JP2660410B2 - Image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention forms an electrostatic latent image on an image carrier, and visualizes the electrostatic latent image as a toner image by a developing device opposed to the image carrier. To an image forming method. 2. Description of the Related Art In an image forming method of the above type employed in an image forming apparatus such as an electronic copying machine, a printer or a facsimile, an image forming process condition of a toner image formed on an image carrier is adjusted and controlled. In order to improve image quality, a check mode operation is performed in which a test pattern image is formed on an image carrier and the amount of toner adhered thereto is detected. For example, when a two-component developer having a toner and a carrier is used in a developing device for forming a toner image on an image carrier, the amount of toner attached to the test pattern image is detected to detect the amount of toner in the developer. The density is detected, and when the density is below a predetermined range, toner is replenished into the developer to prevent image quality deterioration due to a decrease in toner density.
Alternatively, depending on the amount of toner adhered to the test pattern image, the amount of charge on the image carrier and, if the image carrier is a photoconductor, the amount of exposure to the photoconductor are adjusted so that an appropriate image can be obtained. ing. As described above, the test pattern image detection is performed for various purposes, and the amount of toner adhered to the test pattern image formed on the image carrier is, for example, the toner concentration of the developer or the amount of toner adhered to the image carrier. Not only charge or exposure amount,
Since it also varies depending on other factors, for example, the characteristics of the image carrier, the amount of developing bias, the amount of toner charge, and the like, the amount of toner attached to the test pattern image is detected, and based on this, specific image forming process conditions (for example, toner density ) Alone may not provide a high quality toner image. Such a point is also described in detail in Japanese Patent Application Laid-Open No. 58-60758. Further, the image quality may be deteriorated based on erroneous detection in which the detection of the toner adhesion amount of the test pattern image is not performed correctly. For example, when the position of the test pattern image formed on the image carrier is shifted for some reason, the detecting means detects the amount of toner attached to the portion including the background portion of the image carrier, In some cases, an accurate toner adhesion amount cannot be detected. Alternatively, an erroneous detection may occur due to an abnormality in the detection means itself or its control system. In such a case, for example, a situation occurs in which the toner is replenished in the developer even though the toner concentration of the developer is appropriate. OBJECTS OF THE INVENTION An object of the present invention is to provide an image forming method of the type described at the beginning, which can easily deal with various problems as exemplified above. In order to achieve the above object, the present invention provides an image forming method of the type described at the beginning, wherein a test pattern latent image is formed on an image carrier, and the test pattern latent image can be used as a test pattern image by the developing device. The test pattern image is detected by a detection unit, and the first test pattern image is not transferred to a transfer material.
In the check mode, a test pattern latent image is formed on the image carrier, and the test pattern latent image is visualized as a test pattern image by the developing device under image forming conditions at the time of forming the toner image. And a second check mode for transferring the test pattern image onto a transfer material. Embodiment Hereinafter, an embodiment in which the image forming method according to the present invention is applied to an electronic copying machine will be described. In FIG. 1, when a print key (not shown) is pressed, a drum-shaped photosensitive member 1 as an example of an image carrier is driven to rotate in a direction of an arrow by a main motor (not shown) via a suitable rotation transmitting means. Accordingly, the surface is uniformly charged by the charging charger 2. On the other hand, after pressing the print key, the optical scanning systems 3 and 4 move in the directions of the arrows, and at this time, the document O on the transparent document table 6 illuminated by the light source 5 is optically moved. (The original table 6 can be moved and scanned.) The scanning light image at this time is image-formed and projected on the photoconductor 1 via the mirrors 7 to 9, the lens 10, and the mirror 11. By such slit exposure, an electrostatic latent image corresponding to the document image is formed on the photoconductor 1. This electrostatic latent image is visualized as a toner image by the developing device 13 opposed to the photoconductor 1. Developing device of this example
In the case 13, a two-component developer having a carrier and a toner is contained in the developer case 30, and when the amount of the toner is insufficient, the toner is supplied from the toner container 31 to the toner supply roller 15 as described later. Is replenished. The developer replenished with the toner is pumped up while being stirred by the pumping roller 16, and the developing roller 17 to which a developing bias of a predetermined polarity is applied by the bias power supply 18.
