JPH113001A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image forming device by which quality is not deteriorated even when plain paper is selected at the time of forming a color image and expenses are not wastefully required even when recording paper only used for color printing is selected at the time of forming a black-and-white image by automatically selecting the suitable recording paper respectively at the time of forming the black-and-white image and at the time of forming the color image. SOLUTION: An image decision part 3 to which information about a selected reading method is given judges that it is the time when the black-and-white image is formed as a printed image in the case of selecting a black-and-white image reading method and judges that it is the time when the color image is formed in the case of selecting a color image reading method. Information about the kind of paper housed in paper feeding trays 1a to 1d is previously set in a paper kind setting part 2. Based on the judged result by the decision part 3 and the information about the set kind of paper in the setting part 2, a paper kind selecting part 4 selects the paper feeding tray 1 in which the plain paper is housed when the next printed image is the black-and-white image and selects the paper feeding tray 1 in which the recording paper only used for color printing is housed when it is the color image. Then, the recording paper in the paper feeding tray 1 is carried to a pair of resist rollers and the image is written on the recording paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a color electrophotographic copying machine, a color printer, and a color facsimile, and more particularly, it can select and set a paper type of a recording paper stored in a paper feed tray. The present invention relates to a color image forming apparatus having functions.

[0002]

2. Description of the Related Art In a color image forming apparatus having a function of forming a black-and-white and a color image, a recording sheet dedicated to color is used to maintain the color quality at the time of forming a color image. Not cheap plain paper is used. For this reason, when a black and white image and a color image are formed by a color image forming apparatus, two types of recording paper are prepared in the apparatus: a recording paper dedicated to color printing and a plain paper used for forming a black and white image. Further, this type of color image forming apparatus has a function of selecting a paper feed tray according to a recording paper size specified by a host computer, and a recording paper size is selected from a read original size and a set scaling factor, It has a function to select a paper feed tray to which a suitable recording paper is delivered.

[0003]

However, in the above-described conventional color image forming apparatus, if the paper feed tray is selected only by the recording paper size, plain paper is selected at the time of forming a color image, or color-only is used at the time of forming a monochrome image. When a color paper is selected, a recording paper selection error occurs, plain paper is selected at the time of color image formation, and the image quality is degraded. There was a problem of hanging. Therefore, the problem to be solved by the present invention is to solve the above-mentioned drawbacks of the conventional technology, and to automatically select a recording paper suitable for each of black and white image formation and color image formation, thereby enabling color printing. It is an object of the present invention to provide a color image forming apparatus in which color-specific recording paper is selected at the time of forming a black and white image so that unnecessary costs are not reduced, without reducing the quality by selecting plain paper at the time of image formation.

[0004]

According to a first aspect of the present invention, there is provided a color image forming apparatus having a function of forming a black and white and a color image. Paper type setting means for setting the paper type of the recording paper stored in the paper feed tray; image determining means for determining whether the image to be formed is a black-and-white image or a color image; and determination by the image determining means Paper type selecting means for selecting a paper feed tray for storing a recording sheet of an optimum paper type from the paper feed tray based on the result. According to a second aspect of the present invention, in the color image forming apparatus according to the first aspect, the paper type setting unit performs the setting based on a setting state of a paper type setting dial attached to the paper feed tray. It is characterized by: According to a third aspect of the present invention, in the color image forming apparatus according to the first aspect, the paper type setting unit performs the setting in accordance with an input from an operation panel unit. According to a fourth aspect of the present invention, in the color image forming apparatus according to any one of the first to third aspects, the recording sheet of the optimum paper type is selected from the paper feed tray by the paper type selection unit. A display means for displaying that selection is impossible when selection is not possible is provided.
According to a fifth aspect of the present invention, in the color image forming apparatus according to any one of the first to fourth aspects, the recording paper of the optimum paper type is selected from the paper feed tray by the paper type selection unit. When you cannot select, one of the paper trays
And a tray designating means for designating one of them as a paper feed tray for image formation.

