner pattern on the intermediate transfer belt 2040 is detected has been described. However, the present invention is not limited to this, and depending on the form of the image forming apparatus, the toner pattern on the photoconductor may be detected. Also good.

  Although the case of the color printer 2000 including a plurality of photosensitive drums has been described as the image forming apparatus, the present invention is not limited to this, and the present invention is also applied to a printer that includes, for example, one photosensitive drum and forms a monochrome image. it can.

  Further, the present invention can be implemented as an image forming apparatus other than a printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated.

  Above, a reflective optical sensor array in which a plurality of light emitting units / light receiving units / illuminating condensing lenses or an array of a plurality of light emitting units / light receiving units / illuminating condensing lenses / light receiving condensing lenses is arranged An example was explained.

  Of the reflective optical sensor array described in the above embodiment, “part combining one light emitting portion (LED), one light receiving portion (photodiode or phototransistor), and one condenser lens for illumination” Or “A combination of one light emitting part (LED), one light receiving part (photodiode or phototransistor), one illumination condenser lens, and one light receiving condenser lens can be made independent. In this case, they constitute the reflective optical sensor according to claims 1 to 4.

  In the embodiment described above, the light emitting unit Ei, the light receiving unit Di, the illumination condensing lens LEi, or the light emitting unit Ei, the light receiving unit Di, the illumination condensing lens LEi, and the light receiving condensing lens LDi will be described. The contents thus obtained are valid as they are for the reflection type optical sensor.

  When using a conventionally known “single reflection type optical sensor” and considering the positional deviation between the sensor and the toner pattern, the length of the toner pattern in the main direction is set to 15 mm to 25 mm. It is clear that the reflective optical sensor according to claims 1 to 4 can be applied as it is.

  In such a case, the reflective optical sensor according to claims 1 to 4 can be sufficiently reduced in size relative to the conventionally known sensor size. Further, when such a large toner pattern is used, the reflective optical sensors are arranged and integrated at intervals smaller than the size of the two-unit toner pattern, and the light emitting portions of the respective reflective optical sensors are blinked independently. When the toner density detection and the toner pattern position detection are performed by blinking the two light emitting units at the same time, the tolerance for the deviation of the toner pattern in the main direction can be increased, and it is necessary accordingly. The toner pattern size can be reduced.

  Further, in the reflection type optical sensor array in which three or more units of reflection type optical sensors are arranged, the same toner density detection and toner pattern position detection as in the above-described decimal form can be performed.

  When the reflective optical sensor array described in the above-described embodiment is used, the size (area) of the toner pattern can be “one hundredth or less of the conventional”.

  The toner that forms the toner pattern is “a non-contributing toner that does not contribute to the configuration of the image to be formed”. However, as described above, the size of the toner pattern can be significantly reduced as compared with the conventional case. Can be effectively reduced, and the replacement cycle of the toner cartridge can be lengthened.

LEi light emitter
Di light receiver
LEi Condensing lens for illumination
2040 Intermediate transfer belt (supporting medium)

JP-A-1-35466 JP 2004-21164 A JP 2002-72612 A JP 2004-309292 A JP 2004-309293 A Japanese Patent No. 4154272

Claims (10)

A reflective optical sensor for detecting at least one of a position and a toner density of a toner pattern having a fixed shape formed on the surface of a carrier medium carrying a toner pattern,
A semiconductor light emitting device and a photodiode are arranged and integrated such that the light emitting axis of the semiconductor light emitting device and the light receiving axis of the photodiode are parallel to each other so that the light emitting axis and the light receiving axis are close to each other. A body-type light-emitting / receiving element;
A condensing lens for illumination that exerts a converging effect on the light beam emitted from the semiconductor light emitting element and applied to the surface of the carrier medium;
The illumination condensing lens has its optical axis parallel to the light emission axis and is shifted to the photodiode side by a shift amount: Δ,
A light beam radiated from the semiconductor light emitting element onto the light emitting axis is refracted by the illumination condenser lens and obliquely incident on the surface of the carrier medium orthogonal to the light emitting axis at an incident angle of Θ, and the surface of the carrier medium. The positional relationship between the semiconductor light emitting element, the photodiode, and the illumination condenser lens is adjusted so that the light is regularly reflected by the light incident on the center of the light receiving portion of the photodiode.
The incident optical angle Θ is set to 10 degrees or less. The reflective optical sensor according to claim 1,
A light receiving condensing lens that condenses the reflected light from the carrier medium toward the photodiode, and the optical axis of the light receiving condensing lens is parallel to the optical axis of the illumination condensing lens; A reflective optical sensor characterized in that it is shifted to the illumination condenser lens side. The reflective optical sensor according to claim 2, wherein
A reflective optical sensor characterized in that an illumination condenser lens and a light-receiving condenser lens have an integral structure. The reflective optical sensor according to any one of claims 1 to 3,
Reflective optics characterized in that a light beam emitted from a semiconductor light emitting element on a light emitting axis and refracted by an illuminating condenser lens is incident obliquely on the surface of the carrier medium: incident angle: Θ is set to 5 degrees or less Sensor. The reflection type optical sensor according to any one of claims 1 to 4, wherein two units or more of the reflection type optical sensor are orthogonal to the light emitting axis of the semiconductor light emitting element and the light receiving axis of the photodiode, In the direction of a straight line passing between the light emitting axis and the light receiving axis, the array is arranged at a pitch smaller than the size of the toner pattern in this direction
At least the semiconductor light emitting element and the photodiode are integrated as a whole,
A reflective optical sensor array, wherein the semiconductor light emitting element can be blinked independently in each reflective optical sensor unit. The reflective optical sensor array according to claim 5, wherein
2. A reflection type optical sensor array, in which two or more units of reflection type optical sensors arranged in an array are integrated with a condenser lens for illumination. The reflective optical sensor according to claim 6, wherein
A reflective optical sensor array, wherein the arrayed reflective optical sensor has a light receiving condensing lens, and the arrayed light receiving condensing lens is integrated with the illumination condensing lens. In an image forming apparatus that forms an image with toner,
A toner image forming means for forming a toner pattern and a toner image for image formation on a carrier medium carrying the toner pattern;
A reflective optical sensor for detecting at least one of the position of the toner pattern formed on the carrier medium and the toner density;
The image forming apparatus according to claim 1, wherein the reflective optical sensor is any one of claims 1 to 4. In an image forming apparatus that forms an image with toner,
A toner image forming means for forming a toner pattern and a toner image for image formation on a carrier medium carrying the toner pattern;
A reflective optical sensor array for detecting at least one of the position of the toner pattern formed on the carrier medium and the toner density, and
The image forming apparatus according to any one of claims 5 to 7, wherein the reflective optical sensor array is one. The image forming apparatus according to claim 8 or 9,
An image forming apparatus, wherein the formed image is a multicolor image or a color image using a plurality of types of toners having different colors.

Images