Supplied to By this supply, the toner of the developer carried on the peripheral surface of the developing roller is electrostatically attached to the photoconductor 1, and the electrostatic latent image is visualized as a toner image. As described above, according to the image forming method of the present embodiment, an electrostatic latent image is formed on an image carrier made of the photoreceptor 1, and the electrostatic latent image is formed into a toner by the developing device 13 opposed to the image carrier. It is intended to be visualized as an image. A copy image is obtained by forming toner images corresponding to images of originals of various sizes on the photoconductor 1. The toner image is transferred by a transfer charger 19 to a transfer paper S fed at a timing by a paper feed roller 14, and thereafter the transfer paper is separated from a photoconductor by a separation charger 20, and a fixing device (not shown) Proceed to.
On the other hand, the residual toner on the surface of the photoreceptor is removed by the cleaning device 22, and the residual charge is removed by the charge removing means 23. Here, a reference pattern P having a predetermined reflectance is provided outside the document placement area of the document table 6, for example, a density
It consists of a 1.80 black pattern. As described above, the original O is illuminated and scanned by the movement of the optical scanning systems 3 and 4, but at this time, prior to the illumination scan of the original,
The reference pattern P is illuminated and scanned, and the scanning light images of the two are image-formed and projected on the photosensitive member 1 via the mirrors 7 to 9, the lens 10, and the mirror 11, respectively, to form a test pattern latent image. The test pattern latent image thus formed and the electrostatic latent image corresponding to the document are sequentially formed on the photoconductor, and the test pattern latent image is also visualized as a test pattern image by the developing device 13. Note that portions other than the reference pattern and the electrostatic latent image corresponding to the document are neutralized by the erase lamp 24 as described later. That is, the erase is performed. On the downstream side of the developing device 13, a photo sensor 26 which is an example of a detection unit for detecting the amount of toner attached to the test pattern image formed on the photoconductor 1 is provided at a portion facing the photoconductor 1. ing. Such a photo sensor 26
Thus, the density of the test pattern image with respect to the reference pattern P, that is, the toner adhesion amount is detected. In the figure, a CPU 27 determines whether or not to supply toner based on an output signal of the photo sensor 26 based on the detected density. If it is determined that the amount of toner adhered to the test pattern image is equal to or less than the predetermined amount, and thus it is determined that toner should be supplied, the drive unit 28 is operated to rotate the toner supply roller 15 and the toner in the toner container 31 is To the developer case 30. In this way, the toner concentration in the developer in the developer case 30 is always set to a value within a predetermined range,
It is possible to maintain a high quality toner image formed thereon. When detecting the toner end of the toner container 31, the CPU 27 causes the display 29 of the operation unit to display the toner end. The detection of the amount of toner attached to the test pattern image by the photo sensor 26 may be performed for each copy operation. For example, the detection may be performed only once for every ten copy operations. If no, the electrostatic latent image of the reference pattern is erased by the erase lamp 24 so that a test pattern image is not formed. Further, when the developing device 13 is configured so that the developer can be replaced with a different color, the CPU 27 determines whether or not to supply toner based on the output signal of the photo sensor 26 between the black toner and the color toner. The determination can be made based on the toner density level, and the rotation of the supply roller 15 can be turned on and off. In this case, a signal corresponding to the color of the developer is output depending on the difference of the developing device attached to the copying machine body, and it is determined whether the attached developing device is black or color. it can. As described above, according to the image forming method of the present embodiment, a test pattern latent image is formed on an image carrier made of the photoreceptor 1, and the test pattern latent image is visualized as a test pattern image by the developing device 13. A check mode is provided for detecting the amount of toner adhered to the test pattern image by the detecting means. In this check mode, the test pattern image is not transferred to the transfer material. That is, the transfer paper S is supplied to the photoconductor 1 by the paper feed roller 14 at a timing matching only with the toner image formed corresponding to the original image on the photoconductor 1,
Only this toner image is transferred to the transfer paper S. Hereinafter, such a check mode is referred to as a first check mode. Here, in the first check mode, the photosensitive member 1
As described above, simply detecting the toner adhesion amount of the above test pattern image and adjusting and controlling the toner concentration in the developer causes the test pattern image to be removed due to factors other than the toner concentration in the developer. It is impossible to cope with the case where the amount of toner adhesion increases or decreases. For example, even if the toner concentration of the developer is at an appropriate value, the toner adhesion amount may be out of the appropriate value based on the deterioration of the function of the charging charger or the like. It is not possible to keep the quality of the toner image high by only such control. The same may occur due to an abnormality of the photo sensor 26 or the like. Therefore, in the image forming method of this embodiment, the first