According to the above construction, according to the first aspect of the present invention, the paper type setting means sets the paper type in advance in accordance with the paper supply tray in which plain paper and color-specific recording paper are stored. The image determination unit determines whether the image to be formed is a black-and-white image or a color image.The paper type selection unit selects a plain paper feed tray if the image is a black-and-white image, and a color image if the image is a color image. Since the dedicated paper feed tray is selected, the optimum recording paper suitable for the image is automatically selected. According to a second aspect of the present invention, in addition to the color image forming apparatus according to the first aspect, the paper type setting means sets a paper type setting dial attached to the paper feed tray. Since the setting is performed according to the state, if the user sets the paper type setting dial in advance according to the paper type when the recording paper is stored in the paper feed tray, The paper type is automatically set by the paper type setting means. Therefore, even if the paper feed tray is moved to another paper feed place, it can be used without changing the paper type setting. Claim 3
According to the invention described in (1), in addition to the invention of the color image forming apparatus configured as in claim 1, the paper type setting means performs setting in accordance with an input from the operation panel means. The user can easily set and change the paper type by operating the operation panel means. Also,
According to a fourth aspect of the present invention, in addition to the invention of the color image forming apparatus according to any one of the first to third aspects, recording of a paper type optimized from the paper feed tray by the paper type selecting means. When the paper cannot be selected, the display means for displaying that the paper cannot be selected is provided, so that the user can immediately recognize that the operation has become abnormal by looking at the display means, and replace the recording paper with an optimal one. Alternatively, the next corresponding operation such as stopping the image formation can be immediately performed. According to a fifth aspect of the present invention, in addition to the invention of the color image forming apparatus according to any one of the first to fourth aspects, the paper type selecting means optimizes the paper type from among the paper feed trays. If the recording paper of the optimum paper type is out of paper, there is provided a tray designating means for designating one of the paper supply trays as the paper supply tray used for image formation when the recording paper of the type cannot be selected. Even at this time, image formation can be performed using recording paper of another stored paper type.

[0006]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing the internal structure of a color laser printer, which is one type of a color image forming apparatus to which the present invention is applied. The color laser printer 100 includes an image forming unit 101 and a paper feeding unit 102. The image forming unit 101 includes a writing optical unit 20, a photoconductor 21, a rotary developing device 31, an intermediate transfer belt 37, a paper transport belt 45, a fixing device 46, and the like. Writing optical unit 20
Is to convert color image data sent from the outside into an optical signal, perform optical writing corresponding to the image data, and form an electrostatic latent image on the photoconductor 21 as an image carrier, Laser light emitting means (laser diode) 22 and its light emission drive control unit (not shown), borgon mirror 23 and its rotation motor 24, f / Θ lens 25 and reflection mirror 2
6, etc. The photoconductor 21 rotates in a counterclockwise direction as indicated by an arrow A. Around the photoconductor cleaning unit 27, a static elimination lamp 28, a potential sensor 30 as a developing density pattern detecting unit, and a developing unit (a developing unit in the example of FIG. 1) selected from a rotary developing device 31 as a developing unit. Device 32), an intermediate transfer belt 37 as an intermediate transfer medium, and the like. The intermediate transfer medium is not limited to a belt-like medium, but may be a drum-like medium.

The rotary developing device 31 comprises a black developing device 33, a cyan developing device 34, a magenta developing device 35, a yellow developing device 36, and a rotary drive (not shown) for rotating each developing device. I have. Each developing device includes a developing sleeve that rotates by contacting an ear of the developer with the surface of the photoconductor 21 in order to visualize the electrostatic latent image, and a developing sleeve that rotates to pump up and agitate the developer. It is composed of paddles and the like. In the standby state, the rotary developing device 31 is set at the position of black development, and when the processing of the received image data is completed, light writing by a laser beam based on the image data and formation of an electrostatic latent image are started ( Hereinafter, an electrostatic latent image based on black image data is referred to as a black latent image, and the same applies to cyan, magenta, and yellow. In order to develop from the leading end of the black latent image, before the leading end of the latent image reaches the developing position of the black developing device, the rotation of the developing sleeve is started to develop the black latent image with black toner. Thereafter, the developing operation of the black latent image area is continued, but when the rear end portion of the latent image passes the black developing position, the rotary developing device quickly moves from the developing position for black to the next color developing position. 31 rotates. The above operation is completed at least before the leading end of the latent image based on the next image data arrives.

When the image forming cycle is started, first, the photosensitive member 21 is turned counterclockwise as indicated by an arrow, and
The intermediate transfer belt 37 is rotated clockwise by a drive motor (not shown). Intermediate transfer belt 37
, A black toner image, a cyan toner image, a magenta toner image, and a yellow toner image are formed, and finally black (Bk), cyan (C),
Magenta (M) and yellow (Y) are superimposed on the intermediate transfer belt 37 in this order to form a toner image. Here, in order to reduce the time required to align the leading edge of the image when forming the superimposed toner image as described above, the support roller of the intermediate transfer belt 37 is moved so that the intermediate transfer belt 37 is exposed to light. The intermediate transfer belt 37 is fast-forwarded while being separated from the body 21 and in this separated state.

