JP2019060781A - Spectrophotometric device and image forming apparatus - Google Patents

Abstract

To make it possible to reduce the size of a spectrophotometric device without deteriorating the accuracy in color measurement.SOLUTION: A spectrophotometric unit 400 is urged against a holding member body 501 with urging means 503 to be held in the holding member body 501, and the holding member body 501 is urged with the spectrophotometric unit 400 therebetween to move the spectrophotometric unit 400 to a position for color measurement.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a spectral colorimetry device using an illumination device and an image forming apparatus provided with the same.

  In an image forming apparatus in which a color image is formed by electrophotography, deviation in color tone may occur due to instability in the color mixing of toner and the like and a problem of reproducibility. This is not limited to the electrophotographic method, and has the same problem in general in the image forming apparatus for forming a color image such as an inkjet method. In the electrophotographic system, the drum sensitivity, the charge capacity of the toner, and the transfer efficiency to paper differ depending on the use environment and the degree of use, and the color mixture ratio tends to deviate from the predetermined value to the color tone. Furthermore, in the printing industry, it is necessary to realize higher tone reproduction.

  In order to solve such problems, a compact spectral colorimetry apparatus suitable for an image forming apparatus has been proposed, and in Patent Document 1, a compact spectral colorimetry suitable for a color image forming apparatus as described below An apparatus has been proposed. The spectral colorimetry apparatus includes a light source, an illumination optical system for illuminating an object disposed on a surface to be examined, a light guiding optical system for guiding a light flux from the object to the spectroscopic optical system, and a light flux And a spectral optical system for obtaining a spectral intensity distribution, and a light receiving element for receiving the light thus separated. In the configuration of Patent Document 1, the light guide 130 of the illumination optical system and the light guide element 140 of the light guide optical system are separately provided, but in recent years, the cost reduction due to the reduction in the number of parts and the simplification of the assembly process A configuration using a light guide in which an illumination optical system and a light guide optical system are integrated is also proposed.

Unexamined-Japanese-Patent No. 2013-140188

However, there are the following unsolved problems in the conventional spectrophotometric apparatus.
FIG. 9 shows a fixing method of the conventional spectral colorimetry apparatus 100. As shown in FIG. The conventional spectral colorimetry apparatus 100 is fixed to a holding member (not shown) of the image forming apparatus by fixing means (not shown) in the fixing unit 1020. The fixing unit 1020 needs to be disposed outside the space A which is responsible for spectral colorimetry in the XY plane, so the size of the apparatus is increased accordingly. Next, for example, when a screw is used as the fixing means, the spectral colorimetry device 100 is deformed by the frictional force at the time of screwing received by the fixing portion 1020, the positional accuracy of each optical element is deteriorated, and the colorimetric accuracy is deteriorated. I will. In order to maintain the measurement accuracy, it is necessary to secure a large separation distance from the space (the shaded area) A for carrying out the spectral measurement to the fixed portion 1020, and the apparatus is further enlarged.

  An object of the present invention is, in view of the problems described above, to propose a configuration that enables downsizing of a spectrometric colorimetry device without deteriorating the colorimetry accuracy.

In order to achieve the above object, the spectral colorimetry device of the present invention is
A light source; an illumination optical system for guiding a light flux from the light source onto a test surface; a light guide optical system for guiding reflected light from the test surface; and an incident light flux from the light guide optical system A spectral colorimetry unit having a spectral optical system for spectral separation, and a light receiving element for receiving and detecting a light flux dispersed by the spectral optical system;
A holding member for holding the spectral colorimetry unit;
A displacement mechanism for moving the spectral colorimetry unit to a first position during color measurement and a second position during non-color measurement;
Biasing means for holding the spectral colorimetry unit on the holding member by urging the spectral colorimetry unit with respect to the holding member in a direction to move from the second position to the first position; It is characterized by having.

  As described above, according to the present invention, it is possible to miniaturize the spectral colorimetry device without deteriorating the colorimetry accuracy.

