JP2004020769A - Color image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color image forming device which secures both the responsiveness necessary for detecting patterns for resist correction and a dynamic range necessary for detecting the amounts of image forming substances in order to use in common a sensor for detecting the patterns for resist correction and a sensor for detecting the amounts of the image forming substances. <P>SOLUTION: The image forming device has an output control means for controlling electromagnetic wave output varied by the kinds of two or more patterns formed on a recording medium by using the image forming substances (toners). The control means performs the continuous output particularly in detecting the resist patterns and the intermittent output in detecting the density patterns. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color image forming apparatus such as a color copying machine or a color printer, and uses an image forming substance (optionally referred to as toner) to form one or more detection patterns on a recording medium (optionally referred to as recording paper). A color image forming apparatus capable of detecting a formed one, detecting a specific forming parameter of the image forming substance formed on a recording medium, and correcting a forming condition of the image forming substance, The present invention relates to a color image forming apparatus for improving detection accuracy of a specific image forming parameter in an image forming substance.
[0002]
[Prior art]
As a conventional color image forming apparatus, for example, a plurality of image forming units are arranged on a recording medium conveyance path along a horizontal direction, and the recording medium moving along the recording medium conveyance path sequentially from each of the image forming units. A so-called tandem type in which an image forming substance is transferred to form a color image on a recording medium is known.
[0003]
FIG. 4 shows an example of the internal configuration of a conventional tandem-type color image forming apparatus. The inside of the color image forming apparatus mainly includes an image forming unit 11, an LSU 13, an intermediate transfer unit 14, a recording medium storage unit 15, a transfer roller 17, a fixing unit 18, and a discharge unit 19. The image forming unit 11 includes a plurality of units (four units in FIG. 4) each storing an image forming substance having a partly different substance (for example, a coloring material). The image forming unit can form an image on a recording medium at a time. This is why it is called a tandem type.
[0004]
In this color image forming apparatus, first, a latent image is formed on the photoconductor 12 inside the image forming unit 11 by a laser beam emitted from the LSU 13, and then, for example, the latent image is stored inside the image forming unit 11. An image forming substance such as toner adheres to a latent image portion on the photoconductor 12.
[0005]
The image forming substance attached to the latent image portion is once transferred to the intermediate transfer unit 14, and then the recording medium supplied from the recording medium storage section 15 is discharged to the discharge section 19 through the recording medium transport path 16. At the contact point between the intermediate transfer unit 14 and the transfer roller 17, the image is retransferred to the recording medium. Thereafter, the recording medium to which the image forming substance has been transferred is subjected to a fixing process of the image forming substance by the fixing unit 18, and is discharged from the discharge unit 19.
[0006]
In a tandem type color image forming apparatus, since there are a plurality of image forming units, an image from each image forming unit due to a state of attachment to the main body and physical variation of components constituting the image forming unit itself. A formation position shift occurs. For example, if a material that is partially different from the materials constituting the image forming material stored in each image forming unit is, for example, a color material, the color shift occurs on the recording medium. Is perceived by human vision. Accordingly, it is necessary to detect a deviation of the image forming position of each image forming unit and to correct the deviation.
[0007]
A conventional tandem type color image forming apparatus usually has an intermediate transfer unit as shown in FIG. For this reason, the position where the image forming position shift is detected is on the surface of the intermediate transfer belt mounted on the intermediate transfer body unit.
[0008]
5 and 6 each show an example of the configuration of a detection system for detecting an image forming substance on the intermediate transfer belt. FIG. 5 shows a case where the image forming material is not placed on the intermediate transfer belt 21, and FIG. 6 shows a case where the image forming material is placed on the intermediate transfer belt 31. The detection system mainly includes intermediate transfer belts 21 and 31 and image forming substance detection sensors 22 and 32 such as, for example, reflection type photo sensors. The intermediate transfer belts 21 and 31 are transported in the transport directions of the intermediate transfer belts 25 and 35, respectively.
