JP2003072984A - Paper remaining amount detecting device and image forming device - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a sheet remaining amount detecting device for accurately detecting the sheet remaining amount in a sheet tray and an image forming apparatus provided with the sheet remaining amount detecting device. A color image forming apparatus includes a paper sensor.
The paper cassette 1 detected by the paper remaining amount sensor 18 based on the light amount detection results with and without the paper 11 detected by the
2 accurately detects the remaining amount of the sheet 11. Then, the color image forming apparatus 1 conveys the paper 11 in accordance with the formation of the toner image in the image forming units 30Y to 30K.
The image forming speed can be increased, the remaining amount of paper in the paper cassette 12 is accurately determined, and the formation of toner images in the image forming units 30Y to 30K is controlled according to the remaining amount of paper 11. The paper 11 is gone, and the image forming units 30Y to 30Y-3
It is possible to prevent wasteful toner images formed on the 0K photoconductor drums 31Y to 31K.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a remaining paper amount detecting device and an image forming apparatus, and more particularly, to a remaining paper amount detecting device for accurately detecting the remaining amount of paper in a paper tray and the remaining paper amount detecting device. The present invention relates to an image forming apparatus including.

[0002]

2. Description of the Related Art Generally, in an electrophotographic image forming apparatus, a light latent image on a photoconductor is waited until a sheet reaches a registration sensor position immediately before a transfer position from a paper feed tray and the registration sensor is turned on. Writing has started.

Recently, however, there is an increasing demand for full-color image formation, and at the same time, there is a strong demand for higher speed. As a color image forming apparatus that meets such a demand, a so-called tandem type color image forming apparatus that forms a color image by juxtaposing a plurality of electrophotographic writing units and image forming cartridges and superposing the images The device is used.

The tandem type color image forming apparatus has a higher productivity as compared with a color image forming apparatus in which each color image is sequentially formed and transferred by a single photoconductor, because each color forms an image independently. It is characterized by high price.

In an image forming apparatus such as a color printer or a color copying machine which uses the tandem system and employs an intermediate transfer belt, an optical latent image on a photoconductor is used in order to increase the printing speed. The control of the writing start timing of the image forming apparatus other than the tandem type
It uses different methods.

That is, a color image forming apparatus such as a color printer or a color copying machine which uses a tandem system and employs an intermediate transfer belt generally forms a plurality of images of four colors of yellow, magenta, cyan and black. Image forming units are independently arranged along the conveyance direction of the intermediate transfer belt, and the toner images of the respective colors formed on the photosensitive drums of the respective image forming units are transferred from the paper feeding unit to the transfer position adjacent to the registration roller. Transfer to the conveyed paper. In this case, the color image forming apparatus is
Optical latent image writing is started from the photosensitive drum of the image forming portion of the color farthest from the transfer position, and this electrostatic latent image is developed with the toner of the color in the image forming portion to form the toner image of the color. Transfer to the intermediate transfer belt. For the other three colors, the color image forming apparatus sequentially writes the optical latent images on the photoconductor drums of the image forming portions of the colors far from the transfer position, and accurately prints the toner images of the respective colors on the intermediate transfer belt. It is synchronized and transferred so that it overlaps with. Then, the color image forming apparatus transfers the color toner image formed by superimposing the four colors onto the sheet at the transfer position adjacent to the registration roller.

In the conventional color image forming apparatus, the series of image forming operations is started after the registration sensor is turned on. In this case, the image formation farthest from the transfer position after the registration sensor is turned on is performed. The paper stands by until the writing of the optical latent image on the photoconductor drum of a part is started and the color toner image formed on the intermediate transfer belt reaches the transfer position on the paper.

The printing operation in this case is: registration sensor ON → image formation start → transfer of image to paper → registration sensor ON → next image formation start ...

[0009]

However, in the image forming apparatus using such a conventional tandem system and employing the intermediate transfer belt, the registration sensor is turned on, the image formation is started, and the image is transferred onto the sheet. → The registration sensor is turned on → The next image formation starts ... The printing operation is performed, so the time from the issuance of the print instruction until the printed paper is ejected becomes longer, and continuous printing is performed. In this case, the distance between the images becomes large and the printing speed is greatly reduced. In addition,
In the system which does not use the intermediate transfer belt, since the writing of the optical latent image is started from the photosensitive drum of the image forming portion at a position close to the registration sensor, the above-mentioned problem does not occur.

Therefore, in order to deal with the above problem in an image forming apparatus using a tandem system and employing an intermediate transfer belt, the image forming operation is not synchronized with the sheet but the sheet is synchronized with the image forming operation. I will let you.
That is, the image forming operation is started regardless of whether the registration sensor is turned on, and the sheet supply timing is adjusted by the registration rollers according to the toner image formed on the intermediate transfer belt. Then, at the time of continuous printing, it is possible to deal with the problem by forming a toner image on the intermediate transfer belt by shortening the interval between the images.

However, if the image forming operation is preceded,
Problems occur with paper presence detection. That is, when the image forming operation is started when the registration sensor is turned on, it is certain that there is a sheet on which the toner image is transferred, but when the image forming operation is preceded, the image corresponding to the formed image is dealt with. There is no guarantee that there will be paper to do. If the paper presence / absence sensor indicates that there is no paper at the start of image formation, image formation is not performed, but when there is only one sheet remaining and two or more sheets are output, the first image formation is performed. If you run out of paper after performing
The toner image of the first sheet is discarded without being transferred to the sheet. When the paper transport path from the paper tray to the registration roller position is long and there are two or more sheets in the transport path, the toner image to be discarded may be the third one instead of the second one. . Further, when a plurality of images are placed between the primary transfer position and the secondary transfer position of the image forming portion farthest from the two-character transfer position on the intermediate transfer belt, a plurality of toner images are discarded, There is a problem that resources are wasted and the usability of the image forming apparatus is poor.

