JPH01213675A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention generally relates to an image forming apparatus, and particularly relates to an image forming apparatus such as a multicolor electrophotographic image forming apparatus or a laser beam printer in which a plurality of image forming units are arranged. In this specification, it is particularly applicable to a color image forming apparatus that obtains an image by overlapping transfer onto a transfer material such as a transfer paper conveyed by a transfer material conveying means in a plurality of image forming units. will explain a color image forming apparatus.

Generally, a color image is provided with a transfer material conveying device that conveys a transfer material such as an image carrier sheet, i.e., transfer paper, supplied from the outside, to an image forming section by a conveyance means such as a conveyance belt. The forming apparatus includes a plurality of developing units each containing a different type of color developer.
One type has a rotating body, an image bearing member, that is, a photosensitive drum, and a transfer material holder, that is, a transfer drum, which are respectively disposed in the vicinity of the rotating body, and a type that has a developer of each color. There is also a type in which image forming units are arranged side by side.

As an example of the latter type of image forming apparatus, a color printer using Carlson electrophotography for forming a latent image is taken as an example, and its configuration is as shown in FIG. The overall configuration of the color image forming apparatus illustrated in FIG. 5 includes a conveying means 8 for conveying a transfer material 6 such as a transfer paper, a fixing section 7, and the direction of the arrow in FIG. Four image forming apparatuses are installed in parallel along the
c, Pd. The image forming units Pa and Pb
, Pc, and Pd are dedicated photosensitive drums 1a, lb, and l, respectively.
c, lcl, and these photoreceptor drums 1a, 1b, lc,
Dedicated latent image forming sections 2a arranged around the ld.
, 2b, 2C12d, developing section 3a, 3b, 3c, 3d,
Transfer parts 4a, 4b, 4c, 4d and cleaning means 5
It is composed of a, 5b, 5c, and 5d.

In the above-described configuration, first, a latent image of the yellow component color of the original image is formed on the photoreceptor drum la by a known electrophotographic method in the latent image forming section 2a of the first image forming unit Pa, and then, A visible image is formed by a developer containing yellow toner in the developing section 3a, and the formed yellow toner image is transferred onto the transfer material 6 by the transfer section 4a.

On the other hand, while the yellow image described above is being transferred to the transfer material 6 by the transfer unit 4a, the second image form
Then, a latent image of the magenta component color of the original image is formed on the photoreceptor drum lb by the latent image forming section 2b, and then a toner image with magenta toner is obtained in the developing section 3b. When the transfer material 6 on which the transfer has been completed is carried into the transfer section 4b of the second image forming unit (Pb), the magenta toner image is transferred to a predetermined position on the transfer material 6.

Thereafter, image formation for cyan and black colors is performed in the same manner as described above, and when the overlapping of the four color toner images on the transfer material 6 is completed, the transfer material 6 is fixed in the fixing section 7, A multicolor image is obtained on the transfer material 6. Each of the photosensitive drums la, lb, lc, and ld after the transfer is
The remaining toner is removed by the cleaning means 5a, 5b, 5c, and 5d, respectively, in preparation for the next latent image formation to be performed subsequently.

By the way, in conventional image forming apparatuses having the above-mentioned configuration, in order to prevent transfer position deviation and image deviation of toner images during so-called multiple transfer, each image forming apparatus ) The supply timing of the transfer material 6 to Pa, Pb, Pc, Pd and the respective image forming units Pa, Pb, Pc,
Since it is necessary to adjust the output timing of the drive command signal for causing Pd to execute the image forming process, the transfer material 6 is placed on the starting end side of the transfer material conveyance direction of each of the image forming units Pa, Pb, Pc, and Pd. A detection means is required to detect the tip of the sensor and output a predetermined detection signal. Further, the process of transferring the visible images formed on the respective photoreceptor drums la, 1b, 1c, and ld to the transfer material 6 performed in the photoreceptor drums 1a, 1b, 1c, and ld, and the respective photoreceptor drums. In the process of separating the transfer material 6 from la, 1b, and IC 11d, a jam may occur in the transfer material 6, so a means for detecting whether or not a jam has occurred in the transfer material 6 is also required. It's coming. Furthermore, the amount of charge of the developer varies greatly depending on the environmental conditions in which the image forming apparatus is installed, especially the atmospheric humidity of the image forming apparatus, resulting in a problem that the image density fluctuates. It is necessary to control fluctuations in characteristics, and as a means to appropriately control such fluctuations in humidity-development characteristics, a patch with a constant density is developed, the developed density of the patch is detected, and a method is developed based on the detection result. It is also necessary to install a device for adjusting developing conditions and latent image forming conditions.