[0009]
The intermediate transfer belt is usually made of a material whose surface is as smooth as possible so that the image forming material remaining on the surface even after transfer to the recording medium can be easily removed. The mounting angles of the image forming substance detection sensors 22 and 32 have a specific angle θ with respect to the tangential direction of the intermediate transfer belts 21 and 31. Thus, when the image forming substance is not placed on the intermediate transfer belt 21 as shown in FIG. 5, for example, most of the detection beam such as infrared light emitted from the image forming substance By following such a beam path, a reflected beam reflected by the image forming substance detection sensor 22 and detected can be almost ignored. However, as shown in FIG. 6, when the image forming material is on the intermediate transfer belt 31, a part of the detection beam emitted from the image forming material detection sensor 32 cannot be ignored. The light is irregularly reflected by the image forming substance 33, follows the beam path 34, and is reflected and detected by the image forming substance detection sensor 32. Based on the above principle, the position of the image forming substance on the intermediate transfer belt is specified.
[0010]
As an application example of such a principle, there is color shift correction in a tandem type color printer. The tandem type color printer has four image forming units each storing image forming substances including four different color materials of cyan toner, magenta toner, yellow toner, and black toner, and finally has a recording paper or OHP recording. A color image is formed by transferring each color toner to the medium, but the deviation of the formation position of each color toner at this time becomes a color deviation on the recording medium and is visually recognized by human eyes. To prevent this, the amount of color misregistration can be calculated and corrected by detecting the position of each color toner on the intermediate transfer belt using a reflection type infrared sensor as an image forming substance detection sensor.
[0011]
More specifically, as shown in FIG. 7, for example, image patterns for detecting the amount of color misregistration of each color toner, which are called registration correction patterns 4b and 4c, are formed on the intermediate transfer belt 4a. The registration sensors 4d and 4e are installed one by one on the left and right on the intermediate transfer belt 4a, and the movement of the intermediate transfer belt 4a detects the registration correction pattern 4b or 4c in the row. The resist correction patterns 4b and 4c have the same color pattern formed at positions symmetrical to each other with respect to the symmetry line 4f in the sub-scanning direction, and the shape itself is mirror-symmetrical with respect to the sub-scanning direction with respect to the symmetry line. It is formed as follows.
[0012]
As for the left and right registration correction patterns 4b and 4c, each color of the registration correction patterns passes through the registration sensor 4d or 4e as the intermediate transfer belt 4a moves. At this time, the moving speed of the intermediate transfer belt 4a must be kept as constant as possible. Each of the registration sensors 4d and 4e outputs a detection signal when a registration correction pattern of each color comes to a position immediately below the sensor.
[0013]
In this way, for example, by measuring the time when the detection signal is output for each color of the resist correction pattern, determining the time that is the center of the time, and comparing the center detection time for each color with each other (for example, black The deviation from the originally expected value of the image forming start time and position of the image forming unit of each color can be calculated by comparing with the reference). The color shift can be reduced by correcting various parameters related to each image formation based on the calculated shift amount.
[0014]
In order to manufacture a color image forming apparatus at a lower cost, a method is considered in which the intermediate transfer unit is abolished and an image is formed directly from the image forming unit on a recording medium. For example, FIG. 8 shows an example of the internal configuration of a color image forming apparatus without an intermediate transfer unit. In the case of this configuration example, the recording medium passes from the recording medium storage unit 55 between the photoconductor 52 and the transfer roller 57. Is discharged from the discharge unit 59 through the inside of the fixing unit 58. Therefore, for the purpose of, for example, color shift correction or image forming substance amount correction as described in the above “prior art”, the formation position of each image forming substance and the image forming substance density per unit area are used. When an attempt is made to detect an image forming parameter, an image formed on a recording medium is formed on each of the photoconductors 52 or on the rear side of the space between the photoconductor 52 and the transfer roller 57 (that is, on the discharge unit 59 side). There is no choice but to detect the substance directly.
