JP2007139591A - Spectrometry device, and image forming apparatus having it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spectrometry device capable of measuring a spectral characteristic of a measuring object highly accurately with a simple constitution. <P>SOLUTION: This spectrometry device has a casing 101 having a rectangular opening part 102, a polymer multilayered film 103 wherein a light flux passing the rectangular opening part of the casing has a transmissivity characteristic differentiated by the wavelength corresponding to an incident angle arranged curvedly so that the incident angle is different in the longitudinal direction of the opening part, a photoelectric conversion part 105 wherein a plurality of light receiving elements are arrayed linearly in the longitudinal direction of the opening part, and an operation means 106 for operating information on the wavelength of the entering light flux by using a signal outputted from the photoelectric conversion part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectroscopic measuring apparatus for identifying spectral characteristics of a subject, for example, color information, and in particular for color measurement of toner, printing medium, etc. in an electrophotographic image forming apparatus such as a laser beam printer (LBP), a digital copying machine, etc. Is preferred.

  In an image forming apparatus that forms a color image by an electrophotographic method, a color shift may occur in image information obtained by toner color mixing. Various image forming apparatuses having means for solving such problems have been proposed (see Patent Document 1).

  In Patent Document 1, the amount of spectral reflection of a light beam reflected from a toner image formed on a photoreceptor is measured using two different spectral filters. And the method of correct | amending the color information of an image signal using the measurement result is disclosed.

  FIG. 6 is a main part configuration diagram showing the configuration of the reflected light amount detector disclosed in Patent Document 1.

In the figure, a light source 64 irradiates the surface of the photoreceptor 61 with light, and includes a halogen lamp or a light emitting diode. The light receiving element 65 detects light from the light source 64 reflected by the photoconductor 61 and outputs an electric signal having a magnitude corresponding to the light intensity detected at that time.
As the light receiving element 65, a photoelectric conversion type light receiving element is used.

  The optical spectral filter 66 is disposed in close contact with or close to the light receiving surface of the light receiving element 65 in order to spectrally absorb the reflected light from the photosensitive member 61. As the spectral filter 66, at least two types of filters having different spectral transmission spectra are prepared, and one of them is selected. As a selection method, one filter is automatically replaced by a known method such as a slide type or a rotary type.

  In the reflected light quantity detector described above, the reflected light quantity of different spectral components is detected by using one set of light source and light receiving element and replacing one of the plurality of spectral filters. The embodiment of Patent Document 1 is not limited to this, and at least two or more combinations of light sources and light receiving elements are prepared. Then, by arranging different spectral filters according to the respective combinations, the amount of reflected light of the light beam reflected by the photoreceptor 61 is detected for each different spectral component.

  On the other hand, in recent years, image quality of image forming apparatuses has been rapidly improved, and these image quality improvements have been frequently used for color image output means.

  In the image forming means for forming a color image, toners of four colors of cyan (C), magenta (M), yellow (Y), and black (Bk) are used. An image is formed by giving gradation to each toner, and the formed image can express almost all colors in the visible range.

  Therefore, an apparatus that detects the spectral reflectance of toner using two types of filters cannot sufficiently evaluate color information. As the filter, at least three kinds of filters corresponding to the number of primary colors are required.

  Further, the color of the image formed by the toner varies depending on the material and the manufacturing method, and the subtle color tone of the print medium also changes. For this reason, in order to perform advanced color correction in image processing, it is necessary to measure the color of the toner with a spectrum (continuous spectrum) having a number of colors far exceeding the number of primary colors 3.

As a method for performing continuous spectroscopy, a spectroscopy using a diffraction grating or a prism has been conventionally known (see Non-Patent Document 1).
JP 09-160343 A Tetsuo Sueda, “How to Use Optical Components and Points to Consider,” Optronics, February 28, 1985, p. 86

  In Japanese Patent Laid-Open No. 2004-260260, a method of performing spectroscopic analysis by installing a plurality of reflected light amount detectors around the photosensitive member or by using a large number of light sources and spectral filters is also conceivable. However, these methods are not practical because the entire apparatus becomes larger and more complicated.