Therefore, according to the first aspect of the present invention, the light is emitted from the light emitting element of the remaining paper amount detection sensor having the light emitting element and the light receiving element which are disposed with the paper placed in the paper tray interposed therebetween, and the paper is transmitted. When the remaining amount of paper in the paper tray is detected based on the amount of light received by the light receiving element, the paper having the light emitting element and the light receiving element on the paper conveyance path of the paper conveyed from the paper tray to the image forming position. The sensor is arranged with the light emitting element and the light receiving element sandwiching the conveyed sheet, and the amount of light received by the light receiving element through the sheet emitted from the light emitting element of the sheet sensor and the sheet and the sheet. In the absence of light, the light transmittance of each sheet is calculated from the amount of light received from the light emitting element and received by the light receiving element, and based on the light transmittance of the sheet, the light received by the remaining sheet amount detection sensor is detected. element By detecting the remaining amount of paper in the paper tray from the amount of received light, the transmissivity of each type of conveyed paper is detected for various types of paper, and the remaining amount of paper in the paper tray is calculated from the transmissivity. It is an object of the present invention to provide a remaining paper amount detection device capable of detecting the remaining amount of paper and accurately detecting the remaining amount of paper regardless of the type of paper.

According to the second aspect of the present invention, the amount of light emitted from the light emitting elements of the remaining paper amount detection sensor and the paper sensor is adjusted based on the light transmittance per sheet detected by the paper sensor, and To provide a sheet remaining amount detecting device capable of preventing the amount of light received by a light receiving element from becoming insufficient depending on the type and always performing a detection process with a sufficient amount of light to detect the remaining amount of paper more accurately. It is an object.

According to a third aspect of the present invention, in the developing unit, a toner image is formed by forming an electrostatic latent image on a photosensitive member which is rotationally driven, and then toner is attached to the photosensitive member, and the toner image of the photosensitive member is intermediately transferred. The toner image transferred to the intermediate transfer belt is transferred to the belt at the primary transfer position, conveyed from the paper tray, detected by the registration sensor, adjusted in timing by the registration roller, and conveyed to the secondary transfer position. Based on the amount of light received by the light receiving element that is emitted from the light emitting element of the remaining paper amount detection sensor that has the light emitting element and the light receiving element that are transferred and that sandwich the paper in the paper tray. When detecting the remaining amount of paper in the paper tray, the image is formed in the developing section regardless of whether the registration sensor detects the paper A paper sensor having a light emitting element and a light receiving element is arranged on the paper transporting path of the paper to be carried in such a state that the light emitting element and the light receiving element sandwich the transported paper, and the light is emitted from the light emitting element of the paper sensor. The light transmittance per sheet is calculated from the amount of light received by the light receiving element after passing through the conveyed and conveyed paper and the amount of light received by the light receiving element emitted from the light emitting element in the absence of the paper. Based on the light transmittance of one sheet of paper, the remaining amount of paper in the paper tray is detected from the amount of light received by the light receiving element of the remaining paper amount detection sensor, and image formation in the developing unit is performed based on the detected remaining amount of paper. By accurately controlling the remaining amount of paper, the image formation in the developing unit is controlled by the remaining amount of the paper, and the image is formed in the state where the paper is not conveyed in the conveyance path and toner is wasted. To prevent Together eliminate unnecessary, and its object is to provide an excellent image forming apparatus availability.

According to a fourth aspect of the present invention, the amount of light emitted from the light emitting elements of the remaining paper amount detection sensor and the paper sensor is adjusted based on the light transmittance per sheet detected by the paper sensor, thereby Depending on the type, the received light amount of the light receiving element is prevented from becoming insufficient, and the detection process is always performed with a sufficient light amount to detect the remaining amount of paper more accurately, and more appropriately waste resources. An object of the present invention is to provide an image forming apparatus with good usability.

[0016]

According to another aspect of the present invention, there is provided an image forming apparatus including a paper remaining amount detecting sensor having a light emitting element and a light receiving element, which are arranged with a paper placed in a paper tray sandwiched therebetween. A remaining paper amount detecting device for detecting the remaining amount of the paper in the paper tray based on the amount of light received by the light receiving element that is emitted from the light emitting element of the remaining paper amount detecting sensor, passes through the paper, and is received. A paper sensor having a light emitting element and a light receiving element is provided on a paper transporting path of the paper transported from the paper tray to an image forming position, with the light emitting element and the light receiving element sandwiching the transported paper. The amount of light received by the light receiving element, which is emitted from the light emitting element of the sheet sensor, passes through the conveyed sheet, and is received by the light receiving element, and is emitted from the light emitting element without the sheet and is received by the light receiving element. The light transmittance per sheet is calculated from the light amount, and based on the light transmittance per sheet, the amount of light received by the light receiving element of the paper remaining amount detection sensor is used to determine the remaining amount of paper in the paper tray. By detecting the amount,
It has achieved the above objectives.

According to the above construction, the light-receiving element which is emitted from the light-emitting element of the remaining paper amount detection sensor having the light-emitting element and the light-receiving element, which are arranged with the sheet placed in the paper tray interposed therebetween, passes through the sheet and is received. When detecting the remaining amount of paper in the paper tray based on the amount of light received by the paper tray, a paper sensor having a light emitting element and a light receiving element is provided on the paper transport path of the paper transported from the paper tray to the image forming position. The light emitting element and the light receiving element are arranged so as to sandwich the conveyed paper, and the amount of light received by the light receiving element through the paper emitted from the light emitting element of the paper sensor and received by the light receiving element and the state without the paper. The light transmittance per sheet is calculated from the amount of light received from the light emitting element and received by the light receiving element, and based on the light transmittance per sheet, the amount of light received by the light receiving element of the remaining paper amount detection sensor. From Since the remaining amount of paper in the paper tray is detected, it is possible to detect the transmissivity of each conveyed sheet for various types of paper and detect the remaining amount of paper in the paper tray from the transmissivity. Therefore, the remaining amount of paper can be accurately detected regardless of the type of paper.

In this case, for example, as described in claim 2, the sheet remaining amount detecting device is configured so that the sheet remaining amount detecting sensor and the sheet remaining amount detecting sensor are based on the light transmittance per sheet detected by the sheet sensor. The amount of light emitted from the light emitting element of the paper sensor may be adjusted.