However, if the above-mentioned means and devices are to be installed as they are in an image forming apparatus having the configuration shown in FIG.
The number of detectors must also increase, which inevitably increases the number of parts and increases costs.Moreover, the frequency of detector adjustment increases, which worsens maintenance and reduces reliability. There was a problem that this could also be a factor.

Therefore, the present invention was devised to solve the above-mentioned problems, and its purpose is to provide a transfer material tip that has a small number of parts, is low cost, easy to maintain, and has high reliability. An object of the present invention is to provide an image forming apparatus that can perform part detection, jam detection, and development density detection.

The objective described in E above is achieved by the image forming apparatus according to the present invention. To summarize, the present invention includes a plurality of image forming sections provided, and a transfer material conveying means for placing and conveying a transfer material for transferring a visible image formed in the image forming section. In the image forming apparatus equipped with the above-mentioned image forming apparatus, optical detection means are provided which are positioned at the starting end side in the transfer material conveyance direction and at the end end side in the transfer material conveyance direction of each of the image forming sections, and an output signal from the optical detection means is provided. detects the leading end of the transfer material conveyed by the transfer material conveyance means and/or detects whether or not a jam has occurred in the transfer material, and also detects whether or not a jam has occurred in the transfer material, and furthermore, This image forming apparatus is characterized in that it is provided with a control means for detecting the degree of reflection wetness of a visible image transferred onto the means.

Also muj The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a diagram showing a color image forming apparatus according to an embodiment of the present invention. The image forming apparatus is embodied in an image forming apparatus, and the overall structure thereof is the same. That is, in FIG. 3, a transfer material outlet 14 and a fixing device 7 are arranged on the left side of the image forming apparatus main body 10 (hereinafter simply referred to as "apparatus main body 10") in FIG. 3, and facing the exit 14. On the other hand, a paper feed mechanism 13 is disposed on the right side of the apparatus main body 1O in FIG. 3. The device main body lO
In the section from the paper feed mechanism 13 to the fixing device 7, one end is provided close to the paper feed mechanism 13, ie, the drive roller 11, and the other end is provided close to the fixing device 7. A transfer material conveying means, ie, a transfer material conveying belt 8 is provided, which is wound around a pulsating roller means, ie, an idler roller 12 provided at ing. Further, in the section from the drive roller 11 to the idler roller 12, image forming sections, that is, image forming units Pa, Pb, Pc, and Pd are arranged in order from the paper feed mechanism 13 side in close proximity to the transfer material conveying belt 8. It is set up.

