JPH01118866A - Hue adjusting device - Google Patents

Abstract

PURPOSE:To obtain a color copied image which is more faithful to an original and pleases a user's fancy by making it possible to adjust color separation characteristic in itself at the time of separating the color of the original image and exposing it. CONSTITUTION:When the angles of multilayer thin film interference filters 21-23 functioning as spectral means are changed, light which executes scanning and exposure is refracted by said filters according to the change of the angles to change an optical path. When the optical path for scanning and exposing the image of the original 1 on a photosensitive drum 9 is made different because of the color of light whose color is separated, a toner image finally transferred on a transfer sheet is deviated and color slurring occurs in a copied image. Then the optical path is corrected corresponding to the change of the angles of the multilayer thin film interference filters 21-23 by an optical path correction glass 26 functioning as an optical path correction means, so that the images of all the colors are made to be exposed in the same position of the photosensitive drum 9. Since it is made possible to adjust the color separation characteristic in itself at the time of separating the color of the image of the original 1 and exposing it, the adjustment of the hue which is more faithful to the original and pleases the user's fancy can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] This invention relates to a color tone adjustment device used in color electrophotographic copying machines and the like.

[Prior Art] Conventionally, the above-mentioned color electrophotographic copying machine separates an image of a document into a plurality of colors and exposes the image onto a photoreceptor drum, and then prints a plurality of colors on the photoreceptor drum using a well-known electrophotographic process. There is a method in which a color copy image is obtained by sequentially forming toner images corresponding to the separated colors and transferring these toner images onto a transfer sheet in an overlapping manner. By the way, in such a color copying machine, the spectral characteristics of the light source that illuminates the document, the spectral characteristics of the filter that performs color separation, the spectral characteristics of the photoreceptor drum, or the mixability and color development of the toner used are It is unique to each copier and is determined by the materials used. Furthermore, the spectral characteristics of the light source, filters, and other members are not necessarily ideal, so the colors of the original cannot be completely reproduced in a color copy image. Furthermore, in the case of color copying, unlike the copying of normal black and white images, the subjective color preference of the person making the copy becomes important, and in some cases, the user may desire to reproduce colors different from those of the original.

Therefore, a color tone adjustment device is used to adjust the color reproducibility of a color copy image, and this type of color 1:1
! ! The following devices are available. In other words, by adjusting the exposure amount of the original document exposed to the photoreceptor drum, and by adjusting the development bias when developing the electrostatic latent image formed on the photoreceptor drum, the color tone of the image can be adjusted. There are some things that need to be adjusted.

[Problems to be Solved by the Invention] However, such prior art has the following problems. That is, when adjusting the exposure amount of the original exposed on the photoreceptor drum as in the former case, it is possible to obtain a desired color tone to some extent by changing m* of the image corresponding to each color separated image. However, the fair color body exposed to the photoreceptor drum is determined by the spectral characteristics of the filter that performs color separation, and since these spectral characteristics are not ideal, there is still the problem that the desired color tone cannot be obtained. There was a point. In other words, no matter how much the exposure amount is changed, the exposed light itself does not accurately reflect the original image (color separation), so it is difficult to faithfully reproduce the original image or to match the user's preferences. Color reproducibility could not be obtained. Furthermore, even if the development bias is adjusted when developing an electrostatic latent image, as in the latter case, the density of each color toner used for development is changed, so the color reproducibility will depend on the usage. This is largely determined by the characteristics of the toner used, and there is a problem in that it is not possible to faithfully reproduce the original image or obtain color reproducibility that meets the user's preference.

[Means for Solving the Problems] Therefore, the present invention has been made to solve the above-mentioned problems of the prior art. To provide a color tone adjustment device capable of obtaining a color copy image that is more faithful to the original and more suited to the user's preference by making the color separation characteristics itself adjustable.

That is, the present invention provides a color tone adjustment device for use in an image forming apparatus that separates an image of a document into colors and exposes it onto an image carrier to obtain a color copy image. A spectroscopic means that can adjust the spectral characteristics by changing the angle formed with the optical path, and an optical path correction means that corrects the optical path according to the change in the angle of the spectroscopic means are interposed in the optical path. There is.