The perspective view of the spectrocolorimetry apparatus of Example 1 (A) is a YZ cross-sectional view of the spectral colorimetry device 400, (b) is an XZ cross-sectional view of the light guide 403 Explanatory drawing of the fixing method of the spectrocolorimetry apparatus 400 of Example 1. Correlation diagram of light quantity of detected luminous flux and relative distance in Z direction XZ sectional view of contact / separation mechanism at the time of contact ((a)), separation ((b)) The figure which shows the fixing method of the spectral-coloring apparatus of Example 1 and a comparative example. A color image forming apparatus to which the spectral colorimetry device according to the first embodiment is applied Another color image forming apparatus to which the spectral measurement device of the first embodiment is applied The figure which shows the fixing method of the spectrocolorimetry apparatus of patent document 1

  Hereinafter, with reference to the drawings, modes for carrying out the present invention will be exemplarily described in detail based on examples. However, the dimensions, materials, shapes, etc. of the components described in this embodiment should be changed as appropriate depending on the configuration of the apparatus to which the invention is applied and various conditions. That is, the scope of the present invention is not intended to be limited to the following embodiments.

  FIG. 7 is a view showing a color image forming apparatus according to Embodiment 1 of the present invention. In the figure, reference numeral 20 denotes a spectrocolorimetry apparatus having a configuration to be described later. Reference numerals 1C, 1M, 1Y and 1BK denote photosensitive drums as image bearing members arranged at equal intervals.

  The image forming means in the present embodiment will be described. Respective light beams (laser beams) LC, LM, LY, LBK light-modulated respectively based on image information are emitted from the scanning optical device 300, and illuminate the surfaces of the corresponding photosensitive drums 1C, 1M, 1Y, 1BK. Form a latent image. The latent images are formed on the surfaces of the photosensitive drums 1C, 1M, 1Y, 1BK uniformly charged by the primary chargers 2C, 2M, 2Y, 2BK, respectively. The latent images are visualized as cyan, magenta, yellow and black images by the developing devices 4C, 4M, 4Y and 4BK, respectively, and the transfer rollers 5C, 5M and 5Y are transferred onto the recording medium P transported on the transfer belt 10. , And 5BK to form a color image by electrostatic transfer. Here, examples of the recording medium include paper. After that, the residual toner remaining on the photosensitive drums 1C, 1M, 1Y and 1BK is removed by the cleaners 6C, 6M, 6Y and 6BK, and the primary chargers 2C and 2M are again formed to form the next color image. , 2Y, 2BK uniformly.

The recording media P are stacked on a sheet feeding tray 7, sequentially fed sheet by sheet by the sheet feeding roller 8, and sent out onto the transfer belt 10 in synchronization with the image writing timing by the registration roller 9. A cyan image, a magenta image, a yellow image, and a black image formed on the photosensitive drums 1C, 1M, 1Y and 1BK while being conveyed on the transfer belt 10 with high accuracy on the recording medium P in order The toner image is transferred to form a color image (toner image). The driving roller 11 feeds the transfer belt with high accuracy, and is connected to a driving motor (not shown) with small rotation unevenness. The color image formed on the recording medium P is pressed, heated and fixed by the fixing unit 12, and is then conveyed by the paper discharge roller 13 or the like and output to the outside of the apparatus. In the present embodiment, the image forming unit includes the transfer belt 10 such as the photosensitive drum 1C, the primary charger 2C, the developing device 4C, the transfer roller 5C, and the like.

  The spectral colorimetry device 20 is installed on the paper conveyance path downstream (immediately after) of the fixing unit 12 and illuminates the illumination light on the image surface on which the color patch formed on the surface of the recording medium P is fixed. Are arranged to be irradiated. The spectral colorimetry apparatus 20 is integrally held movably by the holding member 501, and is separated and disposed at a position that does not interfere with paper conveyance during normal image output where colorimetry is not performed. It is configured to be close to the color patch only to the desired position. The recording medium P on which the color patch has been image-formed through the fixing unit is detected and measured by the spectrometric device 20 according to the color patch conveyed on the paper, for each color patch. Here, the color patch on the paper surface after image fixing is measured in order to perform color matching in consideration of the change in chromaticity due to the paper type, fixing, and the like.

Next, the detection result read by the spectral colorimetry device 20 is transferred to a printer controller (not shown), and the printer controller determines whether the color reproducibility of the output color patch is properly achieved. If the color difference of the output single color or mixed color patch is within a predetermined range at the chromaticity instructed by the print controller, the color calibration is ended. If the color difference is out of the predetermined range, the printer controller can perform color calibration based on the color difference information until the color difference falls within the predetermined color difference.
As described above, by mounting the spectral colorimetry device 400 in the color image forming apparatus, the chromaticity difference of the color image formed on the paper surface depending on the machine difference of the image forming apparatus, the paper type, the use environment, the use frequency Can be corrected to absolute chromaticity under all conditions. For this reason, more accurate color calibration can be realized by reliably reproducing stable chromaticity.

