JPH0746241B2 - Temperature correction device in automatic image density control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a temperature correction device in an automatic image density control device, and more specifically, based on the ambient temperature of a photoconductor, the exposure amount, the development bias, or the like is determined. The present invention relates to a temperature correction device that corrects a control amount of image forming conditions.

<Prior Art> Conventionally, for the purpose of improving the usability of a copying machine, an automatic exposure device for controlling an image forming condition, particularly an exposure amount, or a developing bias in accordance with a document density has been mounted.

More specifically, when the original density is high or low, the exposure amount or the developing bias is decreased,
Alternatively, it is known that by increasing the exposure amount or the developing bias, it is possible to prevent the occurrence of electric charge loss, fog, etc., and obtain a copy having an appropriate density. Such control is automatically performed. An automatic image density control device is mounted for this purpose.

However, even if the exposure amount or the developing bias is changed based on only the document density as described above, even if the same amount of light is irradiated on the photoconductor itself, the surface of the photoconductor is not changed. Since the rate of charge removal changes depending on the temperature (hereinafter simply referred to as “surface temperature”),
It is necessary to change not only the original density but also the exposure amount or the developing bias based on the surface temperature.

On the other hand, if the surface temperature is directly detected by the temperature sensor, the surface of the photoconductor may be damaged.

Therefore, in consideration of these points, conventionally, a temperature sensor is attached in the vicinity of the photoconductor to detect the ambient temperature of the photoconductor (hereinafter, simply referred to as “ambient temperature”), and the surface temperature is The entire range that may change is estimated from the detected ambient temperature and the temperature is corrected.
Specifically, assuming that the relationship between the change range of the ambient temperature and the change range of the surface temperature is almost constant over the entire range, the correction amount is updated by updating the correction amount each time the ambient temperature changes by a certain range. Is applied. That is, the ambient temperature range in which the correction is performed with the same correction amount is uniform over the entire range.

<Problems to be Solved by the Invention> However, in the above temperature correction device, accurate correction corresponding to the surface temperature characteristic of the photoconductor cannot be performed, and there is no compensation for obtaining a copy having an appropriate density. There is a problem.

More specifically, as shown in FIG. 5, the surface temperature characteristics of the selenium-based photosensitive drum are gradually different from the atmospheric temperature that changes linearly with time when the temperature is relatively low, as shown in FIG. It changes like a curve to stand up. Therefore, when the temperature is relatively low, the lower the temperature, the more gradual the change in the surface temperature with respect to the change in the ambient temperature. More specifically, when the temperature is relatively low, at a certain temperature, for example, when the ambient temperature changes by 5 ° C., the surface temperature becomes 1 ° C.
Even if it changes, at a lower temperature, the surface temperature changes only 0.5 ° C when the ambient temperature changes 5 ° C. That is, when the temperature is relatively low, even if the correction amount is updated in response to a change in the ambient temperature within a certain range, the surface temperature actually changes so much that the correction amount needs to be updated. Absent.

Further, as described above, from the viewpoint of protecting the surface of the photoconductor, since the temperature sensor is attached close to the photoconductor to detect the ambient temperature, the actual surface temperature of the photoconductor and the temperature detected by the temperature sensor are Will be considerably deviated as shown in FIG. In particular, inside the copying machine, the temperature detected by the temperature sensor fluctuates considerably due to convection of air and the like even if the surface temperature is constant.

Therefore, under such a circumstance, if temperature correction is performed so that the same amount of ambient temperature is corrected over the entire range, the temperature correction cannot be performed properly, and the copy obtained on the contrary is obtained. There is a problem that the image quality of the object is deteriorated.

<Objects of the Invention> The present invention has been made in view of the above problems,
An object of the present invention is to provide a temperature correction device in an automatic image density control device capable of performing a proper temperature correction corresponding to the surface temperature of a photoconductor to obtain a copy having an appropriate density.

<Means for Solving the Problems> To achieve the above object, a temperature correction device of the present invention includes a temperature detecting means for detecting an ambient temperature of a photoconductor, and a photosensing device based on a detection signal from the temperature detecting means. A determination unit that determines whether the ambient temperature of the body is within a predetermined range that does not require temperature correction, is higher than the upper limit value of the predetermined range, or is lower than the lower limit value of the predetermined range, and the determination unit. If it is determined that the ambient temperature of the photoconductor is higher than the upper limit value of the above-mentioned predetermined range, the image forming condition is set so that the temperature range in which the same amount of correction is performed is kept substantially constant. The control amount of is corrected according to the temperature,
When it is determined that the ambient temperature of the photoconductor is lower than the lower limit value of the above-mentioned predetermined range, the image forming condition is controlled so that the temperature range in which the same amount of correction is performed becomes wider as the temperature decreases. And a correcting means for correcting the quantity corresponding to the temperature.