First, black image formation is performed as follows. The charger 29 as charging means uniformly charges the photoconductor 21 with negative charges to about -700 V by corona discharge (charging step). Subsequently, the laser diode 22 performs raster exposure based on the black signal (exposure step). As described above, when the raster exposure is performed, the exposed portion of the photoconductor 21 that is initially uniformly charged loses the charge proportional to the exposure light amount, and an electrostatic latent image is formed. The intermediate transfer belt 37 includes a driving port roller 38, transfer opposing port rollers 39 and 40,
It is stretched over the cleaning opposing roller 41 and the driven roller group, and is driven and controlled by a drive motor (not shown). The black toner image formed on the photoconductor 21 is transferred to the surface of the intermediate transfer belt 37 that is driven at a constant speed in a state of contact with the photoconductor 21 by an intermediate transfer corona discharger 42 as a primary transfer unit ( Primary transfer step). Hereinafter, the transfer of the toner image from the photoconductor 21 to the intermediate transfer belt 37 is referred to as primary transfer.

A small amount of untransferred residual toner present on the photoconductor 21 is cleaned by the photoconductor cleaning unit 27 in preparation for reuse of the next color of the photoconductor 21. The collected toner is stored in a waste toner tank (not shown) via a collection pipe. The black, cyan, magenta, and yellow toner images sequentially formed on the photoconductor 21 are accurately and sequentially aligned on the intermediate transfer belt 37 to form a four-color superimposed belt transfer image. Using the corona discharger 43 for transfer as a secondary transfer means, batch transfer is performed on recording paper as a recording medium (secondary transfer step). On the photoconductor 21 side, the process proceeds to the cyan process after the black process. At that time, the processing of the data of the cyan image starts at a predetermined timing, and a cyan latent image is formed by writing a laser beam using the image data. The cyan developing device 34 rotates the rotary developing device 31 with respect to the developing position after the previous black developing rear end portion passes and before the leading end of the cyan latent image arrives.
The cyan latent image is visualized with cyan toner. Thereafter, the development of the cyan development area is continued, but when the rear end of the latent image passes, the rotation operation of the cyan development unit is performed in the same manner as in the case of the black developing device 33 described above. This is also completed before the leading end of the magenta latent image arrives. In the magenta and yellow processes, the respective image data processing, latent image formation, and development operations are the same as those in the above-described black and cyan processes, and a description thereof will be omitted.

Transfer corona discharger 4 as secondary transfer means
Numeral 3 applies a DC or AC + DC component by a corona discharge method to transfer the overlapping toner image on the intermediate transfer belt 37 onto a recording medium. The paper feed unit 102 is provided with a plurality of paper feed trays 1a, 1b, and 1c. Also,
A paper feed tray 1d is also provided below the image forming unit 101. These paper feed trays 1a to 1d store recording papers P of different sizes and recording papers P of different paper types in a distinguished manner. , Paper feed rollers 51, 52, 5
The sheet is fed and conveyed in the direction of the registration roller pair 55 by 3 or 54. Reference numeral 60 in the figure denotes a manual paper feed tray for OHP recording paper, thick paper, and the like. The recording paper P is fed from the paper feed port of any one of the selected paper feed trays at the time when the image formation is started, and is made to stand by at the nip portion of the registration roller pair 55. Then, the transfer corona discharger 43
When the leading end of the toner image on the intermediate transfer belt 37 is approaching, the registration roller pair 55 is driven such that the leading end of the recording paper coincides with the leading end of the image, and the registration of the paper and the image is performed. In this way, the recording paper P is superimposed on the intermediate transfer belt 37 and passes over the transfer corona discharger 43 connected to the positive potential side. At this time, the recording paper is charged with a positive charge by the corona discharge current, and a substantial part of the toner image is transferred onto the recording paper P. Subsequently, when the recording paper P passes through a portion of a not-shown neutralization brush arranged on the left side of the transfer corona discharger 43 in the drawing, the recording paper P is neutralized,
The sheet is separated from the intermediate transfer belt 37 and moves to the paper transport belt 45.