  In Non-Patent Document 1, continuous spectroscopy can be performed, but there are some problems in using this in an image forming apparatus. For example, an elongated slit is required. When this is used, since the amount of light obtained is small, it is necessary to take a sufficient amount of time to measure with sufficient signal accuracy. Moreover, there are many components and the whole apparatus becomes large. Further, there is a problem that the positional accuracy of each optical element occurs due to the expansion of each member due to temperature or the like, and the measurement accuracy deteriorates.

  2. Description of the Related Art Conventionally, image forming apparatuses are always required to be downsized and simplified along with high image quality. Further, since the heater for fixing the toner is used, the change in the internal temperature is large. Therefore, it has been extremely difficult to introduce a conventional continuous spectral type colorimetric apparatus into an image forming apparatus.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a spectroscopic measurement apparatus that can measure the spectral characteristics of an object to be measured with a simple configuration with high accuracy.

  Another object of the present invention is to provide a spectroscopic measurement apparatus suitable for colorimetry of toner and print media in an image forming apparatus and an image forming apparatus having the same.

The spectroscopic measurement device of the invention of claim 1
A transmittance having a housing having a rectangular opening and a light beam that has passed through the rectangular opening of the housing is curved according to an incident angle in which the incident angle is different in the longitudinal direction of the opening. Polymer multilayer film having different characteristics depending on wavelength, a photoelectric conversion unit in which a plurality of light receiving elements are linearly arranged in the longitudinal direction of the opening, and a light beam incident using a signal output from the photoelectric conversion unit And a calculation means for calculating information relating to the wavelength.

The invention of claim 2 is the invention of claim 1,
It is characterized by having a plurality of slit members that subdivide the longitudinal direction of the opening in accordance with the arrangement pitch of the plurality of light receiving elements.

The invention of claim 3 is the invention of claim 1 or 2, wherein
When the length in the longitudinal direction of the opening is A, and the optical path length from the incident-side surface of the opening to the surface of the photoelectric converter is B, A / B ≦ 0.8
It is characterized by satisfying the following conditions.

The invention of claim 4 is the invention of claim 2,
When the interval in the longitudinal direction of the plurality of slit members is Aa and the optical path length from the light incident side end of the slit members to the surface of the photoelectric conversion unit is Bb, Aa / Bb ≦ 0.8
It is characterized by satisfying the following conditions.

The spectroscopic measurement device of the invention of claim 5
An opening member having a rectangular opening, an optical element having a spectral characteristic that varies depending on the incident angle of the light beam, the optical element is opposed to the opening, and the light beam incident from the opening is A photoelectric conversion unit in which a plurality of light receiving elements are arranged in one direction, and is arranged so as to be curved along the longitudinal direction of the opening so that the incident angle varies along the longitudinal direction of the opening, and the photoelectric conversion unit Are arranged along the longitudinal direction of the opening on the side opposite to the opening member with respect to the optical element in order to detect the light flux through each area of the optical element for each area, And calculating means for calculating the spectral characteristic of the light beam incident from the opening using the signal detected by the photoelectric conversion unit.

The invention of claim 6 is the invention of claim 5,
The optical element is a polymer multilayer film.

The invention of claim 7 is the invention of claim 5 or 6,
It has a plurality of slit members that subdivide the longitudinal direction of the opening in accordance with the arrangement pitch of the light receiving elements of the photoelectric conversion unit.

The spectroscopic measurement system of the invention of claim 8
8. A light source means for radiating a light beam in a predetermined direction, and a light beam from the light source means and detected via the object to be measured by the spectroscopic measurement device according to any one of claims 1 to 7. Yes.

The image forming apparatus of the invention of claim 9
The spectroscopic measurement system according to claim 8 and a photoconductor for measuring the spectroscopic characteristics of a toner image formed on the surface of the spectroscopic measurement system.

  According to the present invention, it is possible to achieve a spectroscopic measurement apparatus that can measure a measured object with high accuracy by continuous spectroscopy and an image forming apparatus having the spectroscopic measurement apparatus.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view of the essential portions of Embodiment 1 of the spectrometer of the present invention.

  In the figure, reference numeral 100 denotes a spectrometer. Reference numeral 101 denotes a light shielding case (housing) as an opening member. Reference numeral 102 denotes a rectangular opening, which is provided on the light incident side (drawing, upper part) of the light shielding case 101.