As the spectroscopic means, a multilayer thin film interference filter is used, for example, but it is not limited thereto, and an optical color glass filter may also be used.

Further, the spectroscopic means may include a plurality of filters having different spectral characteristics arranged radially around an axis, and may be switched by rotating these filters. However, the present invention is not limited to this, and switching may be performed by moving a plurality of filters linearly.

As the optical path correction means, for example, glass for optical path correction is used.

The spectroscopic means and the optical path correction means are interposed, for example, on the exit side of a lens for exposing an image of an original onto an image carrier, but the invention is not limited thereto. Of course, it is also possible to interpose it on the incident side.

Further, the order in which the spectroscopic means and the optical path correction means are interposed in the optical path may be either the order of the spectroscopic means and the optical path correction means or the reverse order.

[Function] In this invention, by changing the angle of the spectroscopic means, the spectral characteristics of the spectroscopic means itself are adjusted, and
A change in the optical path due to a change in the angle of the spectroscopic means is corrected by the optical path correction means.

[Example] The present invention will be explained below based on illustrated embodiments.

FIG. 2 shows a color electrophotographic copying machine to which the color tone adjustment device according to the present invention can be applied. In the figure, reference numeral 1 denotes an original placed on a contact glass 2 , and an image of this original 1 is illuminated by a light source 3 . A reflected light image from the original 1 is scanned and exposed onto a photoreceptor drum 9 as an image carrier via a full rate mirror 4, a half rate mirror 5.6, a lens 7, and a fixed mirror 8. that time,
A color tone adjustment device 10 according to an embodiment of the present invention is interposed between the lens 7 and the fixed mirror 8, and by sequentially switching the color tone adjustment device @10, the image of the original 1 is separated into colors. In addition, the color tone of the light used for scanning exposure can be adjusted. The photosensitive drum 9 is charged in advance by the corona charger 11 prior to image exposure, and then an electrostatic latent image is formed by exposing the image of the original 1 as described above. This electrostatic latent image is developed by one of the developing devices 12, 13, and 14 for yellow, magenta, and cyan colors arranged around the photoreceptor drum 9, which corresponds to the color of the color-separated image. The toner image is then transferred onto a transfer sheet held on a transfer drum, which will be described later. Thereafter, residual toner is removed from the surface of the photosensitive drum 9 by a cleaner 15, and image formation with different colors is repeated a predetermined number of times.

A transfer drum 16 is rotatably arranged near the photosensitive drum 9, and a portion of the transfer drum 16 that holds a transfer sheet 17 is formed of a dielectric material. The transfer drum 16 grips the leading edge of the transfer paper 17 with a gripper 18 and electrostatically attracts and holds the transfer paper. A transfer corotron 19 is disposed inside the transfer drum 16 at a position closest to the photoreceptor drum 9, and transfers the toner image formed on the photoreceptor drum 9 to the transfer corotron 19 held on the transfer drum 16. It is configured to electrostatically transfer onto the transfer paper 17.

Then, the yellow 0 is sequentially transferred onto the photoreceptor drum 9.
After sequentially overlapping and transferring the toner images of +, cyan, and magenta onto the transfer paper 17 held on the transfer drum 16, the transfer paper 17 is separated from the transfer drum 16,
A fixing device 20 fixes the toner image on the transfer paper 17 to obtain a color image.

By the way, the color tone adjustment device 10 according to this embodiment is a spectral means that is interposed in the optical path for exposing the image of the original 1 onto the photoreceptor drum 9, and is capable of adjusting the spectral characteristics by changing the angle formed with the optical path. and an optical path correction means for correcting the optical path according to the angle change of the spectroscopic means. That is, on the exit side of the lens 7, three multilayer thin film interference filters 21, 22, and 23 each having spectral characteristics of blue, red, and green are provided as spectroscopic means.
Color separation filters 2 fixed radially around the rotating shaft 24
5 and an optical path correction glass 26 as an optical path correction means are interposed.