In addition to the check mode described above, a test pattern latent image is formed on the image carrier composed of the photoreceptor 1 and the test pattern latent image is tested by the developing device 13 under the above-described image forming conditions for forming a toner image. A second check mode is provided for visualizing a pattern image and transferring the test pattern image to a transfer material. Specific examples are as follows. As shown in FIG. 1, a CPU 27 has a second check mode for transferring a test pattern image to a transfer material, and a toner image formed on an image carrier is transferred to transfer paper. A mode changeover switch 32, which is an example of a changeover means for selectively switching one of the first and second check modes, is connected. Such a switch can be appropriately switched on, for example, an operation unit. When the second check mode is selected, the test pattern is provided on the photosensitive member 1 as described above. A latent image is formed, and the latent image of the test pattern is visualized as a test pattern image by the developing device 13, and the test pattern image is transferred to a transfer sheet as an example of a transfer material. In the second check mode, the developing device 13 visualizes the latent image of the test pattern as a test pattern image under the above-described image forming conditions for forming the toner image. The image forming conditions are set the same as in the case of normal toner image formation. However, in the present embodiment, the transfer timing of the transfer paper by the paper feed roller 14 can be changed. That is, in this embodiment, since the test pattern image on the photosensitive member 1 is configured to be transferred to the transfer paper S, the transfer paper S is sent earlier than when a normal toner image is formed. It has become. In this manner, the test pattern image is transferred onto the transfer paper, and this test pattern image is also fixed on the transfer paper S when the transfer paper S passes through the above-described fixing device. The test pattern image on the transfer paper obtained in this way is visually checked by, for example, a service person, so that it can be determined whether or not the test pattern image is formed normally. For example, if uneven charging or the like has occurred, the density of the test pattern image becomes non-uniform in a band shape, and it is determined that "uneven charging has occurred", and the charger and the like are checked. Also, if the optical scanning system causes a speed change due to a change in driving load or the like, the position of the test pattern image on the photoconductor 1 shifts, and the amount of toner adhesion in a low density portion is detected. Although it may not be possible to accurately detect the amount of adhered toner, in this embodiment, if the transfer paper printed out can be visually recognized, the position deviation of the test pattern image can be grasped.
By comparing with the detection amount by 26, it is possible to know the abnormality in the driving of the optical scanning system. Such a function cannot be achieved at all by a technique that only detects the toner adhesion amount of the test pattern image on the photoconductor. In addition, a test pattern image of a printed out transfer paper is compared with a test pattern image of a target toner adhesion amount on the photoreceptor 1 (for example, 1.0 to 1.2 in image density transferred and fixed on the transfer paper S). Is extremely light or dark, it is possible to judge that the function of detecting the amount of toner adhered by the photo sensor 26 or the control system thereof is abnormal. Can be performed, and toner supply and other image forming process conditions can be appropriately set. In the second check mode, the test pattern latent image formed on the photoconductor 1 is visualized as a test pattern image by the developing device 13 under the normal toner image forming conditions. Thus, the control mode of the control device of the image forming apparatus, in particular, the control mode of the control device of the developing device can be simplified. In addition, since the test pattern image transferred onto the transfer material is formed under image forming conditions when forming a normal toner image, the state of the copying machine itself at the time of the check appears as the image quality of the test pattern image. Therefore, by checking the test pattern image, the situation of the copying machine at that time can be immediately and accurately grasped, and when there is an abnormality, the situation can be promptly dealt with. . If the switch 32 is switched after executing the second check mode, it is possible to switch to the first check mode very easily and immediately. Recently, in this type of copying machine, there is a copying machine in which the toner adhesion amount of the test pattern image on the photoconductor 1 read by the photo sensor 26 can be displayed on an operation panel by operating a changeover switch (not shown). However, it is more effective to perform the above-described determination while viewing both the display and the test pattern image printed on the transfer paper. That is, the visual judgment by the serviceman,
