JPH11258952A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of appropriately controlling image formation processing means depending on the property of transfer paper under all sorts of environment. SOLUTION: This device is made possible to appropriately control paper transfer processing means so as to match the transfer paper under the all sorts of environment, and to improve the image quality and the transport quality of the various kind of transfer paper, when the environment change of the paper transfer processing means is caused by the absolute humidity, even the absolute humidity value is changed by the temp. in the device, by providing the absolute humidity sensor 17 and the absolute temp. sensor 18, further measuring the temp. value by the temp. sensor 18, and correcting the control value based on this temp. measuring value, at the time of controlling the bias voltage applied on a paper transfer roller 10 base on the absolute humidity value detected by the absolute humidity sensor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer for forming an image by an electrophotographic method, and more particularly, to detecting an environmental condition in the apparatus and executing an image forming process based on the result. The present invention relates to an image forming apparatus that controls at least one factor.

[0002]

2. Description of the Related Art It is well known that the transfer quality of transfer paper used in an image forming apparatus such as a copying machine or the like, particularly the transfer performance and separation performance from a photoreceptor, varies significantly depending on the amount of water. I have. It is known that the moisture content of the transfer paper greatly changes depending on the surrounding environment, especially humidity, and affects the strength of the transfer paper. Further, the quality of the developer used in forming an image also changes depending on the humidity, and the image density and the gradation are greatly affected by the environment. In addition, depending on the amount of water in the developer, background contamination may occur. Therefore, in order to prevent such a problem, a sensor for measuring relative humidity or absolute humidity is provided at a place where environmental change in the image forming apparatus becomes a problem, and transfer conditions and development conditions are determined according to the measured values of the sensors. A method of controlling such as is known. Also, at this time, a method of installing and measuring a sensor near the transfer paper in the transfer paper storage unit, or actively evaporating moisture by heating the transfer paper so that the humidity of the transfer paper can be correctly measured. A method of measuring the amount of water and the like are used. (See, for example, JP-A-5-61367, JP-A-5-119622, and JP-A-5-313515.) However, when a moisture sensor is arranged near the transfer paper to measure the moisture content of the transfer paper, the humidity may be reduced. Since the sensor measures humidity in an atmosphere containing moisture evaporated from the transfer paper, the value of the measured humidity may be higher even though the moisture content of the transfer paper has decreased due to evaporation. A phenomenon may occur. In addition, when the humidity sensor detects the amount of water vapor that evaporates by forcibly applying heat to the transfer paper, in order to accurately measure the amount of moisture contained in the transfer paper, the transfer paper must be It is necessary to keep the amount of heat applied to the transfer paper constant.However, there are multiple elements that serve as heat sources in the image forming apparatus, and the amount of heat generated by these heat sources and the environment in which the image forming apparatus is placed change. It is difficult to measure while keeping the applied heat constant. Therefore, means for controlling the amount of heat applied to the transfer paper and correcting the measured value is required. However, it is difficult to control the amount of heat that changes due to various factors and correct the measured value in real time. Therefore, by using the heat of the fixing unit controlled at a constant temperature (mostly about 170 ° C.) to heat the transfer paper, fluctuations in the amount of heat applied to the transfer paper are prevented,
There has been proposed a method for measuring the humidity of a water vapor atmosphere generated from transfer paper when the paper passes through a fixing unit. In this method, it is necessary to quickly detect the humidity of the water vapor atmosphere evaporating from the transfer paper being moved.
A semiconductor type absolute humidity sensor of a heat conduction type that responds in a short time of 1 second or less even in an atmosphere of ° C is employed.

[0003]

However, sensors for measuring the moisture content of the transfer paper must be installed inside the image forming apparatus, and the humidity changes due to the temperature change inside the apparatus. That is, as shown in FIG. 9, the absolute humidity changes depending on the temperature, and the higher the temperature, the greater the degree of the change. For this reason, it is difficult to accurately grasp the state of the transfer paper, especially the amount of water, and appropriately control the image forming process in accordance with the characteristics of the transfer paper. Further, when the transfer paper is heated to evaporate water to measure the amount of water, the heating may change the characteristics of the transfer paper, that is, so-called breakage detection. Accordingly, an object of the present invention is to provide an image forming apparatus capable of appropriately controlling an image forming process unit in accordance with the characteristics of a transfer sheet under any environment.