In the temperature correction device having the above-described configuration, the ambient temperature of the photoconductor is detected by the temperature detecting means when the image forming conditions are controlled to detect the document density and obtain the proper copy density.
When the ambient temperature of the photoconductor is detected, the detected ambient temperature of the photoconductor is within a predetermined range that does not require temperature correction,
Alternatively, it is determined whether the value is larger than the upper limit value of the predetermined range or less than the lower limit value of the predetermined range.

As a result, when it is determined that the ambient temperature of the photoconductor is within a predetermined range that does not require temperature correction, the image forming condition is controlled based on only the document density.

Further, when it is determined that the ambient temperature of the photoconductor is higher than the upper limit value of the predetermined range, the control amount of the image forming condition is controlled so that the temperature range in which the same amount of correction is performed is kept substantially constant. A correction corresponding to the temperature is made. Here, such control is performed by the relationship between the variation width of the ambient temperature of the photoconductor and the variation width of the surface temperature of the photoconductor when the ambient temperature of the photoconductor is higher than the upper limit value of the predetermined range. Is almost constant.

Further, when it is determined that the ambient temperature of the photoconductor is lower than the lower limit value of the predetermined range, the control amount of the image forming condition is adjusted so that the temperature range in which the same amount of correction is performed becomes wider as the temperature decreases. Is corrected according to the temperature. Here, such control is performed when the ambient temperature of the photoconductor is lower than the lower limit value of the predetermined range, the lower the ambient temperature of the photoconductor is, the more the ambient temperature of the photoconductor changes. This is because the change in the surface temperature of the photoconductor becomes gentle. That is, when the ambient temperature is lower than the lower limit value of the predetermined range, even if the correction amount to be applied to the control amount of the image forming condition is updated in response to the change of the ambient temperature by a certain range, the exposure This is because the body surface temperature has not changed so much that the correction amount needs to be updated.

As described above, according to this temperature correction device, when the ambient temperature of the photoconductor is within a predetermined range where temperature correction is not required, the image forming condition is controlled based only on the document density, and If the ambient temperature is outside the predetermined range that does not require the temperature correction, the relationship between the variation range of the ambient temperature of the photoconductor and the variation range of the surface temperature of the photoconductor is not only the density of the document but also the ambient temperature of the photoconductor. Since the image forming conditions are controlled in consideration of the difference depending on whether it is relatively high or low, it is possible to obtain a copy having an appropriate density regardless of the surface temperature of the photoconductor.

Also, since the image forming conditions are controlled by detecting the ambient temperature of the photoconductor, the surface of the photoconductor can be protected.

<Example> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating an example.

FIG. 4 is a schematic view showing a main part of the copying machine, which has an exposure lamp (3) for exposing a document (2) set on the document table (1) and also has a document table (1 ), A charging charger (5), a surface potential sensor (6), a developing device (7), a transfer charger (8), and a separation charger () around the photosensitive drum (4) of a serene tellurium system. 9), a cleaner (10), and a thermistor (11) are arranged in this order. Then, the copy paper is guided between the photoconductor drum (4) and the transfer charger (8) through the copy paper transport unit (12) and separated from the photoconductor drum (4) by the separation charger (9). Is conveyed toward the fixing device (15).

FIG. 1 is a block diagram showing the electrical configuration of the automatic image density control device, which shows the output signal from the surface potential sensor (6),
And the output signal from the thermistor (11) is not shown in A /
The signal is supplied to the microcomputer (13) via the D converter and the I / O interface, and the control signal from the microcomputer (13) is supplied via the I / O interface (not shown) and the D / A converter. It is supplied to the exposure lamp lighting circuit (14), and the output voltage signal from the exposure lamp lighting circuit (14) is applied to the exposure lamp (3).

FIG. 2 is a flow chart for explaining the operation of the automatic image density control device having the above construction.

After initializing the copying machine, warming up, and the like in steps not shown, the original (2) is illuminated by supplying a predetermined voltage set in advance to the exposure lamp (3) in the step, and the photosensitive drum in the step. The potential of the electrostatic latent image formed on the surface of (4) is detected by the surface potential sensor (6), the ambient temperature of the photoconductor drum (4) is detected by the thermistor (11) in step, and the thermistor ( It is determined whether or not the detection temperature T ° C in 11) is within a preset predetermined temperature range (T1 ° C <T ° C <° C).