[0015]
If detection is to be performed on each photoreceptor, for example, in a color image forming apparatus having the configuration shown in FIG. 8, four times as many image forming substance detection sensors as in the prior art are required, and the intermediate transfer unit is eliminated. Cost merit decreases. Therefore, the image forming substance detection sensor must be disposed on the rear side (that is, on the discharge unit 59 side) of between the photoconductor 52 and the transfer roller 57.
[0016]
When the recording medium is paper, since the paper itself is white and has irregularities on the surface, unlike the case of the intermediate transfer unit, visible light is used instead of infrared light, and as shown in FIG. In addition, the sensor unit must be formed so as to detect direct light instead of scattered light.
[0017]
Other image forming parameters to be corrected include the amount of the image forming substance in the image forming unit 11. The amount of the image forming substance is proportional to the amount of the image forming substance sent to the photoconductor 12. That is, when the amount of the image forming substance in the image forming unit 11 increases, the discharge pressure to the photoconductor 12 increases, so that the amount of the image forming substance sent to the photoconductor 12 increases. When the amount of the image forming substance sent to the photoreceptor 12 increases, the amount of the image forming substance adhering to the photoreceptor 12, and eventually the intermediate transfer belt and the recording medium increases. As the amount of adhesion increases, the density of the image forming substance per unit area on the intermediate transfer belt or the recording medium increases, the scattered light in FIG. 6 also increases, and as a result, the reflected light to the image forming substance detection sensor 32 also increases. . Therefore, the reflected light level at the image forming substance density per unit area on the intermediate transfer belt or the recording medium corresponding to the originally appropriate amount of the image forming substance in the image forming unit 11 is stored in advance, and the actual reflected light level is stored. By comparing the detected light level with the detected light level, it can be determined whether the amount of the image forming substance in the image forming unit 11 at that time is larger or smaller than the original substance amount. An action of replenishing the inside of the image forming unit can be taken.
[0018]
10 and 11 show an example of a density correction pattern for forming each color of toner as an image forming substance on a recording medium (recording paper) in a color image forming apparatus having a configuration without an intermediate transfer unit. FIG. 5 is an enlarged view of a density correction pattern 7b.
[0019]
[Problems to be solved by the invention]
However, the above conventional technique has the following problems.
[0020]
When an image forming substance pattern detection system of a color image forming apparatus having no intermediate transfer member is to be manufactured at a lower cost, a sensor for detecting a resist correction pattern and a sensor for detecting the amount of an image forming substance are commonly used. It is desirable. However, when detecting the resist correction pattern described in the above-mentioned `` prior art '', it is only necessary to be able to detect whether or not the image forming substance is present, but if it is intended to detect a density change of the image forming substance, Also, a sensor for detecting the same requires a certain dynamic range.
[0021]
In order to secure a dynamic range, the amount of light on the light emitting side of the sensor must be increased, or the sensitivity on the light receiving side must be increased. However, if the light amount on the light emitting side is increased, the power consumption increases, and if the sensitivity on the light receiving side is excessively increased, it becomes weak to noise and the responsiveness decreases. On the other hand, when the response is lowered, there is a risk that the resist correction pattern cannot be detected because the pattern width is narrow. If the sensitivity on the light receiving side is too high, the sensitivity of the sensor is saturated before reaching the density range of the image forming substance to be detected, and a change in density may not be detected. As described above, the sharing of the sensor has the above-described problem.
[0022]
SUMMARY OF THE INVENTION An object of the present invention is to provide a color image forming apparatus capable of inexpensively and accurately detecting a plurality of image forming parameters in an image forming substance.
[0023]
[Means for Solving the Problems]
In order to solve the above-described problems, the color image forming apparatus of the present invention includes an electromagnetic wave output member having a specific output wavelength or an output wavelength band, and a reflected wave in which the electromagnetic wave from the electromagnetic wave output member is reflected on a recording medium. An electromagnetic wave detector for detecting, and an electromagnetic wave output unit output control means for controlling the output of the electromagnetic wave output unit, and detecting one or more detection patterns formed on a recording medium using an image forming substance. Thus, in a color image forming apparatus that detects a specific forming parameter of the image forming substance formed on a recording medium and corrects a forming condition of the image forming substance, the electromagnetic wave output member output control unit includes: A different output control of a pattern formed on a recording medium is performed by using a forming material.