[0004]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a plurality of environmental value measuring means, one of which includes one or more environmental value measuring means. The environmental conditions are calculated based on the values, and the image bearing unit, the charging process unit, the latent image forming process unit, the developing process unit, the transfer paper conveying unit, the transfer process unit, and the fixing process unit are calculated according to the calculated environmental condition. , Static elimination process means, etc., at least one factor of the image forming process means comprising a series of process means for forming an image by electrophotography, for example, a bias voltage value applied to a transfer roller serving as a transfer means, transfer paper The image forming the image while controlling the paper feed roller pressure value, the transfer paper transport speed in the transfer paper transport unit and the fixing unit, the charging current value by the charging unit In the forming apparatus, when controlling at least one factor of the image forming process means, the environment value is further measured by one or more environment value measuring means of the plurality of environment value measuring means. Is characterized in that the control value is corrected based on According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, at least one of the plurality of environmental value measuring units is a sensor for measuring an absolute humidity, One is a sensor for measuring temperature. According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, absolute humidity measurement data by a sensor for measuring the absolute humidity and temperature measurement data by a sensor for measuring the temperature are provided. Is used to calculate an environmental value, and the control value is corrected according to the calculation result. According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, at least one of the plurality of environmental value measuring means is a sensor for measuring humidity, and at least one of the other environmental value measuring means is a sensor for measuring humidity. One is a sensor for measuring temperature, and the control value of at least one factor of the transfer process means forming a part of the image forming process means is temporarily determined based on humidity measurement data by the sensor for measuring humidity. Set, start control based on the provisionally set control value, perform temperature measurement with a sensor for measuring the temperature, and correct the provisionally set control value based on the temperature measurement data at this time. It is characterized by doing so. According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the control value is a bias voltage value applied to the transfer process unit.

[0005]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an internal perspective front view of an image forming apparatus showing an example of an embodiment of the present invention, and FIG. 2 is a schematic front view showing a main part of the image forming apparatus shown in FIG.
In this example, a configuration of a color copying machine is shown as an example of an image forming apparatus. The color copier 100 includes a color scanner unit 20, a color printer unit 30,
The paper feed unit 40 includes an image processing unit (not shown) and the like. The color scanner unit 20 converts the image of the original (O) on the contact glass 20a into the illumination lamp 2
0b, the mirror group 20c, and the lens 20d, form an image on the color sensor 20e, and read an image of the original (O), for example, blue (Blue), green (Green).
n), read for each color separation light of red (Red), and convert to electrical signals. Based on the color separation image signal intensity levels of blue (Blue), green (Green), and red (Red) obtained by the color scanner unit 20, a color change process is performed by an image processing unit (not shown).
Color image data of black, cyan, magenta, and yellow is obtained. This image signal is converted into an optical signal in the color printer unit 30, and optical writing corresponding to the read image of the original (O) is performed by a laser beam through the polygon mirror 30a, the f / θ lens 30b, and the reflection mirror 30c. Then, an electrostatic latent image is formed on the surface of the image carrier 1 that has been uniformly charged by the charging device 7.
A plurality of different colors formed on the image carrier 1 (photoreceptor drum) rotating in the direction of arrow A shown in the figure, namely, black, cyan, magenta (Ma)
, and a plurality of developing devices (black) 2a, a developing device (cyan) 2b, a developing device (magenta) 2c, and a developing device (magenta) arranged at predetermined intervals. The development is performed by a development unit (developing process means) 2 composed of yellow (2d).