According to the above construction, the light emission amount of the light emitting elements of the remaining paper amount detecting sensor and the paper sensor is adjusted based on the light transmittance per sheet detected by the paper sensor, so that the light receiving amount depends on the kind of the paper. It is possible to prevent the amount of light received by the element from becoming insufficient, and it is possible to detect the remaining amount of paper more accurately by always performing detection processing with a sufficient amount of light.

According to the image forming apparatus of the present invention, a developing unit forms an electrostatic latent image on a photosensitive member that is rotationally driven and then attaches toner to form a toner image. The image is transferred to the intermediate transfer belt at the primary transfer position, transferred from the paper tray, detected by the registration sensor, adjusted in timing by the registration roller, and transferred to the intermediate transfer belt on the sheet conveyed to the secondary transfer position. The light receiving element which is transferred from the light emitting element of the remaining paper amount detection sensor having a light emitting element and a light receiving element which sandwich the paper in the paper tray and which transmits the transferred toner image and transmits the paper. In an image forming apparatus that detects the remaining amount of the paper in the paper tray based on the amount of received light of the paper, regardless of whether the registration sensor detects the paper, Performs image formation at the image portion,
A paper sensor having a light emitting element and a light receiving element is arranged on the paper transporting path of the paper transported from the paper tray to the registration roller in a state where the light emitting element and the light receiving element sandwich the transported paper. The amount of light received from the light emitting element of the paper sensor and transmitted through the conveyed paper to be received by the light receiving element and the amount of light received from the light emitting element without the paper and received by the light receiving element The light transmittance for each sheet is calculated, and the remaining amount of paper in the paper tray is detected from the amount of light received by the light receiving element of the remaining paper amount detection sensor based on the light transmittance for each sheet. Then, the above object is achieved by controlling the image formation in the developing section based on the detected remaining amount of paper.

According to the above construction, after the electrostatic latent image is formed on the photosensitive member which is rotationally driven in the developing unit, toner is attached to form a toner image, and the toner image of the photosensitive member is transferred onto the intermediate transfer belt. The toner image transferred to the intermediate transfer belt is transferred to the sheet which is transferred at the primary transfer position, is conveyed from the inside of the paper tray, is detected by the registration sensor, is adjusted in timing by the registration roller and is conveyed to the secondary transfer position. At the same time, the paper tray is based on the amount of light received by the light receiving element that is emitted from the light emitting element of the remaining paper amount detection sensor that has a light emitting element and a light receiving element that are arranged with the paper in the paper tray. When detecting the remaining amount of paper inside, the image is formed in the developing section regardless of whether the registration sensor detects the paper and the paper is transferred from the paper tray to the registration roller. The feed is being paper transport path of the sheet, the sheet sensor having a light emitting element and a light receiving element, distribution and set in a state of sandwiching the paper in which the light-emitting element and the light receiving element is the transport,
Light per sheet based on the amount of light received by the light receiving element that is transmitted from the light emitting element of the sheet sensor and transmitted through the conveyed sheet and the amount of light received by the light receiving element that is emitted from the light emitting element without the sheet. Calculate the transmittance and calculate the paper 1
Based on the light transmittance per sheet, the remaining amount of paper in the paper tray is detected from the amount of light received by the light receiving element of the remaining paper amount detection sensor, and image formation in the developing unit is controlled based on the detected remaining amount of paper. Therefore, the remaining amount of paper is accurately detected, and the image formation in the developing unit is controlled by the remaining amount of the paper, so that the image is formed in the state where the paper is not conveyed in the conveyance path and the toner is wastefully consumed. Can be prevented, waste of resources can be saved, and usability can be improved.

In this case, for example, as described in claim 4, the image forming apparatus uses the sheet remaining amount detecting sensor and the sheet based on the light transmittance per sheet detected by the sheet sensor. The amount of light emitted from the light emitting element of the sensor may be adjusted.

According to the above configuration, the light emission amount of the light emitting elements of the remaining paper amount detection sensor and the paper sensor is adjusted based on the light transmittance per sheet detected by the paper sensor, so that the light receiving amount depends on the kind of the paper. It is possible to prevent the amount of light received by the element from becoming insufficient, always perform detection processing with a sufficient amount of light, more accurately detect the remaining amount of paper, and more appropriately waste resources. As well as
The usability can be further improved.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and therefore have various technically preferable limitations. However, the scope of the present invention refers to the present invention particularly in the following description. Unless otherwise stated, the present invention is not limited to these embodiments.

1 to 3 are views showing a first embodiment of a remaining paper amount detecting apparatus and an image forming apparatus of the present invention.
FIG. 1 is a schematic configuration diagram of a color image forming apparatus 1 to which a first embodiment of a sheet remaining amount detecting apparatus and an image forming apparatus of the present invention is applied, and FIG. 2 is a control of the color image forming apparatus 1 of FIG. It is a block block diagram of a system.

In FIG. 1, the color image forming apparatus 1 is
The paper feed unit 10, the transfer belt mechanism unit 20, and the image forming units 30Y of the respective colors of yellow (Y), magenta (M), cyan (C), and black (K), which are arranged along the transfer belt mechanism unit 20, 30M, 30C, 30K and secondary transfer section 40
In addition to these, although not shown, a fixing unit, a motor, and a drive mechanism unit that transmits a drive source to each unit driven by the motor are provided.

The paper feed unit (paper tray) 10 has a paper feed cassette 12 into which a plurality of papers 11 as transfer materials are loaded, a pickup roller 13 for feeding out the papers 11 in the paper feed cassette 12 one by one, and a pickup roller 13. Of a plurality of pairs of conveying rollers 14 for conveying the sheet 11 sent by the above, the registration rollers 15, and the sheet 1 conveyed to the registration rollers 15.
A sheet sensor 16 including a light emitting element portion 16a and a light receiving element portion 16b that detect 1 and a registration sensor 17 that is disposed in front of the registration roller 15 and detects that the sheet 11 has been conveyed to the position of the registration roller 15 are provided. In addition to the above, a paper remaining amount sensor (paper remaining amount detection sensor) 18 that detects the remaining amount of the paper 11 (paper remaining amount) in the paper feed cassette 12 is provided.