It is possible to relatively compare mechanical judgment and mechanical determination, which is very useful for appropriately determining the presence or absence of an abnormality in the detection system, and properly determining image forming process conditions such as toner concentration conditions and charging conditions. When the current of the transfer charger 19 and the separation charger 20 is changed or the separation operation is performed at the same timing as the sheet feeding operation of the sheet feeding roller 14, the change of the sheet feeding timing is performed in the second check mode. The timing for applying the transfer voltage or the separation voltage is changed and adjusted accordingly. In addition, in the second check mode, a toner image of a document image may be transferred to the transfer paper S together with the test pattern image, or this test image may be exclusively transferred to the transfer paper S without transferring the toner image. It may be transferred to S. Next, in order to understand the present invention, a detailed operation of the above-described embodiment will be described with reference to a timing chart shown in FIG. Regarding the operation timing of the erase lamp 24 in the check mode of FIG. 1, first, the entire surface (full width) of the photoconductor 1 is erased until the optical image of the reference pattern is projected on the photoconductor. When an area on the photoconductor where a test pattern latent image corresponding to the reference pattern is to be formed comes to the erase lamp 24, for example, a surrounding area other than the area is erased by the erase lamp. (Pattern erase in FIG. 2). Next, the entire area between the area and the area where an electrostatic latent image on the document is to be formed is erased by the erase lamp 24. When the area where the electrostatic latent image for the original is to be formed comes to the erase lamp 24, the designated original size, transfer paper size,
The area other than the area corresponding to the specified size by editing or the like is erased (erase by document size in FIG. 2). As for the developing bias, a developing bias (pattern bias) suitable for the development is applied to the developing roller 17 in accordance with the timing at which the test pattern latent image corresponding to the reference pattern reaches the developing roller 17. Also, when developing an electrostatic latent image corresponding to a document, a manually or automatically set developing bias is applied to a developing roller.
Applied to 17 (setting bias). On the other hand, the transfer paper S is sent from the paper feed roller 14 at a timing so that the leading edge of the toner image with respect to the document and the leading edge of the transfer paper meet at the transfer portion at an opportunity. On the other hand, when the second check mode is selected, as shown at the bottom of FIG. 2, the paper feed timing of the paper feed roller is advanced as compared with the first check mode, and as described above, Is transferred to the transfer paper. Other operations will be apparent with reference to FIG. In the above-described embodiments, the toner density in the developer is adjusted and controlled based on the density detection result of the test pattern image. However, for other appropriate purposes,
It is also possible to form a test pattern image on the image carrier and transfer this to a transfer material. For example, when the density detection information of the test pattern image is fed back to the charging means and the exposure means to control image forming process conditions such as charging conditions and exposure conditions. Further, in order to detect the amount of toner attached to the test pattern image, an optical sensor such as the photo sensor 26 or a sensor which detects magnetically can be used. Further, various methods other than providing a reference pattern on the document table 6 and obtaining a test pattern image as in the illustrated embodiment can be adopted. The present invention is also applicable to various image forming apparatuses other than the illustrated type of electronic copying machine, for example, an apparatus having an image carrier made of a dielectric material. Advantageous Effects According to the present invention, even if an abnormality occurs in the image forming apparatus, the abnormality can be correctly grasped and an appropriate toner image can be formed on the image carrier. Further, in the second check mode, the test pattern latent image formed on the image carrier is visualized as a test pattern image by the developing device under a normal toner image forming condition. The control mode of the control device of the image forming apparatus, in particular, the control mode of the control device of the developing device can be simplified.
In addition, since the test pattern image transferred onto the transfer material is formed under image forming conditions for forming a normal toner image, the state itself of the image forming apparatus at the time of the check appears as the image quality of the test pattern image. . Therefore, by checking the test pattern image, the situation of the image forming apparatus at that time can be grasped immediately and accurately, and when there is an abnormality, it is possible to quickly cope with the situation. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a copying apparatus, and FIG. 2 is a timing chart corresponding to the embodiment. 13 Developing device

Claims (1)

(57) [Claims] In an image forming method of forming an electrostatic latent image on an image carrier and visualizing the electrostatic latent image as a toner image by a developing device opposed to the image carrier, a test pattern is formed on the image carrier. Forming a latent image, visualizing the test pattern latent image as a test pattern image by the developing device,
A first check mode in which the toner adhering amount of the test pattern image is detected by a detection unit and the test pattern image is not transferred to a transfer material; and a test pattern latent image is formed on the image carrier, and the test pattern latent image is formed. An image is formed by the developing device under image forming conditions at the time of forming the toner image.
An image forming method comprising: a second check mode for visualizing a test pattern image and transferring the test pattern image to a transfer material.