[0006] Intermediate transfer belt 3 receiving the transfer of each developed image
Is stretched around a belt transfer roller 4, a tension roller 5, and a belt driving roller 6a facing the image carrier 1. The belt is driven to rotate by the driving unit 6 via the belt driving roller 6a, 7 is configured so as to come into contact with and separate from the image carrier 1 by the contacting / separating operation of the image carrier 1. This image forming apparatus includes, for example, Bk,
A switchback method is employed to prevent the transfer positions of the C, M, and Y images from being shifted. The switchback method is
After the intermediate transfer belt 3 is rotated in the forward direction and brought into contact with the image carrier 1, the first color toner image on the image carrier 1 is transferred onto the intermediate transfer belt 3. Next, the image carrier 1
, The intermediate transfer belt 3 is separated, and rotated in the return direction by an amount corresponding to the rotation in the forward direction, so that the transfer position of the second color toner image is adjusted. By repeating this operation four times, an image is formed on the intermediate transfer belt 3. The transfer paper (P) in which the four-color superposed color toner image formed on the intermediate transfer belt 3 is fed and conveyed from the paper feed unit 40 and synchronously fed by the registration roller pair 30e.
Is transferred by a paper transfer roller (transfer process means) 10. Immediately downstream of the paper transfer roller 10, a separation charger 12 for separating the transfer paper (P) from the intermediate transfer belt 3 and the paper transfer roller 10 is provided. The transfer paper P on which the four-color superimposed color toner image has been transferred is fixed to a fixing unit (fixing process means) 11 by a transport unit 30f.
After the toner image is fused and fixed by the fixing roller pair 11a, the sheet is discharged by the discharge roller pair 30d and stored on a discharge tray (not shown). In the above-described series of image forming processes, the toner remaining on the surface of the image carrier 1 is appropriately cleaned and removed by the photoconductor cleaning unit 8, and the toner remaining on the intermediate transfer belt 3 is appropriately cleaned and removed by the belt cleaning unit 9. You.

FIG. 3 is a partially enlarged view showing a main part of the image forming apparatus of FIG. In the figure, 13 is a manual feed table,
The intermediate transfer belt 3, which is a developing position, and the paper transfer roller 1 from the manual feed table 13 via the registration roller pair 30e.
A guide plate 19, an intermediate roller 15, and the like, which are located near the lower side of the transport path 14 that transports the transfer paper P to the nip portion of the transfer paper P and guide the transfer paper P fed from the paper feed unit 40 to the transport path 14, A humidity sensor 17 for measuring absolute humidity and a temperature sensor 1
8 are arranged vertically adjacent to each other. This position is
The transfer paper P is the position most affected by the surrounding environment,
In addition, it is a position that is not easily affected by the environment inside the apparatus. The reason why the humidity sensor 17 and the temperature sensor 18 are arranged close to each other as described above is that it is difficult to uniformly and accurately measure the humidity value in the image forming apparatus due to measurement technology. That is, there are heat sources such as the fixing unit 11 at various places in the image forming apparatus and an air flow for ozone and toner recovery processing is formed. This is because the temperature greatly changes depending on the temperature. As the humidity sensor 17 and the temperature sensor 18, an accurate thermistor type sensor having high measurement accuracy is used.

In this embodiment, an absolute humidity sensor capable of directly detecting an absolute humidity value is used as the humidity sensor 17 for convenience of calculating environmental conditions. However, the absolute humidity value is measured using a humidity sensor for measuring relative humidity. When obtaining the absolute humidity value, the absolute humidity value at "100% RH" corresponding to the measured value of the temperature is obtained from the graph of FIG. 9, and is multiplied by the relative humidity value. Therefore, an approximate expression for obtaining the absolute humidity value at “100% RH” corresponding to the measured value of the temperature is created, and this is stored in the ROM of the control unit of the image forming apparatus. However, if the absolute humidity value is calculated from the relative humidity value using this approximate expression, a relative humidity sensor that is less expensive than the absolute humidity sensor can be sufficiently substituted. In particular, when the relative humidity value is dominant as in the case of the charging unit 7 and the developing unit 2, the environmental conditions may be calculated using an inexpensive relative humidity sensor.