The aforementioned transfer material conveying belt 8 is driven by a driven roller 11 in the direction of the arrow in FIG. It is conveyed sequentially to forming units Pa, Pb, Pc, and Pd. The paper feed mechanism 13 outputs a predetermined signal when it detects a paper feed guide 51 that guides the transfer material 6 inserted from the outside, a pair of registration rollers 80, and the leading edge of the transfer material 6 moving within the paper feed guide 51. The transfer material 6 is placed on the conveyor belt 8 from the drive roller 11 side. The fixing device 7 receives the transfer material 6 applied from the idler roller 12 side.
Then the image form J&:x-2y) P a, P
b, Pc, and Pd to fix the visible image transferred to the transfer material 6. The above-mentioned image forming units Pa, Pb, Pc, and Pd have substantially the same configuration, and each of the image forming units Pa, Pb, and Pc
, Pd are latent image carriers that are rotationally driven in the direction of the arrow in FIG.
c, ld, and chargers 15a, 15b, which are sequentially provided around the respective drums in the drum rotation direction.
15c, 1'5d, developing devices 3a, 3b, 3C13d, transfer dischargers 4a, 4b, 4C24d, cleaning means 5a, 5b, 5c, 5d, and the photosensitive drums la, l.
The laser beam scanners 16a, 16b, 16c, and 16d are provided above the laser beams b, lc, and 1d, respectively. The developer 3a stores yellow toner, the developer 3b stores magenta toner, the developer 3C stores cyan toner, and the developer 3d stores black toner. The laser beam scanners 16a, 16b
, 16c, 16d are semiconductor lasers, polygon mirrors,
It consists of an fθ lens, etc., and receives an input of an electrical digital pixel signal and directs a laser beam modulated in accordance with the signal between the chargers 15a, 15b, 15c, 15d and the developing devices 3a, 3b, 3C13d. The drum surface is exposed by scanning in the direction of the drum generatrix. The aforementioned laser beam scanner 16a receives a pixel signal corresponding to the yellow component image of the color image.
A pixel signal corresponding to the magenta component image is input to ab, a pixel signal corresponding to the cyan component image is input to the laser beam scanner 16c, and a pixel signal corresponding to the black component image is input to the laser beam scanner 16d. Ru. An attraction charger 59 and an attraction charger 62 are provided between the image forming unit (image forming unit), the paper feed mechanism 13 and the attraction charger 59 with the conveyor belt 8 in between. has been
The attraction chargers 59 and 62 perform corona discharge to ensure that the transfer material 6 supplied from the paper feed mechanism 13 is attracted to the conveyor belt 8. On the other hand, between the image forming unit) Pd and the fixing device 7, an idler roller 1
A static eliminator 61 is provided substantially directly above the transfer belt 2 , and an AC voltage is applied to the static eliminator 61 in order to separate the transfer material 6 that is attracted to the conveyor belt 8 . On the upstream side in the conveying direction of each of the above-mentioned image forming units) Pa, Pb, Pc, and Pd, there are optical detection means, that is, sensors 60a and 60, respectively.
b, 60C160d are disposed, and an optical detection means, that is, a sensor 60f is disposed downstream of the fixing device 7. Among the sensors described above, the sensors 60a, 60b,
60c and 60d detect when the leading edge of the transfer material 6 conveyed by the transfer material conveyance belt 8 passes, and control the respective image forming units Pa, Pb, and Pc.
, a control unit (not shown) which sends a signal to start the image forming process in Pd.
is configured to output to . Moreover, the sensor 60
e detects the leading edge of the transfer material 6 that has passed through the fixing device 7 and outputs a predetermined signal to the control means.

Now, when the sheet-shaped transfer material 6 is inserted as a transfer material onto the paper feed guide 51 of the paper feed mechanism 13, its leading edge is detected by the sensor 52.
The photosensitive drums la, 1b, and IC11d of the image forming units (Pa, Pb, Pc, Pdc7) start rotating using the signal output from the image forming unit as a start signal. The drive roller 11 is also driven at the same time, and the transfer material conveyance belt 8 starts to be driven in the direction of the arrow in FIG. When the transfer material 6 is guided by the paper feed guide 51 and placed on the transfer material conveyance belt 8, it is reliably attracted onto the transfer material conveyance belt 8 by corona discharge from the adsorption charger 59. . As the transfer material conveying belt 8 moves in the direction of the arrow in FIG.
When the light passes through the detection area 60d (F), image formation on each of the photosensitive drums 1a, 1b, and IC 11d starts sequentially. That is, the photosensitive drum 1a of the first image forming unit)Pa carries a yellow image, the second image forming unit)Pb carries a magenta image, the third image forming unit)Pc carries a cyan image, and the fourth image forming unit)Pc carries a cyan image. A black image is formed on each of the image forming units Pd shown in the figure.

The principle of image formation in each of the image forming units Pa, Pb, Pc, and Pd is already well known as the Carlson process, so its explanation will be omitted. As the transfer material conveyance belt 8 moves, the transfer material 6 passes sequentially under the photoreceptor drums 1a to 1d of the first to fourth image forming units/ ) P a to P d in the direction of the fixing device 7 . The transfer dischargers 4a, 4b, 4c, and 4d of each unit sequentially transfer each color onto the surface of the transfer material 6 in an overlapping manner to synthesize a color image.

When the transfer material 6 passes through the fourth image forming unit (Pd), the transfer material 6 is neutralized by a static eliminator 61 to which an alternating current voltage is applied, and is separated from the transfer material conveyance belt 8. The transfer material 6 separated from the transfer material conveying belt 8 enters a fixing device 7, where the image is fixed, and is then discharged from the outlet 14 to the outside of the apparatus main body 10, and along with the image is fixed to the fixing device 7. A predetermined signal is output from 6°F and one print cycle is completed.