  Reference numeral 103 denotes an optical element as a spectroscopic means, which is composed of a polymer multilayer film, and has a characteristic that the transmittance characteristic varies depending on the wavelength according to the incident angle of the light beam (light ray) as shown in FIG. . The polymer multilayer film 103 in this embodiment is curved so that the incident angle of the light beam from the opening 102 is different in the longitudinal direction of the opening 102.

  FIG. 2 is a schematic view of the spectral transmittance of the polymer multilayer film of this example. As shown in FIG. 2, the spectral transmittance of the polymer multilayer film of this example differs depending on the incident angle. As the incident angle increases, the transmittance of the light beam on the long wavelength side decreases.

  In this embodiment, the polymer multilayer film 103 is curved so that the incident angle of the light beam is 0 ° to 72 ° with respect to the light beam incident from the entire opening 102.

  The polymer multilayer film 103 can vary the transmittance characteristics of the light flux depending on the wavelength by setting the film thickness, the number of layers, and the material. As a specific example, for example, a multilayer optical body disclosed in JP-T-2003-515754 is cited. The polymer multilayer film in the publication has a plurality of first optical layers including polyesters having a glass transition temperature of about 90 ° C. or less, in which each optical layer is oriented and which has a terephthalate comonomer unit and an ethylene glycol comonomer unit. Each optical layer includes an optical body including a polymer composition and includes a plurality of first optical layers and a plurality of second optical layers arranged in a repeating order, and at least one of light over at least one wavelength region. Configured and arranged to reflect the part.

  Reference numeral 104 denotes a substrate, which fixes a photoelectric conversion unit 105 described later. The photoelectric conversion unit 105 is provided at the bottom (drawing, lower part) in the light shielding case 101, and a plurality (five in the present embodiment) of photoelectric conversion elements (pixels, light receiving elements) 105a with respect to the longitudinal direction of the opening 102. ~ 105e are arranged in a straight line. The photoelectric conversion unit 105 receives the light beam transmitted through the polymer multilayer film 103.

  Reference numeral 106 denotes a processing device (calculation means), which obtains information (color information) about the wavelength of the incident light beam by processing the electrical signal output from the photoelectric conversion unit 105.

  In this embodiment, the light beam from the object to be measured (not shown) that has passed through the rectangular opening 102 passes through the polymer multilayer film 103 held by the indicator (not shown) fixed to the light shielding case 101. Then, the light enters the photoelectric conversion unit 105 fixed to the substrate 104.

  The electrical signal output from the photoelectric conversion unit 105 is processed by the processing device 106 to obtain information on the wavelength of the light beam.

  As described above, the polymer multilayer film 103 is curved and fixed so that incident light beams have different incident angles in the longitudinal direction (left-right direction in the figure) of the opening 102.

  That is, the polymer multilayer filter has different spectral characteristics of transmitted light according to the incident angle of the light flux as shown in FIG. For this reason, the color information of the light beam incident on each of the light receiving elements 105a to 105e is split into color components as illustrated in FIG.

  By processing these color information by the processing device 106, as shown in FIG. 1, output signals a ′ (blue), b ′ (green), c ′ (yellow), d ′ ( Orange) and e ′ (red) can be obtained.

As processing contents, for example, to obtain color information of the output signal e ′ (red), an input signal 105e (blue + green + yellow + orange + red) and an input signal 105d (blue + green + yellow + orange) are used. And
e '= 105e-105d
What is necessary is just to obtain | require the relative difference of a signal output like this.

  In FIG. 1, the photoelectric conversion unit 105 includes five light receiving elements 105a to 105e. However, if necessary, the number of light receiving elements can be easily increased or decreased while the polymer multilayer film 103 remains the same. .

  For example, if the number of light receiving elements is increased, it is possible to evaluate by subdividing the wavelength characteristics (spectral characteristics). Conversely, if the number is reduced, the photoelectric conversion unit 105 can be further simplified.

In this embodiment, when the length in the longitudinal direction of the opening 102 is A and the optical path length from the incident-side surface of the opening 102 to the surface of the photoelectric conversion unit 105 is B, A / B ≦ 0. 8 (1)
Satisfy the following conditions.