The paper feed unit 10 feeds the paper 11 in the paper feed cassette 12 one by one by a pickup roller 13, and conveys the fed paper 11 to a registration roller 15 by a plurality of conveyance rollers 14. This registration roller 15
The sheet sensor 16 detects the sheet 11 being conveyed to the sheet, and the registration sensor 17 detects that the sheet 11 has been conveyed to the registration roller 15.

The registration roller 15 is provided with a paper feed clutch and the like, adjusts the timing of the paper 11 sent from the paper feed cassette 12, and sends the paper 11 to the transfer belt mechanism 20 at a predetermined timing.

The paper remaining amount sensor 18 is used for the paper feed cassette 12.
The light-emitting element unit 1 while sandwiching the paper 11 set in the
8a and a light receiving element portion 18b are provided, and the light emitted from the light emitting element portion 18a toward the light receiving element portion 18b and transmitted through the paper 11 is received by the light receiving element portion 18b, and the light receiving element portion 18b receives the light. A paper remaining amount signal corresponding to the light amount is output to the sensor signal processing circuit 59 shown in FIG.

The transfer belt mechanism section 20 comprises an intermediate transfer belt 21, a plurality of conveying rollers 22 to 24, and the like.
The intermediate transfer belt 21 includes the transport rollers 22 to 2
It has been stretched to 4. The transfer belt mechanism unit 20 rotates at least one of the transport rollers 22 to 24 by a drive mechanism such as a motor (not shown) to rotate the intermediate transfer belt 21 clockwise in FIG. 2 at a position facing the transport roller 24 with the belt 21 in between.
The next transfer unit 40 is arranged.

The transfer belt mechanism 20 includes a conveying roller 22.
1 to 24, the intermediate transfer belt 21 is sequentially conveyed in the clockwise direction in FIG. 1 to the image forming units 30Y, 30M, 30C, and 30K of the respective colors, and the image forming units 30Y, 30M, 30C, and 30K of the respective colors,
A yellow toner image, a magenta toner image, a cyan toner image, and a black toner image are sequentially transferred onto the intermediate transfer belt 21.

Image forming units 30Y, 30M, 30C and 3 for each color
0K indicates charging portions 32Y to 32K and print heads 33Y to 33 around the photosensitive drums 31Y to 31K, respectively.
K, developing units 34Y to 34K, transfer units 35Y to 35K, cleaning units 36Y to 36K, and the like are provided.

The photosensitive drums 31Y to 31K are rotationally driven counterclockwise in FIG. 1 by a driving mechanism (not shown), and the charging units 32Y to 32K uniformly charge the photosensitive drums 31Y to 31K. The print heads 33Y to 33K are, for example,
LE with many LED elements arranged in an array in the main scanning direction
The D head is used, the writing light modulated by the image data is applied to the photoconductor drums 31Y to 31K to form an electrostatic latent image on the photoconductor drums 31Y to 31K.
4Y to 34K are photosensitive drums 3 on which an electrostatic latent image is formed.
Toners of respective colors of yellow (Y), magenta (M), cyan (C) and black (K) are adhered to 1Y to 31K to form toner images of respective colors.

The transfer portions 35Y to 35K are arranged with the position facing the photosensitive drums 31Y to 31K with the intermediate transfer belt 21 interposed therebetween as a primary transfer position, and apply a transfer potential to the intermediate transfer belt 21. , Photosensitive drums 31Y-3
Yellow (Y), magenta (M), cyan (C), and black (K) toner images on 1K are sequentially transferred to the intermediate transfer belt 21.

At this time, the color image forming apparatus 1 performs timing so that the toner images formed on the photoconductor drums 31Y to 31K are accurately overlapped on the intermediate transfer belt 21 at the transfer portions 35Y to 35K. Control and transfer.

The cleaning sections 36Y to 36K are equipped with, for example, blades and the like, and the photosensitive drum 3 on which transfer has been completed.
The transfer residual toner remaining on 1Y to 31K is cleaned. Further, the cleaning units 36Y to 36K include a charge removing unit (not shown), and the charge removing light is radiated to the photoconductor drums 31Y to 31K to remove the charge from the photoconductor drums 31Y to 31K.
Is neutralized and averaged to the reference potential.

In the color image forming apparatus 1, as described above, the toners of yellow (Y), magenta (M), cyan (C) and black (K) are superposed and transferred to form a color toner image. Formed intermediate transfer belt 2
1 is conveyed between the conveying roller 24 and the secondary transfer portion 40, and the color toner image on the intermediate transfer belt 21 is conveyed between the conveying roller 24 and the secondary transfer portion 40 by the secondary transfer portion 40. Paper 1 sent out from the registration roller 15
Transfer to 1.

The color image forming apparatus 1 conveys the paper 11 on which the transfer has been completed to a fixing unit (not shown), and heats and pressurizes the fixing unit (not shown) to form a color toner image on the paper 11.
The sheet is fixed at 1, and is ejected onto a sheet ejection tray by a sheet ejection roller (not shown).

The color image forming apparatus 1 has a control system configured as shown in FIG. 2, and has a CPU (Centra).
l Processing Unit) 50, ROM (Read Only Memor)
y) 51, RAM (Random Access Memory) 52, head drive units 53a to 53d, motor / actuator drive unit 54, high-voltage power supply unit 55, various sensors 56, sensor signal processing units 57 to 59, and image processing device 60 In addition, the print heads 33Y to 33K and the paper sensor 1
6 and a sheet remaining amount sensor 18 and the like.

The ROM 51 stores various programs such as a basic program as the color image forming apparatus 1 and a sheet remaining amount detection processing program and an image formation timing control processing program, which will be described later, and various data necessary for executing these programs. The RAM 52 stores various data necessary for the operation of the color image forming apparatus 1.