FIG. 4 shows a configuration of a control mechanism of the image forming apparatus according to this embodiment. In the figure, reference numeral 21 denotes a CPU provided in a control unit of the image forming apparatus. The CPU 21 receives an absolute humidity value from the humidity sensor 17 and a temperature value from the temperature sensor 18 and executes a predetermined control program. Charging charger 7, developing unit 2, belt transfer roller 4,
Control signals are output to the respective elements constituting the image forming process means of the image forming apparatus, such as the paper transfer roller 6a. In particular, by executing a fuzzy operation described later using the absolute humidity value from the humidity sensor 17 and the temperature value from the temperature sensor 18, a control value corresponding to the water content of the transfer paper P is obtained, and this is transferred to the paper transfer. It is output as a control signal for the roller 10. This control signal is generated by the bias power supply 22 for about 1
The pressure is increased to 000 times and applied to the paper transfer roller 10.
At this time, as illustrated in FIG. 5, the fuzzy calculation is performed such that the bias voltage applied to the paper transfer roller 10 changes complicatedly according to the water content of the transfer paper P and greatly fluctuates depending on environmental conditions. . Therefore, the intermediate transfer belt 3
In a paper transfer process in which the transfer performance from the paper varies in a complicated manner depending on the amount of water in the transfer paper P and greatly varies with the temperature, when controlling the bias voltage, which is a control factor, the environmental conditions, It is most effective to obtain a control value by fuzzy calculation in consideration of a change in absolute humidity due to the change. By using this method,
It is possible to easily match the water content of the transfer paper P with the absolute humidity value obtained from the humidity sensor 17.

As described above, when controlling the bias voltage which is a control factor of the paper transfer roller 10 which is one of the image forming process means based on the absolute humidity value from the humidity sensor 17, the temperature sensor 18 further controls the bias voltage. The temperature is measured, and the control value is corrected based on the temperature value. In other words, in this example, the control value is obtained by fuzzy calculation in consideration of a change in absolute humidity due to a temperature change. The paper transfer process can be appropriately controlled in accordance with the characteristics of (1). Therefore, it is not necessary to use a method of forcibly evaporating water by heating the transfer paper to measure the amount of water, so that the destruction detection as described in the description of the related art does not occur. The charge removing unit 12 illustrated in FIG. 4 removes the charge on the transfer paper P after transfer by an amount not affected by the toner, and discharges (peel discharge) during the subsequent conveyance and fixing process.
This is provided to prevent the occurrence of a phenomenon that adversely affects the image such as Further, as a result of examining the relationship between an appropriate current value flowing through the paper transfer roller 10 and the water content of the transfer paper P, it was confirmed that the appropriate current value was constant regardless of environmental conditions. However, since it is necessary to consider the compatibility with various types of transfer paper, the voltage value is controlled according to environmental conditions as shown in FIG. Also, since the relationship between environmental conditions and the moisture content of the transfer paper is not clear and it is difficult to formulate it, it is difficult to formulate the relationship. The various coefficients in the formula are determined in consideration of the operating conditions of each process unit of the image forming apparatus.

As shown in FIG. 6, a fuzzy control block is provided in the CPU 21 and a humidity sensor 1 is provided.
7 and the temperature value from the temperature sensor 18 are input to a fuzzy control block, where a fuzzy operation is performed in accordance with a membership function relating to the absolute humidity value and the temperature value, whereby the transfer paper P A control value corresponding to the water content is obtained, and this is output as a bias voltage control signal. FIG. 7 is an explanatory diagram illustrating a membership function in the fuzzy control according to the present embodiment, and FIG. 8 is an explanatory diagram illustrating a fuzzy rule (rule). The image forming apparatus of this embodiment performs a process control by executing a fuzzy operation according to these membership functions and fuzzy rules. Hereinafter, the operation at that time will be described. The image forming apparatus enters the measurement mode a predetermined time after the main power is turned on, inputs the absolute humidity value from the humidity sensor 17 and the temperature value from the temperature sensor 18 to the fuzzy control block, and sends the absolute value to the paper transfer roller 10. Find the control signal. Thereafter, measurement is performed at intervals of, for example, 30 minutes, and a control value of 通常 of the normal control value is output prior to the next process execution.
However, it is prohibited to enter the measurement mode during the execution of the process means of the image forming apparatus and for one hour after the execution is stopped.