  A spectral colorimetry unit 400 constituting the spectral colorimetry device 20 of the present invention is shown in FIG. Fig.1 (a) is a perspective view, FIG.1 (b) has shown the rear view. The spectral colorimetry unit 400 holds, on a housing 401, a light guide 403 in which an illumination optical system and a light guide optical system are integrated, and a spectral optical system 206. The light source 202 and the light receiving element 207 are mounted on the electric substrate 411, and the electric substrate 411 is fixed to the housing 401 by screws 415 and 416. The slit 405 is integrally molded in the resin housing 401. The housing 401 is provided with a Z seat 401a, a pressed portion 401b, an X seat 401c, and a Y seat 401d. G1 indicates the center of gravity of the spectral colorimetry unit 400. The Z bearing surface 401a is provided so that the center of gravity G1 is located inside a triangle connecting the seating surfaces in the XY plane. The pressed portion 401b is provided at substantially the same position as the center of gravity G1 in the XY plane. That is, the center of gravity G1 of the spectral colorimetry unit 400 is provided at a position overlapping the pressed portion 401b when viewed in the XY plane (a plane perpendicular to the direction of the urging force by the urging means 503 described later). A cover 409 provided with a PET cover sheet 408 is attached to the opening side of the housing 401. A part of the cover 409 is provided with an opening window in order to secure an optical path of irradiation light from the light guide 403 to a color patch (not shown) and reflected light guided from the color patch to the light guide 403. In the cover 409, a cover sheet 408 is attached to the opening window so that dust, paper dust, and the like do not enter the housing 401 by the opening window.

The light source 202 is an LED generally called TOPVIEW type, and emits light radially from the light emitting surface with the surface normal direction as an optical axis. The LED of the light source 202 has a light distribution angle characteristic in which the light amount in the surface normal direction of the light emitting surface is maximized, and the light amount gradually decreases as the inclination from the surface normal increases. The light guide 403 is an optical element formed of acrylic resin. The spectroscopic optical system 206 is a concave reflection type diffraction grating, and is manufactured for vapor deposition of a reflection film such as aluminum and a reflection enhancement film such as SiO ₂ on a resin optical element manufactured by injection molding. The light receiving element 207 is an array of photoelectric conversion elements such as a plurality of Si photodiodes in the spectral direction. Hereinafter, each photoelectric conversion element is described as a pixel.

  Hereinafter, a colorimetry method using the spectral colorimetry unit 400 will be described. As shown in FIGS. 2A and 2B, the light emitted from the light source 202 is transmitted through the incident surface 403a of the light guide 403 in contact with the light source 202 and totally reflected upward by the reflecting surface 403b. The light is collected on the color patch 210 which is the test surface. The reflected light from the color patch 210 becomes scattered light, and a part thereof is incident on an anamorphic surface 403 f having a condensing function in a direction parallel to the spectral direction of the light guide 403. Incident light on the anamorphic surface 403 f is bent in a direction parallel to the surface to be measured by the reflecting surface 403 g and becomes a light beam to be detected which is formed into a substantially linear image on the slit 405. The to-be-detected light beam which has passed through the slit 405 becomes an incident light beam to the spectroscopic optical system 206, and after being dispersed by the spectroscopic optical system 206, a slit image is formed for each wavelength on the light receiving element 207 for receiving and detecting this dispersed light beam. It is an image. The slit image dispersed on each pixel of the light receiving element 207 arranged in an array is collected, and the spectral characteristic of the light source 202, the spectral sensitivity characteristic of the light receiving element 207, etc. are corrected to the signal detected by each pixel Then, signal processing is performed to calculate the color tone of the light flux to be detected.

  The present embodiment relates to means for installing the spectral measurement unit 400 in the image forming apparatus. According to this embodiment, downsizing of the spectral colorimetry unit 400 and cost reduction of the image forming apparatus can be realized without deteriorating the colorimetry accuracy.