The multilayer thin film interference filter 21.22.23 is formed by forming multiple thin films on a substrate made of glass or the like. As a result, the wavelength of the interfering light changes due to the multilayer thin film, and the spectral characteristics change as shown in FIGS. 3, 4, and 5, respectively. In Figures 13, 14 and 5, 40
4 shows the spectral sensitivity characteristic of the photosensitive drum 9, and 41 shows the spectral irradiance characteristic of the halogen lamp used as the light source 3. Also, 42a, 42b.

42c shows the spectral transmittance characteristics when the red, green, and blue multi-layer interference filters are tilted by 22.5 degrees, 0 degrees, and 451 yen, respectively.
shows the effective exposure amount when red, green, and blue multi-meter thin-film interference filters are tilted at 22.5 degrees, 0 degrees, and 45 degrees, respectively.

As shown in FIG. 6, a stepping motor 27 is connected to the rotating shaft 24 of the color separation filter 25, and by rotationally driving the stepping motor 27, the angle of the multi-meter thin film interference filter 21, 22, 23 is changed. are each adjustable.

The optical path correction glass 26 is made of a transparent glass plate with a predetermined thickness, and by changing its angle,
It is possible to change the optical path by refracting light. That is, the multilayer thin film interference filter 21.
When the angle of 22.23 is changed, the scanning exposure light is refracted by this filter and the optical path changes accordingly.

However, if the optical path for scanning and exposing the image of the original 1 onto the photoreceptor drum 9 differs depending on the color of the light to be separated, the toner image that is ultimately transferred onto the transfer paper will be misaligned.
Color misalignment occurs in the copied image.

Therefore, this optical path correction glass 26 corrects the optical path in response to changes in the angles of the multilayer thin film interference filters 21, 22, and 23, so that images of all colors are exposed at the same position on the photoreceptor drum 9. It is for the purpose of This optical path correction glass 26 has a rotating shaft 28 as shown in FIG.
is fixed to the rotary shaft 28, and a sting motor 29 is connected to one end of the rotating shaft 28. Then, by appropriately rotating this stepping motor 29, the optical path correction glass 2
By changing the angle 6, the optical path can be adjusted.

FIG. 8 is a block diagram showing a control circuit of this color tone adjustment device. In the figure, 30 is a color WA adjustment button provided on the operation panel of the copying machine, and this color tone adjustment button 3
By operating 0, the user can adjust the color tone to suit his/her preference. That is, as shown in FIG. 9, this color tone adjustment button 30 is made up of up/down keys, and the up/down key 3 is used to select which tone among the color tones displayed on the display section 30a you wish to adjust.
0, and the selected result is displayed by lighting the display lamp 30b. 31 detects the color tone specified by the user by pulses etc. sent from the color tone adjustment button 30, and controls the stepping motor 2.
This is for controlling the amount of rotation of 7 and 29. This control circuit 31 includes multilayer single-film interference filters 21.22.2.
The rotation amount of the stepping motor 29 is controlled according to the rotation amount of the stepping motor 27 that changes the angle of the document 1, so that the optical path for exposing the image of the document 1 onto the photosensitive drum 1 does not change at all times. 27 and 29 are the stepping motors mentioned above.

In the above configuration, the color tone adjusting device according to this embodiment adjusts the tone of a color image to be copied in the following manner. That is, a desired original 1 is placed on the contact glass 2.
The original 1 is placed on the photoreceptor drum 9, and the original 1 is illuminated by the light source 3 to scan and expose the image of the original 1 onto the photoreceptor drum 9. At this time, multilayer single-film interference filters 21, 22, and 23 of predetermined colors are interposed as color separation filters 25 in the optical path, and the image of the original 1 is color-separated into blue, red, and green and exposed. A color copy image is formed on transfer paper 17 by a well-known electrophotographic process.

Next, in order to adjust the tone of the color copy image thus obtained, the user adjusts the tone adjustment button 30 provided on the operation panel according to the user's preference.