The absolute humidity value and temperature value input to the CPU 21 are expressed as membership values of the respective membership functions shown in FIG. By taking the lower value of this membership value (minimum operation), the membership value of the bias control signal is obtained according to the rule of FIG. Similarly, the membership values of the bias control signals are obtained for all the conditions, the value with the highest membership value (max operation) of each membership function is selected as the membership value of the function, the union is taken, and the center of gravity is calculated. Find points. The bias control signal value at this time is the control value to be obtained. Then, the bias control signal of this control value is amplified to about 1000 times the voltage by the bias power supply 22 and applied to the paper transfer roller 10 as described above. At this time, the CPU 21 controls the bias power supply 22 so that the bias power supply 22 is turned on immediately before the transfer paper P enters the transfer position to apply a bias voltage to the paper transfer roller 10 and turned off immediately after passing the transfer position. I do. In the above embodiment, the control value at the time of control is obtained by fuzzy calculation. However, a bias voltage control value to be applied to the paper transfer roller 10 is temporarily set based on humidity measurement data by the humidity sensor 17, and The control is started based on the temporarily set control value, the temperature is measured by the temperature sensor 18, and the temporarily set control value is corrected based on the temperature measurement data at this time. The transfer conditions can be appropriately controlled according to the characteristics of the transfer paper, and the image quality and transport quality of various transfer papers can be improved.
In the above embodiment, the case where the bias voltage of the paper transfer roller 10 is controlled as the control factor of the image forming process unit has been described as an example. However, other control factors, for example, the feed roller pressure value of the transfer paper P Transfer paper transfer speed in the fixing unit 11, charging current value by the charging unit 7,
Various factors such as the operation timing of the static elimination unit 12 can be controlled. Further, in the above embodiment, the case where the present invention is applied to a digital copying machine has been described. However, the present invention is not limited to this, and can be applied to an analog copying machine. Further, the present invention can be applied to a digital multifunction peripheral having both functions of a digital copying machine and functions of a printer device and a facsimile device.

[0013]

As described above, the present invention has the following excellent effects. According to the first aspect of the present invention, when at least one control factor of the image forming process unit is controlled by an environment value measured by one or more environment value measurement units, one or more environment factors are further controlled. Since the environmental value is measured by the value measuring means and the control value is corrected based on the environmental value, the image forming process means can be appropriately controlled according to the characteristics of the transfer paper under all environmental conditions, and various Image quality and transfer quality of the transfer paper can be improved. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, at least one of the plurality of environmental value measuring means is a sensor for measuring absolute humidity, and at least one of the other environmental value measuring means is a sensor for measuring absolute humidity. First, because it is a sensor for measuring temperature, it is necessary to measure absolute humidity as an environmental value to control a control factor, and when this absolute humidity fluctuates due to the temperature inside the device, By measuring the temperature inside the device, the control value based on the absolute humidity can be corrected based on this measured value, so that the image forming process means can be appropriately controlled according to the characteristics of the transfer paper under all environmental conditions As a result, image quality and transport quality of various transfer papers can be improved. According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the absolute humidity measurement data by the sensor for measuring the absolute humidity and the temperature measurement data by the sensor for measuring the temperature are used. The environmental value is calculated in accordance with the calculation result, and the control value is corrected in accordance with the calculation result. Therefore, the environmental change of the image forming process means is caused by the absolute humidity, and the absolute humidity value is changed by the temperature in the apparatus. Therefore, the environmental values for controlling the control factors can be accurately and stably calculated, and the control values are corrected in accordance with the calculation results, so that the image can be adjusted in accordance with the characteristics of the transfer paper under all environmental conditions. The formation process means can be appropriately controlled, and the image quality and transport quality of various transfer papers can be improved.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, at least one of the plurality of environmental value measuring means is a sensor for measuring humidity, and the other is a sensor for measuring humidity. At least one is a sensor for measuring temperature, and a control value of at least one factor of a transfer unit which forms a part of the image forming process unit is temporarily set based on humidity measurement data by the sensor for measuring humidity. Then, control is started based on the provisionally set control value, temperature is measured by a sensor for measuring the temperature, and the provisionally set control value is corrected based on the temperature measurement data at this time. By doing so, it is possible to appropriately control the transfer means according to the characteristics of the transfer paper under all environmental conditions, and to improve the image quality and transport quality of various transfer papers It can be. According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, by controlling a bias voltage value applied to a transfer roller serving as the transfer unit as a control factor, transfer is performed under all environmental conditions. The transfer means can be appropriately controlled in accordance with the characteristics of the paper, and the transfer efficiency at the time of transfer on various transfer papers can be improved, and image quality can be improved by suppressing the occurrence of loose images and the like.