  Conditional expression (1) relates to the ratio between the longitudinal length A of the opening 102 and the optical path length B from the incident-side surface of the opening 102 to the surface of the photoelectric conversion unit 105. If the conditional expression (1) is deviated from, for example, about 1.0, light enters the light receiving element array at an incident angle of about 45 ° at the maximum, and a large amount of light around the object to be measured is received. As a result, accurate spectral accuracy cannot be maintained, which is not good.

In this example,
A = 5mm, B = 9mm
It is said. Therefore, the left side of conditional expression (1) is
A / B = 0.55
This satisfies the conditional expression (1). Thereby, in this embodiment, sufficient spectral performance can be obtained.

  More preferably, the numerical range of conditional expression (1) is set as follows.

0.1 ≦ A / B ≦ 0.6 (1a)
If the upper limit of conditional expression (1a) is not reached, the angle of incidence is limited to about 30 ° at the maximum, so that the spectral accuracy becomes higher and it can be applied to devices that require high accuracy. If the lower limit value of conditional expression (1a) is not reached, the spectral accuracy is high, but the amount of light incident on the light receiving element decreases. Therefore, in some cases, the exposure time must be lengthened, which is not preferable.

  As described above, in this embodiment, the polymer multilayer film 103 is curved in the longitudinal direction of the opening 102 so that the incident light flux has a different incident angle, thereby having an extremely small number of parts and a simple structure. It is possible to perform continuous spectroscopy (color number spectroscopy).

  Further, in this embodiment, information on the wavelength of the incident light beam can be obtained by processing the electrical signals output from the plurality of different light receiving elements 105a to 105e as described above by the processing device 106. This makes it possible to easily obtain a light amount ratio of only a necessary wavelength band in the same manner as in a conventional diffraction grating type spectrometer.

  FIG. 3 is a schematic view of the essential portions of Embodiment 2 of the spectrometer of the present invention. In the figure, the same elements as those shown in FIG.

  This embodiment differs from the first embodiment described above in that slit members 307 are provided in accordance with the arrangement pitch of the plurality of light receiving elements 105a to 105e so that the opening 102 is subdivided in the longitudinal direction. Other configurations and optical functions are the same as those in the first embodiment, and the same effects are obtained.

  That is, in FIG. 3, reference numeral 307 denotes a slit member, which is provided in accordance with the arrangement pitch of the plurality of light receiving elements 105a to 105e so as to subdivide the opening 102 in the longitudinal direction.

  In the present embodiment, the slit member 307 configures the position of the polymer multilayer filter 103 through which the light beam passes and the position of the light receiving elements 105a to 105e in a one-to-one correspondence. As a result, color mixing with adjacent light receiving elements can be reduced, and spectral performance can be further improved.

In this embodiment, when the width in the longitudinal direction between the slit members 307 is Aa and the optical path length from the incident side end 307a of the slit member 307 to the surface of the photoelectric conversion unit 105 is Bb, Aa / Bb ≦ 0. 8 (2)
Satisfy the following conditions.

  Conditional expression (2) relates to the ratio between the width Aa between the slit members 307 and the optical path length Bb from the end 307a on the incident side of the slit member 307 to the surface of the photoelectric conversion unit 105. When deviating from conditional expression (2), for example, about 1.0, light enters the light receiving element array at an incident angle of about 45 ° at the maximum, and a large amount of light around the object to be measured is received, resulting in accurate spectral accuracy. It's not good because it can't be maintained.

In this example,
Aa = 1mm, Bb = 7mm
Therefore, Aa / Bb = 0.14
This satisfies the conditional expression (2). Thereby, in this embodiment, sufficient spectral performance can be obtained.

  More preferably, the numerical range of conditional expression (2) is set as follows.

0.1 ≦ Aa / Bb ≦ 0.6 (2a)
If the upper limit of conditional expression (2a) is not reached, the angle of incidence is limited to about 30 ° at the maximum, so that the spectral accuracy becomes higher and it can be applied to devices that require high accuracy. If the lower limit value of conditional expression (2a) is not reached, the spectral accuracy is high, but the amount of light incident on the light receiving element decreases. Therefore, in some cases, the exposure time must be lengthened, which is not preferable.