The recording paper P on which the four-color superimposed toner image has been collectively transferred from the intermediate transfer belt 37 is conveyed to a fixing device 46 by a paper conveyance belt 45, and a fixing opening roller 47 and a pressure opening which are controlled to a predetermined temperature. The toner image is melted and fixed at the nip portion with the roller 48, sent out of the apparatus through the discharge roller pair 49, and stacked face up on a storage tray (not shown) to obtain a full-color image. The surface of the photoconductor 21 after the image is transferred to the intermediate transfer belt 37 is cleaned by a photoconductor cleaning unit 27 including a brush roller and a rubber blade, and is uniformly discharged by a discharge lamp 28.
Intermediate transfer belt 37 after transferring the toner image to recording paper P
Is pressed again by the blade contacting / separating mechanism in the cleaning device 44 to clean its surface. At the time of repeat printing, the image formation on the photoreceptor 21 is performed after the fourth color image process for the first sheet, and proceeds to the second color image process at a predetermined timing. Further, the intermediate transfer belt 37 performs a primary transfer of the second black toner image to the surface area cleaned by the cleaning device 44, following the batch transfer process of the first four-color superimposed image onto recording paper. Is done. Thereafter, the same operation as the first sheet is performed as described above. The above is the description of the print mode for obtaining four full colors of A4 size horizontal feed. In the case of the three-color print mode or the two-color print mode, the same operation as described above is performed for the designated color and the number of times. Will be performed. Further, in the case of the single-color printing mode, until the predetermined number of sheets is completed, only the developing device of the predetermined color of the rotary developing device 31 is in the developing operation state, that is, the developing device of the predetermined color is in the developing position state.
The printing operation is continuously performed with the 4th flade pressed against the belt.

FIG. 2 is a block diagram showing an example of an embodiment in which the color image forming apparatus according to the present invention is applied to a color laser printer 100 as shown in FIG.
2, the color laser printer 100 includes paper feed trays 1a to 1d, paper type setting unit 2, image determination unit 3, paper type selection unit 4, paper supply unit 5, operation panel unit 6, storage unit 7, image processing It has a unit 8, a writing unit 9, a CPU 10, a ROM / RAM 11, and an external connection unit 12, and each of the units 2 to 12 is interconnected via a bus line. The paper feed unit 5 is provided with the paper feed roller 5.
1 to 54 and their driving mechanisms.
Denotes the writing optical unit 20, the photoconductor 21, the rotary developing device 31, the intermediate transfer belt 37, and the paper transport belt 4.
5, a fixing device 46, and the like. Here, a color laser printer is selected as an example of the color image forming apparatus, but the outline of the configuration and operation of the main part is the same in other color image forming apparatuses such as a color copier, a color printer of another system, and a color facsimile. is there.

The color laser printer 100 receives image information to be printed and information on setting conditions such as recording paper size from an external device 14 such as a personal computer. On the side of the color laser printer 100, the external device 1 is connected through an external connection unit 12 which functions as an interface or the like.
4 and stores the information at a predetermined position in the storage unit 7. The image information of the external device 14 stored in the storage unit 7 is
The image is processed by the image processing unit 8 in a form desired to be printed for each page,
It is stored in the storage unit 7 again. In the case of a color image, information is processed and stored for each of black, cyan, magenta, and yellow.

The information as to whether the image to be printed is to be processed as a monochrome image or a color image is stored in the external device 1.
4 is known for each page, and is sent to the color laser printer 100 prior to the printing process. The information is transmitted to the image determination unit 3 via the external connection unit 12 and the CPU 10. When printing in color, command information may be transmitted prior to image data to be printed, or RGB and CMY color information data may be transmitted in image data to be printed. Information on color image formation in that case is transmitted to the image determination unit 3 via the CPU 10. In the case of a color copying machine, a reading method, that is, a monochrome reading or a color reading, is selected by switches (not shown) of the operation panel unit 6.
The information on the selected reading method is stored in the image determination unit 3.
The image determination unit 3 determines that the image to be printed is for monochrome image formation when the image is read in black and white, and is determined for color image formation when the image is read in color.