The CPU 50 controls each part of the color image forming apparatus 1 based on the program in the ROM 51 while using the RAM 52 as a work memory to execute the basic processing as the color image forming apparatus 1 and to execute a sheet described later. The remaining amount detection process and the image formation timing control process are executed.

The image processing unit 60 analyzes print information transmitted from a host device such as a computer (not shown) and converts it into video data for each color, and the CPU 5
Transfer to 0. The CPU 50 uses the ROM 5 as described above.
The video data transferred from the image processing unit 60 is distributed to each head driving unit 53Y to 53K by operating in accordance with the program stored in No. 1.

The print heads 33Y to 33K are connected to head drive units 53Y to 53K, and the head drive units 53Y to 53K transfer the video data for each color to the print heads 33Y to 33K to print the print heads. 33Y-33
Writing to the photosensitive drums 31Y to 31K by K is performed. At this time, it is necessary to adjust the timing of transferring the video data of each color to the print head so that the image latent image formation start phase is appropriate, but a memory function for temporarily holding the video data of each color is required.

This memory function is implemented by the image processing unit 6
Since the image processing unit 60 is preferably provided in 0, in the present embodiment, the image processing unit 60 includes a memory for timing adjustment, and the transfer timing of each color video data transferred from the image processing unit 60 to the CPU 50. Adjust.

The writing of the latent image in the main scanning direction by the print heads 33Y to 33K needs to be started at a fixed timing in order to align the heads of the main scans.
When the LED heads are used as 3Y to 33K, it is necessary to drive the LED elements in the LED array at fixed timings in order to avoid concentration of power consumption in the print heads 33Y to 33K. The drive control operation of these print heads 33Y to 33K is performed by the head drive unit 15a.
~ 15d is doing.

The motor / actuator driving section 54 controls the driving of the transfer belt 21, the photoconductor drums 31Y to 31K and other elements (not shown) for driving the motors and clutches.

The high-voltage power supply unit 55 includes charging units 32Y to 32Y.
A high-voltage power source necessary for the K, the developing units 34Y to 33K, the transfer units 35Y to 35K, the cleaning units 36Y to 36K, and other components (not shown) is appropriately supplied according to a command from the CPU 50.

Paper sensor 16 and paper remaining amount sensor 18
Will be described later in detail, the sensor signal processing circuit 5 generates an analog detection signal according to the amount of light passing through the paper 11.
8 and 59, and the sensor signal processing circuit 58 and the sensor signal processing circuit 59 A / D-convert the analog detection signal and output it to the CPU 50.

The various sensors 56 are other kinds of sensors necessary for constructing the electrophotographic color image forming apparatus 1, and detect various operations necessary for the operation of the color image forming apparatus 1 to perform analog operation. The detection signal is output to the sensor signal processing circuit 57.

The sensor signal processing circuit 57 includes various sensors 5.
The analog detection signal input from 6 is A / D converted and output to the CPU 50.

Paper sensor 16 and paper remaining amount sensor 18
The light emitting element portions 16a and 18a and the light receiving element portions 16b and 18b have the same characteristics as shown in FIG. Paper sensor 16
The sheet remaining amount sensor 18 uses the light emitting diode D1 as a light emitting element and the photodiode D2 as a light receiving element. The light emitting element portions 16a and 18a are connected to the light emitting diode D1 to which the resistor R1 is connected. Power supply Vcc
Is being applied. In addition, the light receiving element portions 16b and 18b
The photodiode D2 is connected to the negative input terminal of the amplifier AMP, and the comparison voltage Vref is input to the positive input terminal of the amplifier AMP. Amplifier AMP
A resistor R2 is connected between the output terminal and the negative input terminal of the resistor R3, and a resistor R3 connected in parallel with the resistor R2 and in series with the photodiode D2 is connected.

Between the light emitting diode D1 of the light emitting element portions 16a and 18a and the photodiode D2 of the light receiving element portions 16b and 18b, in the case of the paper sensor 16, 0 to 1 sheets of paper 11 are left. In the case of the sensor 18, 0 to
The maximum number of sheets of paper 11 set in the paper feed cassette 12 is interposed, and the light emitted from the light emitting diode D1 is attenuated according to the number of the sheets of paper 11 interposed therebetween and is incident on the photodiode D2. The photodiode D2 generates a photocurrent Ip according to the amount of received light, is current-voltage converted by the amplifier AMP, and is output to the sensor signal processing circuits 58 and 59 as an analog output S. In this case, the light emission distributions of the light emitting diode D1 and the photodiode D2 are matched with the spectral sensitivity.

The output voltage S of the amplifier AMP is S
= Vref−R2 × Ip, and the difference voltage between the comparison voltage Vref and the output voltage S becomes a value proportional to the amount of received light.
However, the comparison voltage Vref is a reference voltage for keeping the operating point of the output S within an appropriate range.

Since the timing of the paper 11 is adjusted by the registration roller 15 before being sent to the secondary transfer portion 40 which is the secondary transfer position, the paper sensor 16 should be arranged near the registration roller 15. Thus, the amount of transmitted light per sheet can be stably detected by the sheet sensor 16 while the sheet 11 is stationary.

When the registration sensor 17 is turned on, it can be determined that the paper 11 is at the position of the registration roller 15, and the detection operation of the paper sensor 16 can be started by this ON signal of the registration sensor 17. You can Further, the amount of light received by the receiving element portion 16b of the paper sensor 16 when there is no paper 11 can be detected between the papers of the paper 11. Therefore, the transmittance per sheet of paper 11 can be obtained by comparing the amount of received light with and without the paper 11.

In the case of the paper remaining amount sensor 18, the operation becomes effective when the remaining amount of paper is the last few sheets, and when the paper 11 is a commonly used plain paper,
For example, the amount of light when passing through the paper 11 from the light emitting diode D1 when passing through the overlap of six or more sheets of paper 11 is small, and the detection output of the photodiode D2 cannot be effectively used. For the purpose of the color image forming apparatus 1, it is sufficient if the last few sheets of paper 11 in the paper feed cassette 12 can be detected.