Hereinafter, the characteristic configuration of the present embodiment will be described.
FIG. 3 is an explanatory view of a fixing method of the spectral colorimetry unit 400 in the present embodiment. The spectral colorimetry unit 400 is installed on the paper conveyance path of the image forming apparatus, and needs to be arranged at different positions during color measurement and normal image output (non-color measurement). Therefore, the spectral colorimetry unit 400 is attached to the holding member 500 and is configured to be movable integrally with the holding member 500. The holding member main body 501 is a casing made of resin, and provided with a Z seat surface 501a, an X seat surface 501c, a Y seat surface 501d, and a locking portion 501e. The base 502 is made of resin, and provided with a hole 502b, a locking portion 502e, and an engaging portion 502g. The holding member main body 501 and the base 502 constitute a holding member 500. The biasing means 503 is a metallic compression spring. The spectral colorimetry unit 400 is elastically urged in the Z direction with respect to the holding member main body 501 by the urging means 503. At that time, the biasing means 503 presses the pressed portion 401 b of the housing 401, and brings the Z seat surface 401 a of the housing 401 into contact with the Z seat surface 501 a of the holding member main body 501. In the X direction, the position of the spectrocolorimetry unit 400 is regulated within a predetermined range by the X bearing surface 401 c of the housing 401 and the X bearing surface 501 c of the holding member main body 501. The position of the spectrocolorimetry unit 400 is restricted within a predetermined range by the Y seat surface 401 d of the housing 401 and the Y seat surface 501 d of the holding member 501 in the Y direction. The base 502 holds the holding member main body 501 by locking the locking portion 502 e to the locking portion 501 e of the holding member main body 501. Here, the biasing means 503 biases the spectral colorimetry unit 400 by pressing the pressed portion 401 b facing the hole 502 b through the hole (opening) 502 b of the base 502. In order to reliably energize the spectral colorimetry unit 400 and to reliably perform the contact and separation operation, the urging means 503, the spectral colorimetry unit 400 and the holding member 500 are as follows. It is configured. That is, the positions of the pressed position by the urging means 503, the pressed portion 401b of the spectral colorimetry unit 400, the gravity center G1 of the spectral colorimetry unit 400, the gravity center G2 of the holding member main body 501, and the gravity center G3 of the base 502 are the same line L It is located on the top. At this time, the direction of the straight line L is equal to the direction of the urging force by the urging means 503 and the moving direction of the spectral measurement unit 400. The center of gravity of the holding member 500 including the holding member main body 501 and the base 502 is also located on the straight line L.

Since the color measurement is performed in a state in which the holding member main body 501 is in contact with the color patch 210, the spectral colorimetry unit 400 is urged to the holding member main body 501. The relative distance in the direction can be maintained with high accuracy. Here, the reason for maintaining the relative distance with high accuracy will be described. FIG. 4 shows the correlation between the light quantity of the detected light beam and the relative distance between the spectral measurement unit 400 and the color patch 210 in the Z direction. It can be seen from FIG. 4 that when the relative distance in the Z direction changes, the light amount changes. Since the change in the amount of light that causes deterioration of the colorimetric accuracy, color measurement, the relative distance has to be held with high accuracy so that Z _1. In the X and Y directions, relative position fluctuation is relatively insensitive to colorimetric accuracy, so it is not always necessary to regulate the position with high accuracy.

  Hereinafter, the contact and separation operation of the spectral colorimetry unit 400 will be described. FIG. 5 is an XZ sectional view of the displacement mechanism of the spectral colorimetry unit 400. As shown in FIG. The slide cam 504 is made of resin and is provided with an engagement surface 504 a and an engagement surface 504 b at different positions in the Z direction. Here, the slide cam 504 corresponds to the regulating member. The engagement surface 504a provided at a position close to the color patch 201 corresponds to the first engagement portion in the Z direction which is the direction of the urging force by the urging means 503, and is provided at a position distant from the color patch 201. The engaged surface 504b corresponds to the second engaging portion. The slide cam 504 is configured to be able to reciprocate in the X direction by drive means (not shown). The spectral colorimetry unit 400 and the holding member main body 501 are always pressed integrally in the Z direction by the biasing means 503.

  FIG. 5A shows the state at the time of color measurement. The engagement portion 502 g of the base 502 is engaged with the engagement surface 504 a of the slide cam 504. At this time, the spectral colorimetry unit 400 is held by the balance between the pressing force in the Z direction by the biasing unit 503 and the reaction force in the −Z direction that the holding member main body 501 that moves integrally receives from the color patch 210. Ru. At this time, the engaging portion 502 g of the base 502 is not in contact with the engaging surface 504 b of the slide cam 504. At the time of color measurement, the color patch 210 passes between the elastically urged holding member main body 501 and a paper conveyance guide (not shown). Therefore, the pressing force by the biasing means 503 needs to be suppressed to an appropriate size, and for example, about 100 gf is preferable.