Further, according to an embodiment of the present invention, the sensor 60a,
The signals output from each of 60b, 60c, 60d, and 60e are subjected to signal processing as described below to determine whether or not a jam (including skewed movement of the transfer material 6) has occurred in the transfer material 6. In addition, it is also possible to detect the development density of the patch pattern formed on the transfer material conveying belt 8.

The above-mentioned configuration will be explained in further detail with reference to FIG. 1st
For convenience of explanation, the figure shows the third r1! This is a configuration in which components other than the transfer material conveying belt 8, photosensitive drum la, developing section 3a, and transfer section 4a are removed from the configuration illustrated in J. In FIG. 1, the aforementioned sensors 60a and 60b have a structure in which an infrared LED (wavelength: 950 mm) and a light receiving section that receives reflected light from the infrared LED are assembled integrally. transfer material conveyance belt 8
In order to detect with high precision the leading edge of the transfer material 6 being conveyed by the sensor, a sensor is used to focus the light emitted from the infrared LED onto a portion of the transfer material 6 shown at 20 in FIG. A lens system is attached to the tip of the main body. The sensors 60a and 60b detect the leading edge of the transfer material 6 when the transfer material 6 is conveyed to the position indicated by the reference numeral 20 in FIG. 1 and the reflected light incident on the light receiving section changes. In this embodiment, the detection accuracy of the leading edge of the transfer material 6 by the sensors 60a and 60b is ±150 μm, and the distance between the transfer section 4a and the sensor 60a is equal to or smaller than the photoreceptor drum 1a. It is set so that the circumference is approximately equal to or larger than that of a wing.

The detection of the leading edge of the transfer material 6 by the sensors 60a and 60b is performed by subjecting the detection signals output from the sensors 60a and 60b to predetermined signal processing in a known signal processing circuit. This is done by outputting predetermined signals to the image forming units y)Pa and Pb.

Detection of whether or not a jam has occurred in the transfer material 6 by the sensors 60a and 60b is performed by a known second signal processing circuit different from the above-mentioned signal processing circuit. This is done by determining the time difference between the input timings of the signals from the sensors 60a and 60b. That is, the time difference value between the time when the signal from the sensor 60a is output to the second signal processing circuit and the time when the signal from the sensor 60b is output to the second signal processing circuit is set in advance. The second signal processing circuit determines that the second signal processing circuit substantially matches the reference time difference value (that is, the value obtained by dividing the distance between the sensor 60a and the sensor 60b by the speed of the transfer material conveying belt 8). On the other hand, when the first signal processing circuit determines that the above-mentioned time difference value is larger than the reference time difference value, it is determined that no jam has occurred in the transfer material 6. It is assumed that a jam occurred in the material 6.

Furthermore, the detection of the developed density of the patch pattern transferred from the photosensitive drum 1a onto the transfer material conveying belt 8 or onto the transfer material 6 by the sensor 60b is performed using a known method different from the first and second signal processing circuits. The third signal processing circuit of
This is done by subjecting the signal output from the sensor 60b to predetermined signal processing. That is, the third signal processing circuit stores in advance the output voltage (()) from the sensor 60b as shown in FIG.
It stores data indicating the relationship between the photocurrent gA) and the density of the yellow toner image of the patch pattern transferred onto the transfer material 6, and uses the value of the output signal from the sensor 60b and the data. , the development density of the patch pattern in the output signal is estimated, and feedback control is performed to ideal development conditions and latent image formation conditions in the output signal.0 Adopted in the image forming apparatus according to the present invention. The transfer material conveying belt 8 is the infrared LE
With respect to D, it can be regarded as substantially transparent, so even if a visible image of a patch pattern is formed on the transfer material conveying belt 8, the scattered light due to the visible image can be detected. For details of the feedback control, see, for example, Japanese Unexamined Patent Publications No. 55-12916 and Japanese Unexamined Patent Publication No. 55-1.
Please refer to the descriptions in Japanese Patent Application Laid-open No. 5185, Japanese Patent Application Laid-open No. 56-57049, etc. Also, the transfer of the patch pattern visible image on the transfer material conveying belt 8 is carried out immediately before the start of the image forming process or continuously. During the execution of the image forming process, the image forming process is performed at a location between the transfer material 6 and another transfer material, and the developed image of the patch pattern transferred onto the transfer material conveying belt 8 has a different density. After detection, it is cleaned by a belt cleaner (not shown) in preparation for the next image forming process.