To detect the remaining amount of paper by the remaining paper amount sensor 18, the light transmittance of one sheet of paper in the paper sensor 16 and the amount of light received when the number of sheets of paper 11 is 0 are calculated, and these light transmissions are calculated. Utilizing the rate and the amount of received light. That is, the amount of light received when the number of sheets of paper 11 is 0 is sequentially multiplied by the transmittance per sheet of paper to estimate the amount of light received when there are multiple sheets of paper 11, and the estimated amount of light received for each number of sheets is estimated. And the actual amount of received light are compared, and the closest number is determined as the remaining amount of paper. The CPU 50 performs this determination process.

Therefore, the paper sensor 16 having the light emitting element portion 16a and the light receiving element 16b, and the light emitting element portion 18a.
Paper remaining amount sensor 18 and CP having light receiving element 18b
U50 functions as a sheet remaining amount detecting device as a whole.

When the sheet characteristics are obtained by the sheet sensor 16, it is possible to take the variation of the sheet 11 into consideration and obtain a plurality of pieces of data for statistical processing.

Next, the operation of this embodiment will be described. The color image forming apparatus 1 according to the present embodiment not only synchronizes the image forming operation with the sheet but also synchronizes the sheet with the image forming operation, thereby increasing the processing speed and
The presence or absence of paper is detected with high accuracy, and the image forming units 30Y to 30
It is characterized in that the formation of an unnecessary toner image on the photosensitive drums 31Y to 31K in K is prevented, and an appropriate image is formed.

That is, when the start of the printing operation is instructed, the color image forming apparatus 1 starts the image forming operation in the image forming units 30Y to 30K regardless of the ON operation of the registration sensor 17, and the intermediate transfer belt 21. The registration roller 15 adjusts the paper supply timing in accordance with the toner image formed above.

Therefore, when the start of the printing operation is instructed, the color image forming apparatus 1 causes the respective image forming units 30Y to 30K.
The photoconductor drums 31Y to 31K are rotationally driven, the photoconductor drums 31Y to 31K cleaned by the cleaning units 36Y to 36K are uniformly charged by the charging units 32Y to 32K, and the photoconductor drums 31Y are uniformly charged. ~ 31K
Then, the writing light modulated by the image data is irradiated by the print heads 33Y to 33K in synchronization with the writing timing in each of the image forming units 30Y to 30K to form an electrostatic latent image.

At this time, the color image forming apparatus 1 starts irradiation of writing light from the image forming unit 30Y farthest from the secondary transfer unit 40 to form a toner image on the photosensitive drum 31Y, and the intermediate image is formed. The photoconductor drum 31Y is attached to the transfer belt 21.
Transfer the above toner image. And then, secondly 2
The writing image is irradiated by the image forming unit 30M located far from the next transfer unit 40, and the toner image is similarly transferred to the intermediate transfer belt 21.
The image forming operation is sequentially performed from the image forming units 30Y to 30K located far from the secondary transfer unit 40, and the operation is transferred to the intermediate transfer belt 21. At this time, the color image forming apparatus 1 performs timing so that yellow (Y), magenta (M), cyan (C), and black (K) toners are accurately superimposed and transferred onto the intermediate transfer belt 21. adjust.

On the other hand, in the color image forming apparatus 1, the paper feeding unit 10 is in synchronization with the image formation by the writing units 13a to 13f.
Then, the paper 11 is conveyed. That is, the paper feed cassette 1
The paper 11 in 2 is sent out one by one by a pickup roller 13, and the sent paper 11 is conveyed to a registration roller 15 by a plurality of conveying rollers 14. The sheet sensor 16 detects the sheet 11 conveyed to the registration roller 15, and the registration sensor 17 detects that the sheet 11 is conveyed to the registration roller 15.

When the registration sensor 17 detects that the paper 11 is conveyed to the registration roller 15, the paper sensor 16 detects the paper 11, and the detection signal of the light receiving element portion 16b of the paper sensor 16 at this time is detected. The CPU 50 obtains the transmittance per sheet of the sheet 11 from the size (light receiving amount).

The color image forming apparatus 1 has a CPU
Numeral 50 indicates the remaining amount of the paper in the paper feed cassette 12 by using the light transmittance per sheet of the paper 11 by the paper sensor 16 and the light transmittance and the light reception amount from the light reception amount when the paper 11 is zero. To judge. That is, the CPU 50 sequentially multiplies the amount of light received when the number of sheets 11 is 0 by the transmittance per sheet to estimate the amount of light received when the number of sheets 11 overlap, and for each estimated number of sheets. The amount of received light is compared with the actual amount of received light, and the closest number is determined as the remaining amount of paper in the paper feed cassette 12.

Therefore, the color image forming apparatus 1 does not form the toner images in the image forming units 30Y to 30K in accordance with the conveyance of the paper 11, but adjusts the toner image formation in the image forming units 30Y to 30K. By carrying the sheet 11, the image forming speed can be increased, the remaining amount of the sheet in the sheet feeding cassette 12 can be accurately determined, and the image forming unit 30Y can be determined according to the remaining amount of the sheet 11. Controlling the formation of the toner image at ~ 30K, the paper 11 has run out,
It is possible to prevent the toner images formed on the photoconductor drums 31Y to 31K of the image forming units 30Y to 30K from being wasted. As a result, it is possible to improve the usability of the color image forming apparatus 1 and improve the effective use of resources while improving the processing speed.

4 and 5 are views showing a second embodiment of the remaining paper amount detecting apparatus and the image forming apparatus of the present invention, and FIG. 4 is the remaining paper amount detecting apparatus and the image forming apparatus of the present invention. Color image forming apparatus 7 to which the second embodiment of the apparatus is applied
It is a block block diagram of the control system of 0.