FIG. 5B shows a state at the time of normal image output in which color measurement is not performed. The slide cam 504 is moved to a position different from the time of color measurement in the X direction, and the engagement portion 502 g of the base 502 is engaged with the engagement surface 504 b of the slide cam 504. At this time, since the base 502 receives a force in the -Z direction from the slide cam 504 at the engaging portion 502g, the spectral colorimetry unit 400 is separated from the color patch integrally with the holding member main body 501 and the base 502. Biased to position. As described above, the spectroscopic measurement device 400 is configured to be capable of reciprocating the contact position and the separated position by the slide cam 504 reciprocatingly moving in the X direction. In the present embodiment, the displacement mechanism includes the biasing means 203, the engaging portion 502g of the base 502, and the slide cam 504. Further, in the present embodiment, the spectral colorimetry device 20 is configured to include the spectral colorimetry unit 400, the holding member 500, the biasing unit 203, and the slide cam 504.
In this embodiment, biasing means for holding the spectral colorimetry unit 400 is also used as biasing means 503 for applying the contact force of the holding member main body 501. The effect of this configuration will be described using FIG. 6 (a) shows the configuration of this embodiment, FIG. 6 (b) shows the configuration for biasing the spectral colorimetry unit 600 with a screw, and FIG. 6 (c) shows the spectral colorimetry unit 700 with a linear elastic member S. It is the structure to turn on.

The first effect of the configuration of the present embodiment is that the measurement accuracy is not deteriorated when the spectral measurement unit 400 is urged to the holding member main body 501. In the configuration of FIG. 6B, the housing 601 is deformed by the shear stress at the time of screwing, and for example, the positional accuracy of the spectroscopic optical system 206 is deteriorated. Such positional change of the optical element causes deterioration of the color measurement accuracy. On the other hand, in the configuration of the present embodiment, the pressed portion 401b of the housing 401 is pressed by the urging means 503 with a force that is not too large, for example, about 100 gf. It does not get worse.
The second effect of the configuration of the present embodiment is the miniaturization of the spectral colorimetry device 20. In the configurations shown in FIGS. 6B and 6C, the fixing portions 601b and 701b need to be disposed outside the space responsible for spectral colorimetry in the XY plane. On the other hand, in the configuration of the present embodiment, the pressed portion 401b is disposed inside the space responsible for the spectral color measurement in the XY plane, and therefore, the spectral colorimetry device 400 can be miniaturized.
The third effect of the configuration of this embodiment is the cost reduction of the image forming apparatus. While the spectral colorimetry units 600 and 700 require a fixing means different from the biasing means 503, in the configuration of the present embodiment, another fixing means is not required, thus enabling cost reduction. Do.
In the present embodiment, a metal compression spring is used as the biasing means 503, but the invention is not limited to this.

[Image forming apparatus]
As a second embodiment, the case where the spectrometric device 20 is applied to a tandem-type color image forming apparatus employing an intermediate transfer belt will be described. The spectral colorimetry apparatus 20 of this embodiment has the same configuration as that of the first embodiment, and therefore the description thereof is omitted. FIG. 8 is a cross-sectional view showing a schematic configuration of an image forming apparatus to which the spectral measurement device 20 of this embodiment is applied. First, the operation of the image forming unit of the image forming apparatus of the present embodiment will be described with reference to FIG. Here, the configuration and operation of each image forming unit are substantially the same except that the colors of toner used (yellow (Y), magenta (M), cyan (C), and black (K)) are different. . Therefore, in the following description, when distinction is not particularly required, the suffixes Y, M, C, and K given to the reference numerals in FIG. 8 are omitted to indicate that they are elements provided for any color. Give a comprehensive explanation.