[0024]
Further, the color image forming apparatus of the present invention is characterized in that the electromagnetic wave output body output control means controls the magnitude or output time of the output of the electromagnetic wave output body.
[0025]
Further, in the color image forming apparatus of the present invention, the electromagnetic wave output member output control means performs continuous output when detecting a resist pattern and performs intermittent output when detecting a density pattern, so that different patterns are output. Output control is performed.
[0026]
With this configuration, it is possible to provide a color image forming apparatus that can detect a plurality of image forming parameters in an image forming substance at low cost and with high accuracy.
[0027]
By the way, the “recording medium” and “image forming substance” of the present invention generally use “recording paper” and “toner”, respectively, but are not particularly limited thereto. Further, the “intermittent output” of the present invention generally indicates pulse driving. That is, it is assumed that output and non-output are repeated at a certain ON / OFF frequency and a pulse duty ratio. The “electromagnetic wave” of the present invention is, for example, visible light, but is not limited thereto.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0029]
(Embodiment 1)
FIG. 2 is a configuration example of a color image forming apparatus control circuit for realizing the present invention. In this configuration example, the CPU 913 in the ECU (engine control unit) 901 in the main device has a role of executing software programmed in the program ROM 912. Within the scope of the present embodiment, at least a predetermined image is stored in the program ROM 912 under predetermined conditions, for example, when the power is turned on or when a certain number of continuous prints is reached during continuous printing. A pattern is formed (this part is omitted in FIG. 2), and at the same time, the electromagnetic wave output member 921 (in the case of this embodiment, LED) is controlled by the electromagnetic wave output member output control means 911 in accordance with the image pattern. And via the parallel I / O 917 (via the signal lines 9a and 9c), and at the same time, the voltage level output from the electromagnetic wave detector 922 (in this embodiment, a phototransistor) Is detected from the signal line 9b via the A / D converter 914.
[0030]
If the formed image pattern is a pattern for density detection, the detected voltage level is allowed by comparing the detected voltage level with the table data stored in the voltage / density conversion table 915. It is determined whether or not the toner concentration in the developing device is within the range.
[0031]
If the formed image pattern is a resist correction pattern, for example, using the method described in the above-mentioned “prior art”, a position shift in image formation of each color is detected, and a latent image is formed on the photoconductor. By using a method such as adjusting the output timing of an LSU (laser scanning unit) for forming the image, the positional deviation of the image formation of each color is corrected (this part is also omitted in FIG. 2).
[0032]
In this configuration example, the electromagnetic wave output member output control means 911 is provided in the ECU 901, but it does not have to be particularly provided in the ECU 901, and may be provided in the image forming substance detection sensor 902. good. The present invention does not specify the location of the electromagnetic wave output member output control means.
[0033]
This configuration example is merely an example. For example, the voltage / concentration conversion table 915 may be in the program ROM 912, and the A / D converter 914 may be integrated with the CPU 913. The present invention does not particularly define a configuration example in the ECU 901.
[0034]
Further, the program ROM 912 stores a program for temporarily storing a plurality of voltage level data obtained from the electromagnetic wave detector 922 via the A / D converter 914 in the RAM 916 and performing processing such as averaging and peak value extraction. May be. The present invention does not particularly define a program stored in the program ROM 912.
[0035]
FIG. 3 is a circuit configuration example of the electromagnetic wave output member output control means 911 and the image forming substance detection sensor 902 in FIG. In FIG. 3, an electromagnetic wave output body output control means 911, an electromagnetic wave output body (LED) 921, an electromagnetic wave detection body (phototransistor) 922, and signal lines 9a and 9b correspond to those in FIG.