  In this embodiment, a measurement object to be spectrally measured is placed in front of the opening 102, but it is desirable that the spectral accuracy is not deteriorated by light around the measurement object. Therefore, in this embodiment, by providing the slit member 307 so as to subdivide the rectangular opening 102 in the longitudinal direction as described above, it becomes possible to further limit the angle of the light beam incident on each of the light receiving elements 105a to 105e. This improves the spectral accuracy.

  FIG. 4 is a schematic view of the essential portions of Embodiment 3 of the spectrometer of the present invention. In the figure, the same elements as those shown in FIG.

  This embodiment differs from the first embodiment described above in that folding mirrors 408 and 409 are provided on the front and rear sides of the polymer multilayer film 103, and the optical path is bent. Other configurations and optical functions are the same as those in the first embodiment, and the same effects are obtained.

  That is, in this embodiment, the light flux from the object to be measured (not shown) that has passed through the rectangular opening 102 provided in the light shielding case 101 is the folding mirror 408 held on the light shielding case 101 by the support portion (not shown). The optical path can be bent 90 degrees. The light beam bent by the folding mirror 408 passes through the polymer multilayer film 103 that is also held by a support portion (not shown). The light beam that has passed through the polymer multilayer film 103 is incident on the photoelectric conversion unit 105 fixed to the substrate 104 after the optical path is bent again by 90 ° by a folding mirror 409 that is also held by a support unit (not shown). .

  The electrical signal output from the photoelectric conversion unit 105 is processed by the processing device 106 to obtain information on the wavelength of the incident light beam.

  The polymer multilayer film 103 is curved and fixed so that incident light beams have different incident angles in the longitudinal direction (vertical direction in the figure) of the opening 102 as viewed optically.

  That is, since the polymer multilayer filter 103 has different spectral characteristics of transmitted light according to the incident angle of the light beam as shown in FIG. 2, the color information incident on the light receiving elements 105a to 105e is the color illustrated in FIG. Spectroscopy into components.

  Such color information can be obtained by processing by the processing device 106 in the same manner as in the first embodiment.

In this embodiment, the length A in the longitudinal direction of the opening 102 and the optical path length B from the incident-side surface of the opening 102 to the surface of the photoelectric conversion unit 105 are A = 5 mm and B = 28 mm, respectively.
Therefore A / B = 0.18
This satisfies the conditional expression (1). Thus, in this embodiment, sufficient spectral performance can be obtained without using the slit member shown in FIG.

  In each of the embodiments described above, any member that can be bent as long as the spectral characteristics differ depending on the incident angle of the light beam in addition to the polymer multilayer film as the optical element may be used. For example, a dielectric multilayer film may be used. Filters having different spectral characteristics depending on the incident angle by forming a dielectric multilayer film on a glass substrate are well known. A member that can bend this substrate. For example, it may be manufactured by replacing with a polycarbonate resin substrate.

  Instead of detecting the amount of light transmitted through the optical element by the photoelectric conversion unit, the amount of reflected light may be detected.

  FIG. 5 is a schematic diagram of a main part of an image forming apparatus using the spectroscopic measurement system of the present invention.

  In the figure, 1 is a photosensitive member, 2 is a static eliminator, 3 is a first electrostatic latent image forming unit, 4 is a first developing device, 4-1 is a developing roll, and 5 is a second electrostatic latent image. The forming unit 6 is a second developing device. 7 is a transfer pre-processing device, 8 is a transfer device, 9 is a recording paper, and 10 is a cleaning device.

  Although not shown, the electrophotographic image forming apparatus of the present invention includes an optical scanning device having light source means, a polygon mirror, and an fθ lens in order to form an image on a photosensitive member.

  A spectroscopic measurement system 11 includes the spectroscopic measurement apparatus according to any one of the first to third embodiments and a light source unit. The spectroscopic measurement system 11 is disposed in the vicinity of the surface of the photoconductor 1 at approximately the center in the axial direction of the photoconductor 1.