On the other hand, in the paper type setting section 2, information on paper types stored in the respective paper feed trays 1a to 1d is set in advance. Then, the paper type selection unit 4 outputs the image determination unit 3
If the image to be printed next is a black-and-white image, the paper feed tray 1 to which plain paper is delivered is selected, and if the image is a color image, For example, the paper feed tray 1 to which the recording paper dedicated to color is delivered is selected. When the paper feed tray 1 is selected by the paper type selection unit 4, the recording paper in the paper feed tray 1 is transported to the registration roller pair 55 by the operation of the paper feed unit 5 and is made to stand by. Then, according to the writing timing,
The recording paper is sent to a writing position, and an image is written by the writing unit 9.

As shown in FIG. 3, each paper feed tray 1a to 1
Each of d has a paper type setting dial 15. The paper type setting dial 15 is provided with a symbol corresponding to the paper type of the recording paper.
The dial position of the paper type setting dial 15 can be changed in accordance with the paper type. In the example of FIG. 3, the paper type is selected by matching the symbol of the paper type setting dial 15 with the dial setting position mark 19 attached to the upper cover 17 of the paper feed tray 1. A set position detecting element 16 such as a magnet is embedded in the dial upper surface of the paper type setting dial 15, and the position of the set position detecting element 16 is set by mounting the paper feed tray 1 on the main body. Is detected, and information on the paper type delivered for each paper feed tray 1 is set in the paper type setting unit 2. The information of the paper type set in the paper type setting unit 2 can be easily recognized from the CPU 10 or the external device 14 via the bus line.

The color laser printer 100 includes:
An operation panel unit 6 in which display lamps and switches are collectively arranged is provided, and information setting corresponding to the type of recording paper stored in the paper feed tray 1 can be performed from the operation panel unit 6. I have. That is, although not shown, the paper type setting unit 2 is provided with a paper type storage unit that can set the paper type of the recording paper corresponding to the plurality of paper feed trays 1. The contents of the paper type storage unit can be rewritten by operating switches (not shown) provided on the operation panel unit 6. That is, when an operation for selecting a paper type is performed on the operation panel unit 6, a signal corresponding to the operation is transmitted to the paper type setting unit 2 via the bus line, and the paper type information is stored in the paper type storage unit. Note that R is used as a paper type storage unit.
A part of the RAM of the OM / RAM 11 may be allocated.

Further, based on the result determined by the image determining unit 3, the paper type selecting unit 4 selects the paper feed tray 1 to which plain paper is delivered if the next image to be printed is a black and white image. Then, the paper feed tray 1 to which the recording paper dedicated to the color is delivered is selected. However, if it is determined that the recording paper of the desired paper type does not exist in any of the paper feed trays 1, the display lamp of the display unit 6a is turned on to inform that the recording paper of the optimal paper type cannot be selected. Inform. In FIG. 2, the display unit 6a is shown as being inside the operation panel unit 6, but may be anywhere. Also, a paper type selection unit 4
When the recording paper of the optimum paper type cannot be selected based on the result determined by the image determining unit 3, one of the paper feeding trays is set by the tray designating unit 6b to the paper feeding tray 1 for image formation.
Can be specified. Therefore, at the time of image formation, the recording paper stored in the paper feed tray 1 designated by the tray designation unit 6b is conveyed to the registration roller pair 55 by the paper supply unit 5, and when the writing timing is matched, the writing position is changed. And the writing unit 9 writes the image. In FIG. 2, the tray designation section 6b is shown as being inside the operation panel section 6, but may be located anywhere. The CPU 10 is a microprocessor, and performs control of transmission and reception of signals of each unit via a bus line, timing adjustment, error monitoring, and the like. The ROM / RAM 11 is mainly used as a storage location for programs of the CPU 10 and a storage location for calculation results of the CPU 10.

In FIG. 2, the image judging section 3, the paper type selecting section 4 and the like are provided separately from the CPU 10.
Copy the program for the image determination unit or the program for the paper type selection unit stored in the ROM of the ROM / RAM 11 to the CP
The functions of the image determination unit 3 and the paper type selection unit 4 can be performed instead by the execution of U10. Also,
As shown in FIG. 2, when the color laser printer 100 is connected to an external device 14 such as a computer, a part and all of the functions of various switches of the operation panel unit 6 and the tray designation unit 6b are transferred to the external device 14. It is also possible to use a display attached to the external device 14 instead of the touch switch on the display attached to the external device 14 or a part and all of the display functions performed by the display unit 6a. Also,
In the above description, if it is determined that the recording paper of the desired paper type is not present in any of the paper feed trays 1, the operation panel unit 6 or the tray designating unit 6b in the color laser printer 100 specifies the paper feed tray. One of these is designated as the image forming paper feed tray 1 to form an image. However, when the color laser printer 100 is connected to the external device 14, the operation panel unit 6 or the tray designating unit It is also possible to perform image formation by designating the paper feed tray 1 by an instruction from the external device 14 instead of 6b. In addition, the external device 14
Can obtain the information of the paper type already set in the paper type setting unit 2 via the bus line and the external connection unit 12,
It is possible to designate in advance the paper feed tray 1 to which the recording paper suitable for the image to be printed is a monochrome image or a color image.