  The image forming unit of this embodiment includes a feeding unit 144, a photosensitive drum 131 as an image carrier for each color station, a charging roller 132 as a charging unit, a scanner unit 133, and a developing unit 138 as a developing unit. The image forming unit further includes an intermediate transfer belt 137, a drive roller 141 for driving the intermediate transfer belt 137, a tension roller 140, an auxiliary roller 142, a primary transfer roller 134, a secondary transfer roller 143, and a fixing unit 151. Furthermore, the image forming unit includes a printer controller 155 that controls an image forming operation. The photosensitive drum 131 is formed by applying an organic photoconductive layer on the outer periphery of an aluminum cylinder, and is rotated by transmitting the driving force of a driving motor (not shown), and the driving motor rotates the photosensitive drum 131 according to the image forming operation. Rotate in the arrow direction (clockwise direction) in the figure. In this embodiment, the image forming unit includes a photosensitive drum 137, a charging roller 132, a scanner unit 133, a developing unit 138, an intermediate transfer belt 137, a primary transfer roller 134, and a secondary transfer roller 143.

  When the control unit 155 receives an image signal (input signal), the recording medium P is fed from a feeding unit 144 (such as a cassette) by a feeding roller 145 or 146 to a conveyance path in the image forming apparatus. Thereafter, the recording medium P is temporarily held by a registration roller pair (hereinafter, simply referred to as a registration roller pair) 147 for synchronizing an image forming operation to be described later and the conveyance operation of the recording medium P, and then stopped and stopped. Do. On the other hand, the printer controller 155 causes the scanner unit 133 to form an electrostatic latent image corresponding to the received image signal on the surface of the photosensitive drum 131 charged to a constant potential by the action of the charging roller 132.

  The developing device 138 is a means for visualizing the electrostatic latent image formed on the photosensitive drum 131, and uses toners of yellow (Y), magenta (M), cyan (C) and black (K) for each station. To develop the electrostatic latent image. Each developing device 138 is provided with a sleeve 135, and a developing voltage for visualizing the electrostatic latent image is applied to the sleeve 135. Thus, the electrostatic latent image formed on the surface of each photosensitive drum 131 is developed as a single color toner image by the action of each developing device 138. The photosensitive drum 131, the charging roller 132, and the developing device 138 are integrally configured, and are attached to the image forming apparatus main body in the form of a toner cartridge 139 which can be detached from the image forming apparatus main body.

  The intermediate transfer belt 137 is in contact with the photosensitive drums 131, and rotates in synchronization with the rotation of the photosensitive drums 131 in the arrow direction (counterclockwise direction) of FIG. The single-color toner image developed on the photosensitive drum 131 is sequentially transferred to the intermediate transfer belt 137 (primary transfer) by the action of the primary transfer voltage applied to the primary transfer roller 134 and superimposed on the intermediate transfer belt 137. It becomes a multicolor toner image. Thereafter, the multicolor toner image formed on the intermediate transfer belt 137 is conveyed to a secondary transfer portion (nip portion) formed by the drive roller 141 and the secondary transfer roller 143. On the other hand, the recording medium P, which has been on standby in the state of being nipped by the registration roller pair 147, is conveyed to the secondary transfer portion in synchronization with the multicolor toner image on the intermediate transfer belt 137 by the action of the registration roller pair 147. Ru. Then, the multicolor toner image on the intermediate transfer belt 137 is collectively transferred onto the recording medium P by the action of the secondary transfer voltage applied to the secondary transfer roller 43 (secondary transfer).

  The fixing unit 151 fuses and fixes the transferred multicolor toner image while transporting the recording medium P, and fixes the fixing roller 151a for heating the recording medium P and the pressing force of the recording medium P against the fixing roller 151a. The pressure roller 151 b is provided. The fixing roller 151 a and the pressure roller 151 b are formed in a hollow shape, and heaters 151 ah and 151 b h are respectively incorporated therein. The recording medium P holding the multicolor toner image is conveyed by the fixing roller 151 a and the pressure roller 151 b, and heat and pressure are applied to fix the toner on the surface of the recording medium P.

  When the recording medium P on which the toner image is fixed is discharged to the discharge tray 52 by the discharge roller 150 and the image forming operation is completed or when the image formation on the second surface of the recording medium P is performed. It is switched back by the discharge roller 150 (returned and conveyed). When the image forming operation on the second surface of the recording medium P is performed, the recording medium P holding the multicolor toner image on the first surface (one side) passes through the duplex conveying path D by the switchback operation by the discharge roller 150. Then, the resist roller pair 147 is once again gripped by the registration roller pair 147, and is stopped and stands by. Thereafter, the above-described series of image forming operations are performed to form an image on the second surface of the recording medium P. The cleaning device 148, which is a cleaning unit, cleans the toner not transferred to the recording medium P and remaining on the intermediate transfer belt 137. The toner collected by the cleaning device 148 is stored in the cleaner container 149.