  In this embodiment, the toner image formed on the surface of the photosensitive member 1 is irradiated with the light beam from the light source means, and the spectral reflected light amount from the light beam is detected by the spectroscopic measurement device.

  As described above, each of the first to third embodiments described above realizes a spectroscopic measurement apparatus that can be downsized with a simple configuration with a small number of parts and that can perform continuous spectroscopy.

  The selection of the spectral wavelength is determined by the incident angle of the light flux on the polymer multilayer filter and is insensitive to the same type of apparatus, so that the performance change due to expansion or the like is small even in an environment where the temperature change is large. Therefore, the image forming apparatus can be incorporated.

  The present invention is not limited to an image forming apparatus, and can be used as a spectroscopic measurement apparatus, for example, a white balance sensor such as a digital camera, and other spectroscopic measurement apparatuses.

Schematic diagram of essential parts of Embodiment 1 of the present invention Angle characteristic diagram of spectral transmittance of polymer multilayer filter of Example 1 of the present invention Schematic diagram of essential parts of Embodiment 2 of the present invention Schematic diagram of essential parts of Embodiment 3 of the present invention 1 is a schematic view of a main part of an image forming apparatus according to an embodiment of the present invention. Schematic diagram of the main parts of a conventional spectrometer

Explanation of symbols

101 Case (shading case)
DESCRIPTION OF SYMBOLS 102 Opening part 103 Polymer multilayer film 104 Board | substrate 105 Photoelectric conversion part 106 Calculation means (processing apparatus)
307 Slit member 408, 409 Folding mirror

Claims (9)

  A transmittance having a housing having a rectangular opening and a light beam that has passed through the rectangular opening of the housing is curved according to an incident angle in which the incident angle is different in the longitudinal direction of the opening. Polymer multilayer film having different characteristics depending on wavelength, a photoelectric conversion unit in which a plurality of light receiving elements are linearly arranged in the longitudinal direction of the opening, and a light beam incident using a signal output from the photoelectric conversion unit A spectroscopic measurement apparatus comprising: an arithmetic means for calculating information relating to the wavelength.   The spectroscopic measurement apparatus according to claim 1, further comprising a plurality of slit members that subdivide the longitudinal direction of the opening in accordance with an arrangement pitch of the plurality of light receiving elements. When the length in the longitudinal direction of the opening is A, and the optical path length from the incident-side surface of the opening to the surface of the photoelectric converter is B, A / B ≦ 0.8
The spectroscopic measurement apparatus according to claim 1, wherein the following condition is satisfied. When the interval in the longitudinal direction of the plurality of slit members is Aa and the optical path length from the light incident side end of the slit member to the surface of the photoelectric conversion unit is Bb, Aa / Bb ≦ 0.8
The spectroscopic measurement apparatus according to claim 2, wherein the following condition is satisfied.   An opening member having a rectangular opening, an optical element having a spectral characteristic that varies depending on the incident angle of the light beam, the optical element is opposed to the opening, and the light beam incident from the opening is A photoelectric conversion unit in which a plurality of light receiving elements are arranged in one direction, and is arranged so as to be curved along the longitudinal direction of the opening so that the incident angle varies along the longitudinal direction of the opening, and the photoelectric conversion unit Are arranged along the longitudinal direction of the opening on the side opposite to the opening member with respect to the optical element in order to detect the light flux through each area of the optical element for each area, A spectroscopic measurement apparatus comprising: a calculating unit that calculates and obtains spectral characteristics of a light beam incident from the opening using a signal detected by a photoelectric conversion unit.   The spectroscopic measurement apparatus according to claim 5, wherein the optical element is a polymer multilayer film.   7. The spectroscopic measurement apparatus according to claim 5, further comprising a plurality of slit members that subdivide the longitudinal direction of the opening in accordance with the arrangement pitch of the light receiving elements of the photoelectric conversion unit.   8. A light source means for radiating a light beam in a predetermined direction, and a light beam from the light source means, the light beam passing through the object to be measured, detected by the spectroscopic measurement device according to any one of claims 1 to 7. Spectral measurement system.   An image forming apparatus comprising: the spectroscopic measurement system according to claim 8; and a photoconductor for measuring spectral characteristics of a toner image formed on a surface of the spectroscopic measurement system.