[Brief description of the drawings]

FIG. 1 is an internal perspective front view of an image forming apparatus showing an example of an embodiment of the present invention.

FIG. 2 is a schematic front view showing a main part of the image forming apparatus shown in FIG.

FIG. 3 is a partially enlarged view showing a main part of the image forming apparatus of FIG. 1;

FIG. 4 is a configuration diagram of a control mechanism of the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is a fuzzy control characteristic diagram illustrating conditions for applying a bias voltage to a paper transfer roller according to the water content of the transfer paper.

FIG. 6 is a main part configuration diagram of a control mechanism shown in FIG. 4;

FIG. 7 is an explanatory diagram illustrating a membership function in fuzzy control according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating a fuzzy rule according to the embodiment of this invention.

FIG. 9 is a diagram illustrating a change characteristic of an absolute humidity depending on a temperature.

[Explanation of symbols]

Reference Signs List 1 image carrier, 2 developing device (developing process means), 3
Intermediate transfer belt, 4 belt transfer roller, 6a belt drive roller, 8 photoconductor cleaning unit, 9 belt cleaning unit, 10 paper transfer roller (transfer process means), 11 fixing unit (fixing process means), 12 separation charger, 14 transport Path, 16
Transport route, 17 humidity sensor, 18 temperature sensor, 20
Color scanner unit, 20e color sensor, 2
1 CPU, 22 bias power supply, 30 color printer unit, 30f transport unit, 40 paper feed unit, 100 color copier (image forming apparatus), O original, P transfer paper.

Claims (5)

[Claims] An environmental condition is calculated based on environmental values measured by one or a plurality of environmental value measuring means, and image forming is performed in accordance with the calculated environmental conditions. In an image forming apparatus which forms an image while controlling at least one factor of a process unit, when controlling at least one control factor of the image formation process unit, the image forming apparatus further includes one of the plurality of environment value measuring units. Alternatively, an image forming apparatus is characterized in that an environment value is measured by a plurality of environment value measurement means, and a control value is corrected based on the environment value. 2. At least one of the plurality of environmental value measuring means is a sensor for measuring absolute humidity,
The image forming apparatus according to claim 1, wherein at least one other is a sensor for measuring a temperature. 3. An environmental value is calculated using absolute humidity measurement data by a sensor for measuring the absolute humidity and temperature measurement data by a sensor for measuring the temperature,
3. The image forming apparatus according to claim 2, wherein the control value is corrected according to a result of the calculation. 4. At least one of said plurality of environmental value measuring means is a sensor for measuring humidity, at least one other is a sensor for measuring temperature, and measuring said humidity. Tentatively setting the control value of at least one control factor of the transfer processing means forming a part of the image forming process means based on the humidity measurement data by the sensor for the purpose, and starting the control based on the tentatively set control value. The method according to claim 1, wherein a temperature measurement is performed by a sensor for measuring the temperature, and the control value set temporarily is corrected based on the temperature measurement data at this time. Image forming device. 5. The method according to claim 4, wherein the control value is a bias voltage value applied to the transfer processing unit.
An image forming apparatus according to claim 1.