The present embodiment is applied to a color image forming apparatus similar to the color image forming apparatus 1 of the first embodiment, and in the description of this embodiment, the first embodiment will be described. The same components as those of the color image forming apparatus 1 according to the embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 4, a color image forming apparatus 70 is provided.
Are the CPU 50, the ROM 51, the RAM 52, the head drive units 53a to 53d, the print heads 33Y to 33K, the motor / actuator drive unit 54, the high-voltage power supply unit 55, which are the same as those in the color image forming apparatus 1 of the first embodiment. The sensor 56, the sensor signal processing units 57 to 59, the image processing device 60, and the sheet sensor 71 and the sheet remaining amount sensor 72 are provided.

Paper sensor 71 and paper remaining amount sensor 72
5 has the same configuration, and as shown in FIG. 5, includes light emitting element portions 71a and 72a and light receiving element portions 71b and 72b, and the sheet sensor 16 and the sheet remaining amount sensor 1 of the first embodiment.
Similar to the case of 8, the light emitting diode D is used as the light emitting element.
1 is used as a light receiving element and a photodiode D2 is used.

In the light emitting element parts 71a and 72a, the resistor R1 is connected to the light emitting diode D1, but the transistor Tr of the resistor R1 and the light emitting diode D1 is connected, and the transistor Tr constitutes a constant current circuit. The current flowing through the light emitting diode D1 is adjusted.

That is, to the base of the transistor Tr, the light emission amount signal Vi indicating the light emission amount is input from the D / A converter (not shown) of the CPU 50, and the current (diode current) Id flowing through the light emitting diode D1 is I.
d = Vi / R1. Therefore, the emitted light amount signal Vi
The larger the value, the larger the diode current Id and the larger the amount of light emission (light emission power) of the light emitting diode D1.

In the light receiving element portions 71b and 72b, the photodiode D2 is connected to the negative input terminal of the amplifier AMP, and is connected to the positive input terminal of the amplifier AMP, similarly to the light receiving element portions 16b and 18b of the first embodiment. , Comparison voltage V
ref has been entered. A resistor R2 is connected between the output terminal and the negative input terminal of the amplifier AMP, and is connected in parallel to the resistor R2 and the photodiode D.
A resistor R3 connected in series with 2 is connected. The photodiode D2 generates a photocurrent Ip according to the amount of received light, is current-voltage converted by the amplifier AMP, and is output to the sensor signal processing circuits 58 and 59 as an analog output S.

Also in the case of the present embodiment, the light emitting diode D1 and the light receiving element portion 7 of the light emitting element portions 71a and 72a are also included.
The light emission distributions of the photodiodes 1b and 72b and the spectral sensitivity are matched.

The output voltage S of the amplifier AMP is S
= Vref−R2 × Ip, and the difference voltage between the comparison voltage Vref and the output voltage S becomes a value proportional to the amount of received light.
However, the comparison voltage Vref is a reference voltage for keeping the operating point of the output S within an appropriate range.

Color image forming apparatus 70 of the present embodiment
When a plurality of sheets of paper 11 are stacked, or when the attenuation of light becomes large depending on the paper thickness and the transmitted light cannot be detected with sufficient accuracy, the CPU 50 causes the emitted light amount signal V
By adjusting i, the light emitting diodes D of the light emitting element portions 71a and 72a of the paper sensor 71 and the paper remaining amount sensor 72 are adjusted.
The amount of light emitted from the light emitting diode D1 can be changed by adjusting the diode current Id flowing through the LED 1.

Therefore, the light emission amount of the light emitting diode D1 of the light emitting element portions 71a, 72a of the paper sensor 71 and the paper remaining amount sensor 72 is adjusted according to the number and thickness of the paper 11 to improve the detection accuracy. Therefore, the remaining amount of paper can be detected more accurately.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

[0081]

According to the remaining paper amount detecting device of the invention described in claim 1, the remaining paper amount detecting sensor has a light emitting element and a light receiving element which are arranged so as to sandwich the paper placed in the paper tray. When detecting the remaining amount of paper in the paper tray based on the amount of light received from the light emitting element that passes through the paper and is received by the light receiving element, the paper is conveyed from the paper tray to the image forming position on the paper conveyance path. A paper sensor having a light emitting element and a light receiving element is arranged with the light emitting element and the light receiving element sandwiching the conveyed paper, and the light receiving element is transmitted through the paper emitted from the light emitting element of the paper sensor and conveyed. The light transmissivity per sheet is calculated from the amount of light received by the light receiving device and the amount of light received by the light receiving device emitted from the light emitting element in the absence of the paper, and based on the light transmittance per sheet. , Paper remaining amount inspection Since the remaining amount of paper in the paper tray is detected from the amount of light received by the light receiving element of the sensor, the transmissivity of each type of conveyed paper is detected for various types of paper and The remaining amount of paper can be detected, and the remaining amount of paper can be accurately detected regardless of the type of paper.

According to the sheet remaining amount detecting device of the second aspect of the invention, the light emission amount of the sheet remaining amount detecting sensor and the light emitting element of the sheet sensor is based on the light transmittance per sheet detected by the sheet sensor. It is possible to prevent the amount of light received by the light receiving element from becoming insufficient depending on the type of paper, and it is possible to detect the remaining amount of paper more accurately by always performing detection processing with a sufficient amount of light. it can.

According to the image forming apparatus of the third aspect of the present invention, the developing unit forms an electrostatic latent image on the photosensitive member that is rotationally driven, and then toner is attached to form a toner image. The toner image of is transferred to the intermediate transfer belt at the primary transfer position, is conveyed from inside the paper tray, is detected by the registration sensor, is timing adjusted by the registration roller, and is conveyed to the secondary transfer position. Along with transferring the transferred toner image, the paper remaining amount detection sensor having a light emitting element and a light receiving element sandwiching the paper in the paper tray emits light from the light emitting element, transmits the paper, and receives light from the light receiving element. When detecting the remaining amount of paper in the paper tray based on the amount of received light, the image is formed in the developing section regardless of whether the registration sensor detects the paper and the paper tray is used. A paper sensor having a light emitting element and a light receiving element is arranged on the paper transporting path of the paper transported from the inside to the registration roller with the light emitting element and the light receiving element sandwiching the transported paper. The light transmittance per sheet is calculated from the amount of light received by the light receiving element after passing through the paper that is emitted from the light emitting element and conveyed and the amount of light received by the light receiving element that is emitted from the light emitting element without the paper. Then, based on the light transmittance per sheet, the remaining amount of paper in the paper tray is detected from the amount of light received by the light receiving element of the remaining paper amount detection sensor, and the developing unit based on the detected remaining amount of paper. Image formation is controlled, the remaining amount of paper is accurately detected, and the image formation in the developing unit is controlled by the remaining amount of paper, so that the image is formed without the paper being conveyed in the conveyance path and toner is generated. Wasted in vain Can be prevented, it is possible to avoid waste of resources, thereby improving the usability.