For example, if it is desired to shift the red color of the original 1 to the green side and copy it, or if the red color tone is weakened and the copy is made, the red tone adjustment button 30 is set to the green side. By doing this, the control circuit 31 rotates the stepping motors 27 and 29 by a predetermined number of rotations, and rotates the multilayer single-film interference filter 22 at 0 degrees when the image of the original 1 is separated into red colors and exposed. By rotating the filter 22, the spectral characteristics of the filter 22 are shifted to the red side as shown at 42b in FIG. 3, and the optical path is corrected by the optical path correction glass 26. Then, by scanning and exposing the image of the original 1, a red image is exposed on the photosensitive drum 9 with a red tone weaker than that of the normal filter position, and an electrostatic latent image is formed. Therefore, this latent image is
The image is developed with cyan toner, which is a complementary color to red, and a color with cyan emphasized more than a normal image, that is, a color tone shifted to the green side, is obtained.

Note that color tone adjustment is performed in the same manner as above for other blue and green colors.

Here, as described above, the multilayer thin film interference filters 21, 22.
By rotating 23, the filter enters tJ4ttl.
The optical axis position and the position after ejection are shifted, and the exposure position on the photoreceptor drum 9 is shifted for each color, resulting in color shift in the copied image. For this reason, as shown in FIGS. 10 and 11, multiple It'lN! Interference filter 21.22.2
The optical path correction glass 26 is rotated in conjunction with the rotation of step 3. At that time, as shown in FIG. 10, when the angle of the multi-m1ss interference filter is small, the angle of the optical path correction glass 26 is increased, and as shown in FIG. 11, when the angle of the multilayer thin film interference filter is large, , optical path correction glass 26
Set so that the angle of As a result, the positional relationship between the optical axis entering the color separation filter 25 and the optical axis exiting the color separation filter 25 remains unchanged, eliminating the above-mentioned disadvantage.

In this way, when adjusting the color tone, the multilayer thin film interference filters 21, 22, .
Since the spectral characteristics of 23 are made to be different, it is possible to adjust the color tone in a way that cannot be obtained by simply changing the density of a specific color as in the conventional case. That is, in order to change the spectral characteristics of the filter that color-separates the image of the document 1, the image that is color-separated and exposed on the photoreceptor drum 9 is exposed while being shifted toward the green side if it is red, for example. Because it is possible to change the color tone in terms of width and color density, it is now possible to change the quality in terms of the wavelength of the exposed image, which allows for a wider range of user-friendliness. The color tone can be adjusted within a range that suits your preferences. Therefore, it is possible to perform color tone adjustment that is more faithful to the original than in the past and that matches the user's preference.

Note that when using an optically colored glass filter as a spectroscopic means, when the angle is increased, the spectral characteristics of red shift toward longer wavelengths, green has a narrower bandwidth, and blue shifts toward shorter wavelengths. The rest of the process is the same as described above.

[Effects of the Invention] This invention has the above-described structure and operation, and it is possible to adjust the color separation characteristics itself when the original image is color-separated and exposed. It is possible to adjust the color tone according to the user's preference.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a color tone adjustment device according to the present invention, Fig. 2 is a block diagram showing a color electrophotographic copying machine to which the same device is applied, and Fig. 3 shows the spectral characteristics of a red filter. Figures 4 and 5 are graphs showing the spectral characteristics of the blue and green filters, respectively. Figure 6 is a perspective view of the color separation filter drive mechanism, and Figure 7 is the drive of the optical path correction glass. FIG. 8 is a block diagram showing the control circuit, FIG. 9 is a plan view showing the operation panel, and FIGS. 10 and 11 show different angle adjustments of the multi-11i111R interference filter and optical path correction glass. It is a side view which shows a state. [Explanation of symbols 1 1... Original 9... Photosensitive drum 21.22.23... Multilayer thin film interference filter 26...
・Optical path correction glass patent applicant: Fuji Xerox Co., Ltd.
Patent Attorney Satoshi Nakamura G11 (2 others) Figure 3 Wavelength (rwm) Figure 6 Figure 7 Figure 8 Figure 4 Wavelength (ns) Figure 5 Wavelength (+m)

Claims (1)

[Claims] In a color tone adjustment device used in an image forming apparatus that separates the original image into colors and exposes it onto an image carrier to obtain a color copy image, an optical path is A color tone adjustment device characterized by interposing a spectroscopic means that can adjust spectral characteristics by changing the angle formed by the spectroscopic means, and an optical path correction means that corrects the optical path according to the change in the angle of the spectroscopic means.