The above-mentioned process is carried out in substantially the same manner for the image forming units Pb and Pc, and a jam of the transfer material 6 is also detected at the same time as the leading end of the transfer material 6 is detected for each image forming unit. In addition, the image form acid 2) Pd
, the leading edge of the transfer material 6 is detected by the sensor 60d, the jam detection of the transfer material 6 is performed by the sensor 60d and the sensor 60e, and the detection of the developed density of the patch pattern is performed by the sensor 60e. It is something that can be done. There is no problem in detecting the developed density of the patch pattern as described above using only the sensor 60e, and it is possible to detect the developed density of the patch pattern of all four colors of yellow, magenta, cyan, and black using only the sensor 60e. is possible.

FIG. 4 shows a color image forming apparatus according to another embodiment of the present invention, which is a color image forming apparatus according to another embodiment of the present invention illustrated in FIG. A color image forming apparatus according to an embodiment of the invention is an image forming apparatus according to the present embodiment in which a sensor 60a and a sensor 60b are installed above the transfer material conveyance belt 8, and the above-mentioned The difference is that jam detection of the transfer material 6, including detection of the leading edge of the transfer material 6, and development density detection of the patch pattern formed on the transfer material conveyance belt 8 are performed. The reason for this configuration is that when a non-transparent material is used for the transfer material conveyance belt 8, that is, when a material that has been treated to reduce the volume resistance of the belt 8 by dispersing carbon, for example, is used. Secondly, since the conveyor belt 8 is not transparent, the infrared LED light emitted from the infrared LEDs is absorbed by the conveyor belt 8, and this is to prevent a problem in which the prescribed detection cannot be performed. As the detection light source, it is also possible to use the laser beam for image exposure described above, and specifically, the laser beam scanners 16a and 16b described above
, 16c, and 16d are used to irradiate the transfer material conveying belt 8 with light outside the image scanning width of the laser beams by a mirror installed in the optical system.

In the embodiments of the present invention, a photoreceptor drum is used as the image carrier, but an insulated drum that forms a latent image using a multi-stylus or modulated ion flow may also be used. Alternatively, a belt-shaped image carrier may be used instead of the insulated drum. Furthermore, the present invention
The scope of application is not limited to color electrophotographic copying devices, but can also be applied to image forming devices that overlap a plurality of image patterns using one color toner.

As explained above, according to the present invention, the leading edge detection, jam detection, and development density of the transfer material can be performed with a small number of parts, low cost, good maintenance, and high reliability. An image forming apparatus capable of performing detection can be provided.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view showing the main parts of a color image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the image density and the detector output for reading patch density on the transfer material conveying belt of the color image forming apparatus according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing the overall configuration of a color image forming apparatus according to an embodiment of the present invention. FIG. 4 is a partial vertical sectional view showing the main parts of a color image forming apparatus according to another embodiment of the present invention. FIG. 5 is a longitudinal sectional view showing the configuration of an image forming apparatus according to the prior art. 6: Transfer material 8: Transfer material conveyance belts 61a, 60b, 80c, EiOd, He, 80f: Sensors Pa, Pb, Pc, Pd: Image forming apparatus 0.
5 1.0 1.5 2.0
2.5 Image density on transfer material Figure 3 Figure 4

Claims (1)

[Claims] 1) An image forming apparatus comprising a plurality of image forming sections arranged in parallel, and a transfer material conveying means for placing and conveying a transfer material for transferring a visible image formed by the image forming section. In this method, optical detection means are provided at the starting end side in the transfer material conveyance direction and the end end side in the transfer material conveyance direction of each of the image forming sections, and the output signal from the optical detection means detects the transfer material. In addition to detecting the leading edge of the transfer material conveyed by the conveyance means and/or detecting whether or not a jam has occurred in the transfer material, the image forming apparatus further detects the leading edge of the transfer material conveyed by the conveyance means, and further detects whether or not the transfer material is transferred from each image forming section onto the transfer material conveyance means. An image forming apparatus comprising: a control means for detecting the reflection density of a visible image.