[0021]

As described above, according to the first aspect of the present invention, if the image to be formed is a black-and-white image, a plain paper feed tray is selected. The most suitable recording paper for the image is automatically selected, as in the case of, so that expensive color-specific recording paper is unnecessary when forming a monochrome image, or plain paper is used when forming a color image. It is possible to prevent the problem that the image quality is deteriorated by using. Claim 2
According to the invention described in (1), in addition to the effect of the first aspect, the paper type can be automatically set by selecting the paper type setting dial while looking at the recording paper stored in the paper supply tray. Even if the paper type is moved to another paper feeding place, it can be used without changing the paper type setting, so that the paper type setting and selection can be performed easily and accurately. According to the third aspect of the invention, in addition to the effect of the first aspect, since the paper type can be set by input from the operation panel unit, the setting and change of the paper type can be easily performed from the operation panel means. And operability is improved. According to the fourth aspect of the present invention, in addition to the effects of the first, second, and third aspects, when the recording paper of the optimum paper type cannot be selected from the paper feed tray by the paper type selection means, the selection is made. By providing a display means for displaying the impossibility, the user can immediately know that the operation has become abnormal by looking at the display contents of the display means, and replace the recording paper with an optimum recording paper or perform image formation. Can be taken immediately, such as canceling the operation, so that unnecessary waiting time can be eliminated and operability can be further improved. According to the fifth aspect of the invention, in addition to the effects of the first, second, third, and fourth aspects, even when the recording paper of the optimum paper type is out of paper, another stored paper type is used. It is possible to form a black-and-white image on recording paper dedicated to color at the expense of cost, or to form a color image on plain paper at the expense of image quality. The forming operation can be continued.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an internal structure of a color laser printer as one type of a color image forming apparatus to which the present invention is applied.

FIG. 2 is a block diagram illustrating an example of an embodiment of a color image forming apparatus according to the present invention.

FIG. 3 is a perspective view illustrating a form example of a sheet feeding tray of the color image forming apparatus according to the present invention.

[Explanation of symbols]

1 paper feed tray, 2 paper type setting section, 3 image judgment section, 4
Paper type selection unit, 5 paper supply unit, 6 operation panel unit, 7 storage unit, 8 image processing unit, 9 writing unit, 10 CPU, 1
1 ROM / RAM, 12 external connection unit, 100 color laser printer, 14 external device, 15 paper type setting dial, 20 writing optical unit, 21 photoreceptor, 31 rotary developing device, 37 intermediate transfer belt, 6
a display unit, 6b tray designation unit, 101 image forming unit, 102 paper feeding unit.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI G03G 15/01 G03G 15/01 N

Claims (5)

[Claims] 1. A color image forming apparatus having a function of forming black and white and color images, a paper type setting means for setting a plurality of paper feed trays and a paper type of recording paper stored in the paper feed trays. Image determination means for determining whether the image to be formed is a black-and-white image or a color image; and recording paper of an optimum paper type is stored in the paper feed tray in accordance with the determination result of the image determination means. And a paper type selecting means for selecting a paper feed tray. 2. The color image forming apparatus according to claim 1, wherein the paper type setting unit performs the setting based on a setting state of a paper type setting dial attached to the paper feed tray. 3. The apparatus according to claim 1, wherein said paper type setting means performs the setting in accordance with an input from an operation panel means.
3. The color image forming apparatus according to 1. 4. When the paper type selection means cannot select a recording paper of an optimum paper type from the paper feed tray, a display means for displaying that the paper type cannot be selected is provided. The color image forming apparatus according to claim 1. 5. A paper feed tray for using one of the paper feed trays for image formation when the optimum paper type cannot be selected from the paper feed tray by the paper type selection means. 5. The color image forming apparatus according to claim 1, further comprising a tray designating means for designating the color image.