According to the image forming apparatus of the fourth aspect of the invention, the light emission amount of the paper remaining amount detection sensor and the light emitting element of the paper sensor is adjusted based on the light transmittance per sheet detected by the paper sensor. Therefore, it is possible to prevent the amount of light received by the light receiving element from becoming insufficient depending on the type of paper, and always perform detection processing with a sufficient amount of light to detect the remaining amount of paper more accurately and It is possible to appropriately reduce waste of resources and further improve the usability.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a color image forming apparatus to which a first embodiment of a sheet remaining amount detecting apparatus and an image forming apparatus of the present invention is applied.

FIG. 2 is a block configuration diagram of a control system of the color image forming apparatus of FIG.

FIG. 3 is a circuit configuration diagram of the paper sensor and the paper remaining amount sensor of FIG.

FIG. 4 is a block configuration diagram of a control system of a color image forming apparatus to which the second embodiment of the sheet remaining amount detecting apparatus and the image forming apparatus of the present invention is applied.

5 is a circuit configuration diagram of the paper sensor and the paper remaining amount sensor of FIG.

[Explanation of symbols]

1 Color image forming device 10 Paper feeder 11 sheets 12 paper cassettes 13 Pickup roller 14 Conveyor rollers 15 Registration roller 16 Paper sensor 16a Light emitting element section 16b Light receiving element section 17 Registration sensor 18 Paper remaining sensor 18a Light emitting element section 18b Light receiving element section 20 Transfer belt mechanism 21 Intermediate transfer belt 22-24 transport rollers 30Y, 30M, 30C, 30K Imaging unit 31Y-31K photoconductor drum 32Y to 32K charging section 33Y to 33K print head 34Y-34K Development unit 35Y-35K transfer part 36Y-36K Cleaning section 40 Secondary transfer section 50 CPU 51 ROM 52 RAM 53a to 53d Head drive unit 54 Motor / actuator drive 55 High-voltage power supply 56 Various sensors 57-59 sensor signal processing unit 60 Image processing device D1 light emitting diode D2 photodiode R1 to R3 resistance AMP amplifier 70 Color image forming apparatus 71 Paper sensor 72 Paper remaining amount sensor 71a, 72a Light emitting element section 71b, 72b Light receiving element section Tr transistor

Claims (4)

[Claims] 1. A sheet remaining amount detecting sensor having a light emitting element and a light receiving element, which are arranged with a sheet placed in a sheet tray sandwiched therebetween, and emitted from the light emitting element of the sheet remaining amount detecting sensor. A remaining paper amount detecting device for detecting the remaining amount of the paper in the paper tray based on the amount of light received by the light receiving element after passing through the paper, and is conveyed from the inside of the paper tray to an image forming position. A paper sensor having a light emitting element and a light receiving element is disposed on the paper transporting path of the paper sheet with the light emitting element and the light receiving element sandwiching the transported paper, and the light is emitted from the light emitting element of the paper sensor and is transported. Calculating the light transmittance per sheet from the amount of light received by the light receiving element after passing through the sheet and the amount of light received by the light receiving element that is emitted from the light emitting element without the sheet, Concerned Based on the light transmittance per sheet of paper, the paper remaining amount detection apparatus characterized by detecting the remaining amount of paper the paper tray from the received light amount of said light receiving element of the paper remaining amount detection sensor. 2. The sheet remaining amount detecting device adjusts the light emission amount of the sheet remaining amount detecting sensor and the light emitting element of the sheet sensor based on the light transmittance per sheet detected by the sheet sensor. The remaining paper amount detection device according to claim 1, wherein 3. A developing unit forms an electrostatic latent image on a photosensitive member which is rotationally driven and then attaches toner to form a toner image,
The toner image on the photoconductor is transferred to the intermediate transfer belt at the primary transfer position, conveyed from inside the paper tray, detected by the registration sensor, and adjusted in timing by the registration roller.
A sheet remaining amount detection sensor that transfers the toner image transferred to the intermediate transfer belt to a sheet that is conveyed to the next transfer position and that has a light emitting element and a light receiving element that are arranged with the sheet in the sheet tray interposed therebetween. An image forming apparatus that detects the remaining amount of the paper in the paper tray based on the amount of light received by the light receiving element that is emitted from the light emitting element, passes through the paper, and detects the paper by the registration sensor. Regardless of whether the image is formed in the developing unit or not, a paper sensor having a light emitting element and a light receiving element is provided on the paper conveyance path of the paper conveyed from the inside of the paper tray to the registration rollers as the light emitting element. The light receiving element is arranged so as to sandwich the conveyed paper, and the light receiving element is emitted from the light emitting element of the paper sensor and passes through the conveyed paper. The light transmissivity per sheet is calculated from the amount of light received by the light receiving device and the amount of light received by the light receiving device that is emitted from the light emitting element in the absence of the paper. On the basis of the amount of light received by the light receiving element of the remaining paper amount detection sensor, the remaining amount of paper in the paper tray is detected, and image formation in the developing unit is controlled based on the detected remaining amount of paper. An image forming apparatus characterized by. 4. The image forming apparatus adjusts the light emission amount of the paper remaining amount detection sensor and the light emitting element of the paper sensor based on the light transmittance per paper detected by the paper sensor. An image forming apparatus according to claim 3, wherein: