JPH06258902A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device which can adjust an image forming condition or the handling condition of a paper by precisely grasping temperature and relative humidity in the device and form an image with a stable density without making the device large in size and expensive. CONSTITUTION:Plural thermometers 2-1, 2-2, 2-3, 2-4 and 2-5 and a hygrometer 3 are provided at proper positions in the image forming part 1 of the image forming device. Besides, an arithmetic means 11 calculating the relative humidity of the respective parts from the information of the temperature and the information of the relative humidity obtained by the thermometer and the hygrometer and a control means 5 setting the image forming condition or the like according to the information of the relative humidity obtained by the arithmetic means 4 are provided in the device. Thus, the proper image forming condition is adjusted at any time according to the change of an environmental condition such as the temperature or the humidity and the image with the stable density is obtained.

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 for irradiating a photosensitive member with image light so that toner is adhered to a formed electrostatic latent image to make it visible, and in particular, temperature information measured in the apparatus. And an image forming apparatus that controls image forming conditions and the like that affect image density based on relative humidity information.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus, there is known an apparatus which irradiates an image light onto a photoconductor to form an electrostatic latent image, and transfers an image visualized by adhesion of toner onto a sheet. There is. The density of an image formed in such an image forming apparatus is easily affected by environmental conditions such as temperature and humidity.

FIG. 4 is a graph showing the relationship between the relative humidity of the paper tray portion and the transfer efficiency of the toner image onto the paper when the charging current of the transfer charger is kept constant in the image forming apparatus. It is a thing. In this figure, it is shown that the transfer efficiency of the toner image onto the paper changes greatly as the relative humidity changes. This makes the image density on the paper unstable. FIG. 5 shows the relationship between the relative humidity of the transfer area and the releasability of the paper from the transfer drum when the charging current of the peeling charger is constant. In this figure, it is shown that when the relative humidity of the transfer area is low, the peeling property of the paper is poor and the paper jam easily occurs. Further, FIG. 6 shows the relationship between the relative humidity of the toner supply region and the chargeability of the developer. In this figure, it is shown that the higher the relative humidity in the toner supply area, the lower the chargeability of the developer. When the chargeability of the developer is low, the toner is likely to adhere to the electrostatic latent image on the photoconductor and the development density increases. That is, a change in relative humidity causes a change in image density.

As described above, the image density and the handling condition of the paper are changed due to the change of the environment in the apparatus, but the temperature, the humidity and the like in the apparatus are not only the condition of the outside air, but also the duration of use of the image forming apparatus, the formation It also changes depending on the usage conditions such as the content of the image to be displayed. For this reason, in order to always form an image under appropriate conditions and with appropriate density, the environment inside the device is continuously monitored and the charging current of the charger or transfer charger that uniformly charges the photoconductor is used. Image forming conditions such as the developing bias voltage applied to the developer carrier, or the light amount of the writing device,
Alternatively, the paper handling conditions such as the charging current of the peeling charger must be adjusted appropriately. Especially in a color image forming apparatus, there is a great need for such adjustment.

Under the circumstances as described above, an image forming apparatus for changing image forming conditions and the like according to the environment has been conventionally proposed, for example, Japanese Patent Laid-Open Nos. 63-177177 and 63-177178. Kaisho 1-31905
There is one disclosed in Japanese Patent No. 4 publication. All of these conventional image forming apparatuses measure the environment at one place in the apparatus and try to adjust the image forming conditions and the like based on the measurement.

[0006]

However, when the image forming apparatus is continuously used, there may be a large temperature difference in the apparatus, which causes a large difference in the relative humidity. FIG. 3 shows the results of measuring the temperature and the relative humidity at three locations in the image forming apparatus, and the measurements were made for three cases in which the conditions of the outside air were different. As shown in these figures, it is shown that a large difference in temperature and relative humidity occurs depending on the position in the apparatus as the usage state of the image forming apparatus changes. For this reason, if a plurality of image forming conditions or paper handling conditions are adjusted based only on the environmental conditions measured at one place in the device, an error due to the difference in the environment inside the device is large, and an appropriate adjustment cannot be made. There is a problem that you cannot do it. This tends to have a stronger influence in a larger image forming apparatus.

On the other hand, it is also possible to measure the temperature and the relative humidity at a plurality of positions in the image forming apparatus and adjust a plurality of image forming conditions based on the measured values. However, since the external dimensions of the humidity measuring device are relatively large and the durability is limited, it is necessary to periodically replace the humidity measuring device. Therefore, providing a plurality of temperature measuring devices and a plurality of humidity measuring devices in the image forming apparatus increases the size of the apparatus and increases the cost and maintenance cost of the apparatus. The present invention has been made in view of the above problems, and an object thereof is to form an image by grasping the temperature and relative humidity in the image forming apparatus without increasing the size and cost of the apparatus. An object of the present invention is to provide an image forming apparatus capable of forming an image by adjusting the conditions or the handling conditions of the paper and always keeping the density and the handling of the paper stable.

[0008]

In order to solve the above-mentioned problems, the present invention irradiates a photoreceptor with image light and attaches toner to the formed electrostatic latent image to form a toner image. In an image forming apparatus for transferring and fixing an image, a plurality of thermometers provided at different positions in the image forming apparatus,
Absolute humidity from the hygrometer provided at a position close to one of the plurality of thermometers, and temperature information and relative humidity information obtained by the thermometer and the hygrometer provided close to each other. Calculating means for calculating relative humidity from this absolute humidity and temperature information obtained by another thermometer, and image formation that affects image density based on a plurality of relative humidity information obtained by the calculating means. Control means for controlling the conditions or the handling conditions of the paper.

Further, in the image forming apparatus according to the first aspect, it is preferable that the hygrometer is incorporated in a unit in which the humidity sensing section and the amplification calibration section can be exchanged.

The image forming conditions that affect the image density are
Select a plurality of conditions from the light amount when irradiating image light, the charging current when uniformly charging the photoconductor, the bias voltage applied between the photoconductor and the developing roll, the charging current for transfer, etc. be able to. Further, the handling conditions of the paper include the charging current of the peeling charger and the like.

[0011]

In the image forming apparatus having the above-described structure, a plurality of thermometers are provided at different positions in the apparatus, and a hygrometer is provided at a position close to one of the plurality of thermometers. Therefore, the temperature at a plurality of locations in the device and the relative humidity at a position close to the one thermometer can be accurately measured at any time. Further, the absolute humidity can be calculated from the temperature information and the relative humidity information obtained by the thermometer and the hygrometer provided at the close positions. Further, since the absolute humidity shows the same value in the device, it is possible to accurately grasp the relative humidity at other plural points in the device from the value of the absolute humidity and the temperature information obtained by other thermometers. it can. It has been confirmed again by the measurement results shown in FIG. 3 that the absolute humidity in the image forming apparatus, that is, the amount of water in the air is constant under a steady installation atmosphere.
Further, since the control means for controlling the image forming conditions based on the plurality of pieces of relative humidity information obtained by the calculating means is provided, the image forming conditions or the paper handling conditions are adjusted at any time to make the image density uniform. A good copy image can be obtained.

Further, by using the hygrometer in which the humidity sensitive section and the amplification calibration section are incorporated in a replaceable unit, calibration when replacing the hygrometer becomes unnecessary. Generally, a hygrometer is inferior in durability to a thermometer and often needs to be replaced, but due to the above, the maintainability of the device is significantly improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an image forming apparatus which is an embodiment of the present invention. In this image forming apparatus, a photosensitive drum 19 on which an electrostatic latent image is formed on the surface by irradiating the image forming unit 1 with image light from a writing device 17 after being uniformly charged, and the photosensitive drum 19. A charging device 16 for uniformly charging the surface, a developing device 18 for visualizing an electrostatic latent image on the photosensitive drum 19, a developer supplying section 30 for supplying a developer to the developing device 18, a paper tray 31, A paper feeding device 33 for taking out the paper from the paper 32, a transfer device 14 for transferring the toner image from the photosensitive drum 19 to the paper supplied from the paper feeding device 33, and a paper for which the toner image is transferred is separated from the transfer drum 34. It comprises a peeling device 15 and a fixing device 35 for fixing the toner image on the paper by applying pressure and heat. Further, the image forming apparatus includes a developing bias power source 8 for applying a bias voltage between the developer carrying member 38 installed in the developing device 18 and the photosensitive drum 19,
9, 10, 11 and the transfer device 14, peeling device 15,
A transfer device power supply 12, a peeling device power supply 13, a charging device power supply 6 for supplying currents to the charging device 16, and a light amount adjusting device 7 for adjusting the light amount of the image light emitted from the writing device 17 are provided. ing.

In the image forming section 1, thermometers 2 _-1 , 2 _-2 and a hygrometer 3 are provided near the developer supply section 30.
And thermometers 2 _-3 , 2 _-4 , and 2 _-5 are arranged near the peeling device 15, the fixing device 35, and the paper tray 32. Further, the thermometers 2 _-1 , 2 _-2 are provided in the device. 2 _-3 , 2 _-4 , 2 _-5
And a calculation device 4 for calculating the relative humidity of each part from temperature information and relative humidity information obtained by the hygrometer 3, and image forming conditions or handling of paper based on the relative humidity information obtained by the calculation device 4. A control device 5 for controlling the conditions is provided.

The thermometers 2 _-1 , 2 _-2 are installed at two different locations near the developer supply unit 30 for separately storing the four color toners. The thermometer 2 _-1 is
As shown in FIG. 2, the support column 2 provided on the attachment member 21.
The hygrometer 3 is attached to the support plate 22 supported by the thermometer 2 _-1, and the hygrometer 3 is provided at a position close to the thermometer 2 _-1.
It is supported by being attached to the No. 4 unit. This hygrometer 3 has a humidity sensing section and an amplification calibration section incorporated in one unit, and can be replaced with the connection plug 24 for replacement. Further, a temperature IC is used to detect the temperature of the thermometer 2 _-1 , and is provided close to the hygrometer 3 within a range that does not interfere with the humidity detection. Other thermometers 2 _-2 , 2
_-3 , 2 _-4 and 2 _-5 have the same structure as the thermometer 2 _-1 . In FIG. 2, reference numeral 25 is the thermometer 2 _−1.
And a connection terminal for connecting the signal line from the hygrometer.

The arithmetic unit 4 calculates the absolute humidity from the temperature information and the relative humidity information obtained by the thermometer 2 _-1 and the hygrometer 3 which are provided close to each other. Assuming the same value at each position, calculate the relative humidity at a certain position of each thermometer from this value and the temperature information obtained by other thermometers 2 _-2 , 2 _-3 , 2 _-4 , 2 _-5 . Is.

Based on the humidity information obtained by the arithmetic unit 4, the control unit 5 supplies the developing bias power supplies 8, 9 ,.
10, 11, transfer device power supply 12, peeling device power supply 1
3. It controls the applied voltage in the charging device power source 6 and the light amount adjusting device 7. That is, the bias voltage applied between the photoconductor drum 19 and the developer carrying member 38 from the developing bias power sources 8, 9, 10, 11 is changed based on the relative humidity near the developer supplying section. The charging current controlled and supplied from the power source for the transfer device to the transfer device 14 is controlled so as to change depending on the relative humidity near the paper tray. Further, the charging current supplied from the peeling device power supply 13 to the peeling device is controlled so as to change based on the relative humidity near the transfer device. Similarly, the control device controls the charger power supply 6 and the light amount adjusting device 7 so that the charging current of the charging device for uniformly charging the photosensitive member and the light amount when the image light is irradiated from the writing device 17 to the photosensitive drum 19 are changed. To control. The arithmetic unit 4 and the control unit 5 may be a microcomputer equipped with a storage device.

Next, the operation of the image forming apparatus of this embodiment will be described. The storage environment of the developer stored in the developer supply unit is sequentially monitored by thermometers 2 _-1 , 2 _-2 and a hygrometer 3 provided near the developer supply unit. Thermometer 2
_-1 and the temperature and relative humidity analog signals from the thermometer 3 are A / D converted, 12 measurements are taken every 20 ms, and the average value excluding the maximum and minimum values is stored in the microcomputer. Stored in the storage device. Such measurements can be set for 10-120 min or 50-1000
Rewrite the contents at intervals of one sheet. It should be noted that the interval between the humidity information and the temperature information can be set individually, and by setting these values according to the installation atmosphere, measurement with less error can be performed. Further, the absolute humidity is calculated by the arithmetic unit 4 from the average value of the temperature and the relative humidity obtained by the thermometer 2 _-1 and the hygrometer 3, and the absolute humidity and other thermometers 2 _-2 , 2 The relative humidity at a certain position of each thermometer is calculated from the temperatures obtained by _-3 , 2 _-4 , and 2 _-5 .

Of the measurement data thus obtained, based on the measurement data in the vicinity of the developer supply section, the light amount correction coefficient of the writing device and the development of the photosensitive drum are read from the table set in the storage device in advance. The potential contrast, the correction value of the developing bias, and the like are obtained, and the control device 5 controls the developing bias power sources 8, 9, 10, 11, the charging device power source 6, and the light amount adjusting device 7. Thereby, an appropriate contrast potential corresponding to the relative humidity can be obtained, and the image density can be appropriately maintained. Further, the relative humidity in the vicinity of the transfer area, the vicinity of the fixing device, the vicinity of the paper tray, etc. is obtained, and based on this value, the charging current flowing from the power supply 12 for the transfer device to the transfer device 14 from the table preset in the storage device. The charging current supplied from the peeling device power supply 13 to the peeling device 15 is controlled by the control device 5. By controlling as described above, the image forming conditions and the paper handling conditions are adjusted according to the environment of each part in the apparatus, and image formation such as transfer, peeling and fixing is always performed under appropriate conditions.

In this embodiment, since the humidity sensor 3 and the amplification calibration unit are incorporated in a replaceable unit, the hygrometer 3 is used. Only removal and installation eliminates the need for calibration, greatly improving maintainability.

[0021]

As described above, in the image forming apparatus of the present invention, the relative humidity of each part is calculated from the temperature and relative humidity measured at one location in the apparatus and the temperatures measured at other multiple locations. Since the image forming condition or the paper handling condition that influences the image density is controlled based on this, it is not necessary to provide humidity measuring devices at a plurality of places in the device, and a highly accurate image can be obtained with a simple configuration. It is possible to adjust the forming conditions or the paper handling conditions. As a result, it is possible to always form an image with a stable image density without being affected by changes in environmental conditions such as temperature or humidity and without causing troubles such as paper jams.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus that is an embodiment of the present invention.

FIG. 2 is a schematic front view and a schematic side view showing a hygrometer / thermometer mounting unit used in the above embodiment.

FIG. 3 is a diagram showing changes in relative humidity, absolute humidity, and temperature in the image forming apparatus according to usage conditions, FIG.
FIG. 6B and FIG. 6B are diagrams showing the results of measurement in a state where the temperature and humidity of the outside air are different.

FIG. 4 is a diagram showing a relationship between relative humidity of a paper tray unit and transfer efficiency.

FIG. 5 is a diagram showing a relationship between relative humidity in a transfer area and peelability of a sheet from a transfer drum.

FIG. 6 is a diagram showing a relationship between relative humidity in a toner supply region and developer charging property.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Thermometer 3 Hygrometer 4 Computing device 5 Control device 6 Power supply for charging device 7 Light intensity adjusting device 8, 9, 10, 11 Power supply for developing bias 12 Power supply for transfer device 13 Power supply for peeling device 14 Transfer device 15 Peeling device 16 Charging device 17 Writing device 18 Developing device 19 Photosensitive drum 20 Thermometer / hygrometer mounting unit 30 Developer supply section 31, 32 Paper tray 33 Paper feeding device 34 Transfer drum 35 Fixing device

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[Procedure amendment]

[Submission date] November 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 is a diagram showing changes in relative humidity, absolute humidity, and temperature in the image forming apparatus according to usage conditions, FIG.
Figures (b) and (c) are diagrams showing the results of measurement in a state where the temperature and humidity of the outside air are different.

Claims (2)

[Claims] 1. An image forming apparatus for irradiating a photoconductor with image light, adhering toner to a formed electrostatic latent image to form a toner image, and transferring and fixing the toner image, the image forming apparatus comprising: A plurality of thermometers provided at different positions, a hygrometer provided at a position close to one thermometer of the plurality of thermometers, and a thermometer and a hygrometer provided close to each other Calculate the absolute humidity from the obtained temperature information and relative humidity information,
A calculating means for calculating the relative humidity from the absolute humidity and the temperature information obtained by another thermometer, and an image forming condition or a paper condition that affects the image density based on the plurality of relative humidity information obtained by the calculating means. An image forming apparatus, comprising: a control unit that controls a handling condition. 2. The image forming apparatus according to claim 1, wherein the hygrometer is incorporated in a unit in which a humidity sensitive section and an amplification calibration section are replaceable.