[0036]
In FIG. 3, when a high signal is applied to the signal line 9a, the transistor 10a in the electromagnetic wave output device output control means 911 is turned on, and a current flows from the collector C to the emitter E. Output an electromagnetic wave, that is, in the case of the present embodiment, visible light having a certain output wavelength or output wavelength band.
[0037]
Part of the electromagnetic wave (visible light) output from the electromagnetic wave output body (LED) 921 is reflected on the recording medium (recording paper) 10b, and is input to the electromagnetic wave detector (phototransistor) 922. The ratio of the reflected electromagnetic wave (visible light) is different between a portion where the image forming substance (toner) 10c is formed on the recording medium (recording paper) 10b and a portion where the image forming substance (toner) 10c is not formed. Since this also depends on the density at which 10c is formed, it causes a difference in voltage level in the output voltage (signal line 9b) from the electromagnetic wave detector (phototransistor) 922. Therefore, the relationship between the output voltage (signal line 9b) from the electromagnetic wave detector (phototransistor) 922 and the density of the image forming substance (toner) 10c formed on the recording medium (recording paper) 10b is investigated in advance. If the data is stored in the voltage / density conversion table 915 in FIG. 2, it can be determined whether or not the detected voltage level is an allowable toner density in the developing device.
[0038]
FIG. 1 shows an example of the drive signal line 9a of the electromagnetic wave output member output control means 911 in FIG. That is, the intermittent drive (FIG. 3) is continuously turned on when the registration correction pattern is detected, and the ON time 11c and the OFF time 11d are alternately repeated at a certain frequency when the toner density detection pattern is detected. Pulse drive). At the same time, by increasing the driving power supply V1 of the electromagnetic wave output unit (LED) 921 to a high voltage or by using an electromagnetic wave output unit operating current switching means such as switching the resistance value of the resistor R-LED to a small value, the electromagnetic wave output unit The output of the electromagnetic wave (visible light) from the (LED) 921 is instantaneously increased. Accordingly, the number of electromagnetic waves (visible light) input to the electromagnetic wave detector (phototransistor) 922 increases, so that the variable range of the output voltage (signal line 9b) from the electromagnetic wave detector (phototransistor) 922 increases. That is, the dynamic range is expanded. Simply increasing the operating current of the electromagnetic wave output body with continuous output increases power consumption, and there is a limit to the operating current rating, which limits the expansion of the dynamic range. ), Even if the operating current of the electromagnetic wave output body is instantaneously exceeded, the average value is kept within the rating, thereby achieving both expansion of the dynamic range, suppression of increase in power consumption, and compliance with the rating. You can do it.
[0039]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a color image forming apparatus capable of inexpensively and accurately detecting a plurality of image forming parameters in an image forming substance.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a drive signal line 9a of an electromagnetic wave output member output control means 911 in FIG. 3; FIG. 2 is a diagram showing a configuration example of a color image forming apparatus control circuit for realizing the present invention; FIG. 4 is a diagram showing a circuit of an electromagnetic wave output member output control means and an image forming substance detection sensor unit in FIG. 2; FIG. 4 is a diagram showing an internal configuration example of a conventional tandem type color image forming apparatus; FIG. 6 is a view showing a configuration example of a detection system for detecting an image forming substance (when the image forming substance is not placed on the intermediate transfer belt). FIG. 6 is a detection system for detecting the image forming substance on the intermediate transfer belt. FIG. 7 is a diagram showing a configuration example (in the case where an image forming substance is placed on an intermediate transfer belt) of a conventional tandem-type color image forming apparatus. FIG. 8 is a diagram showing an example of the internal configuration of a color image forming apparatus without an intermediate transfer unit. FIG. 9 is a configuration example of a detection system for detecting an image forming substance on a recording medium (recording paper) (image forming substance). FIG. 10 is a diagram illustrating a case where a color image forming apparatus having no intermediate transfer unit is used to form toner colors as image forming substances on a recording medium (recording paper). FIG. 11 shows an example of a density correction pattern to be changed. FIG. 11 is an enlarged view of a density correction pattern 7b in FIG.