The spectral colorimetry apparatus 20 of this embodiment is disposed at the central position in the longitudinal direction in the double-sided conveyance path D for the purpose of colorimetry of the color patch constituting the colorimetry patch image T formed on the recording medium P. ing. Here, the longitudinal direction means a direction (rotational axis direction of the photosensitive drum 131) orthogonal to the conveyance direction on the image forming surface of the recording medium P conveyed on the double-sided conveyance path D. In this embodiment, the spectral colorimetry apparatus 20 is downstream of the fixing unit 151 on which the recording medium on which the color patch is formed on the first surface is fixed, and in the image forming unit to form an image on the second surface. It is provided in the double-sided conveyance path D for conveying the recording medium. Further, in the image forming apparatus of the present embodiment, is the printer controller 155 provided in the image forming apparatus appropriately making the color reproducibility of the color patch on the basis of the measurement result by the spectral colorimetry device 20? Make a color calibration if necessary.

Reference Signs List 20: spectral colorimetry device 202: light source 206: spectral optical system 207: light receiving element 210: color patch (surface to be detected) 400: spectral colorimetry unit 401: housing 403: light guide 500 ... holding member, 501 ... holding member main body, 502 ... base, 503 ... biasing means, 504 ... slide cam

Claims (10)

A light source; an illumination optical system for guiding a light flux from the light source onto a test surface; a light guide optical system for guiding reflected light from the test surface; and an incident light flux from the light guide optical system A spectral colorimetry unit having a spectral optical system for spectral separation, and a light receiving element for receiving and detecting a light flux dispersed by the spectral optical system;
A holding member for holding the spectral colorimetry unit;
A displacement mechanism for moving the spectral colorimetry unit to a first position during color measurement and a second position during non-color measurement;
Biasing means for holding the spectral colorimetry unit on the holding member by urging the spectral colorimetry unit with respect to the holding member in a direction moving from the second position to the first position; And a spectral colorimetry device.   The spectrocolorimetry apparatus according to claim 1, wherein the biasing unit biases the holding member via the spectrometric colorimetry unit.   The spectral colorimetry unit is positioned at the first position by bringing the holding member holding the spectral colorimetry unit into contact with the test surface by the urging means. 2. The spectral colorimetry device according to 2. The displacement mechanism includes an engagement portion provided on the holding member, and a regulation member having an engagement portion engaged with the engagement portion and regulating the position of the holding member.
The engaging portion of the restricting member is provided at a first engaging portion provided at a position near the test surface and at a position away from the test surface in the direction of the urging force by the urging means. Including a second engaging portion,
When the second engaging portion of the regulating member engages with the engaging portion of the holding member, the holding member holding the spectral colorimetry unit resists the biasing force of the biasing unit. The spectrocolorimetry apparatus according to claim 2 or 3, wherein the spectrocolorimetry apparatus is located at the second position. The holding member has an opening,
The spectral colorimetry unit includes a pressed portion in which the biasing unit presses the spectral colorimetry unit through the opening.
The center of gravity of the spectral colorimetry unit overlaps with the pressed portion when viewed in a plane orthogonal to the direction of the urging force by the urging means. Spectral colorimetry device.   The direction of a straight line connecting the center of gravity of the spectrocolorimetry unit and the center of gravity of the holding member is equal to the direction of urging force by the urging means, and is also equal to the direction of movement of the spectrocolorimetry unit. The spectrocolorimetry apparatus according to claim 5.   The spectral colorimetry apparatus according to any one of claims 1 to 6, wherein the spectral colorimetry unit measures the chromaticity of the test surface. An image forming unit that forms an image on a recording medium;
An image forming apparatus comprising: the spectral measurement device according to any one of claims 1 to 7, wherein the recording medium on which the image is formed is a test surface. The image forming unit forms a toner image as the image.
The image forming apparatus according to claim 8, wherein the spectral colorimetry device is provided downstream of a fixing unit that fixes the toner image on the recording medium. The image forming unit forms a toner image as the image on both sides of the recording medium,
The spectral colorimetry apparatus is configured to form a toner image on a second surface of the recording medium downstream of a fixing unit that fixes the toner image formed on the first surface of the recording medium to the recording medium. 10. The image forming apparatus according to claim 9, wherein the image forming unit is provided in a conveyance path for conveying the recording medium.