11 Image forming unit 12 Photoconductor 13 LSU
14 Intermediate Transfer Unit 15 Recording Medium Storage 16 Recording Medium Transport Path 17 Transfer Roller 18 Fixing Unit 19 Ejector 21 Intermediate Transfer Belt 22 Image Forming Material Detection Sensor 24 Beam Path 25 Intermediate Transfer Belt Transport Direction 31 Intermediate Transfer Belt 32 Image Formation Material detection sensor 33 Image forming material 34 Beam path 35 Intermediate transfer belt transport direction 4a Intermediate transfer belt 4b, 4c Registration correction patterns 4d, 4e Registration sensor 4f Symmetry line 51 in sub-scanning direction on intermediate transfer belt 51 Image forming unit 52 Photoconductor 53 LSU
55 recording medium storage section 57 transfer roller 58 fixing section 59 discharge section 61 recording medium (recording paper)
62 Image forming substance detection sensor (light emitting side)
63 Image forming substance 64 Image forming substance detection sensor (light receiving side)
65 Intermediate transfer belt transport direction 7a Recording medium (recording paper)
7b, 7c Density correction patterns 7d, 7e Density sensor 7f Symmetry line 8y in sub-scanning direction on recording medium (recording paper) Yellow density detection patch 8m Magenta density detection patch 8c Cyan density detection patch 8k Black density detection patches 9a, 9b , 9c Signal line 901 ECU in main unit
902 Image forming substance detection sensor 911 Electromagnetic wave output body output control means 912 Program ROM
913 CPU
914 A / D converter 915 Voltage / concentration conversion table 916 RAM
917 Parallel I / O
921 Electromagnetic wave output body (LED)
922 Electromagnetic wave detector (phototransistor)
10a Transistor 10b for turning on / off electromagnetic wave output member 921 Recording medium (recording paper)
10c Image forming substance (toner)
B: Base of the transistor 10a for turning on / off the electromagnetic wave output member 921 C Collector of the transistor 10a for turning on / off the electromagnetic wave output member 921 Emitter V1 of the transistor 10a for turning on / off the electromagnetic wave output member 921 Electromagnetic wave output member 921 and electromagnetic wave output Driving power supply V2 of body control means 911 Driving power supply 11a of electromagnetic wave detector 922 Continuous output command section 11b of electromagnetic wave output body (LED) 921 when resist correction pattern is detected Electromagnetic wave output body (LED) when toner density detection pattern is detected One cycle section 11c of the intermittent output command 921 The ON time 11d of the electromagnetic wave output body (LED) 921 in one cycle section 11b of the intermittent output command of the electromagnetic wave output body (LED) 921 In one cycle section 11b Electromagnetic wave output member (LED) 921 OFF time

Claims (4)

An electromagnetic wave output body having a specific output wavelength or an output wavelength band, and an electromagnetic wave detector that detects a reflected wave of the electromagnetic wave from the electromagnetic wave output body reflected on a recording medium,
Electromagnetic wave output body output control means for controlling the output of the electromagnetic wave output body,
Has,
By detecting one or more detection patterns formed on a recording medium using an image forming substance, a specific forming parameter of the image forming substance formed on the recording medium is detected, and the image formation is performed. In a color image forming apparatus that corrects a formation condition of a substance,
The color image forming apparatus according to claim 1, wherein the output control means controls the output of a pattern formed on a recording medium using an image forming substance. 2. The color image forming apparatus according to claim 1, wherein the output control means controls the magnitude of the output of the electromagnetic wave output body or the output time. The electromagnetic wave output member output control means performs continuous output when detecting a resist pattern, and performs intermittent output when detecting a density pattern, thereby performing output control of different patterns. 3. The color image forming apparatus according to 1 or 2. The color image forming apparatus according to claim 1, wherein the electromagnetic wave is light having an output wavelength or an output wavelength band in a visible light region.

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