If it is determined in the step that T1 ° C <T ° C <T2 ° C, in the step, as shown by the area A in FIG. Based on this, the applied voltage is changed to the exposure lamp (3), and the copying operation is performed with the applied voltage changed in the step to obtain a copy having an appropriate density.

If it is determined that T ° C <T1 ° C in the above step, the voltage applied to the exposure lamp (3) is changed based on the document density in the step, and
In the step, as indicated by a region B in FIG. 3, the voltage applied to the exposure lamp (3) is changed so that the temperature range in which the same amount of correction is performed becomes wider as the temperature lowers. . Here, such control is performed when the ambient temperature T ° C. of the photosensitive drum (4) is less than the lower limit value T1 ° C. of the preset predetermined temperature range. This is because the lower the ambient temperature T ° C., the more gradual the change in the surface temperature of the photosensitive drum (4) with respect to the change in the ambient temperature T ° of the photosensitive drum (4). That is, when the ambient temperature T ° C. of the photosensitive drum (4) is less than the lower limit value T ° C. of the predetermined temperature range, exposure is performed in response to the ambient temperature T ° C. of the photosensitive drum (4) changing by a certain range. This is because even if the correction amount of the applied voltage of the lamp (3) is updated, the surface temperature of the photosensitive drum (4) does not actually change so much that the correction amount needs to be updated.

Then, step processing is performed.

Furthermore, when it is determined that T2 ° C. <T ° C. in the above step, the voltage applied to the exposure lamp (3) is changed based on the original density in the step, and in the step, the area C in FIG. As shown by, the voltage applied to the exposure lamp (3) is changed so that the temperature range in which the same amount of correction is performed is kept substantially constant. Here, such control is performed because the variation range of the ambient temperature T ° C. of the photosensitive drum (4) and the variation range of the surface temperature of the photosensitive drum (4) are substantially constant.

Then, step processing is performed.

The temperatures T1 and T2 ° C are 28 and
The temperature is 40 ° C., and in this temperature range, the actual surface temperature of the photosensitive drum (4) is approximately 20 to 25 ° C., and there is no need to perform temperature correction. However, since there is a possibility of fluctuation of about several degrees Celsius depending on the type of the photoconductor drum (4) actually used, the arrangement of each constituent member inside the copying machine, etc., the temperature T1, It is preferable to be able to change T2 ° C.

In summary, the ambient temperature T ° C. of the photosensitive drum (4) detected by the thermistor (11) is T1 ° C. <T ° C.
Within the range of <T2 ° C., the voltage applied to the exposure lamp (3) is controlled based on only the original density.

If the ambient temperature T ° C. of the photosensitive drum (4) is out of the above range, not only the document density but also the variation range of the ambient temperature T ° C. of the photosensitive drum (4) and the photosensitive drum (4).
The voltage applied to the exposure lamp (3) is controlled in consideration of the fact that the relationship with the variation range of the surface temperature of the exposure lamp (3) differs depending on whether the ambient temperature T ° C. of the photosensitive drum (4) is higher or lower than the above range. It

Therefore, regardless of the surface temperature of the photosensitive drum (4), it is possible to obtain a copy having an appropriate density.

Note that the present invention is not limited to the above-described embodiment. For example, instead of controlling the voltage applied to the exposure lamp (3), the developing bias supplied to the developing device (7) is controlled, and the surface potential sensor is controlled. Instead of detecting the document density by (6), the document density can be directly detected based on the reflected light from the document, and the thermistor (11) is arranged at the charging charger (5) and the cleaner (10). ), And the developing bias can be controlled while exposing the original instead of exposing the entire surface of the original to control the exposure amount or the developing bias. In addition, various design changes can be made without departing from the scope of the present invention.

<Effects of the Invention> As described above, according to the present invention, when the ambient temperature of the photoconductor is within a predetermined range that does not require temperature correction, the image forming condition is controlled based only on the document density, and When the ambient temperature of the photoconductor is out of the predetermined range where the temperature correction is not required, not only the document density but also the relationship between the variation range of the ambient temperature of the photoconductor and the variation range of the surface temperature of the photoconductor is shown. Since the image forming conditions are controlled in consideration of the fact that the ambient temperature of 1 is different depending on whether it is relatively high or low, it is possible to obtain a copy having an appropriate density regardless of the surface temperature of the photoconductor.

Further, since the image forming conditions are controlled by detecting the ambient temperature of the photoconductor, the surface of the photoconductor can be protected.

[Brief description of drawings]

FIG. 1 is a block diagram showing the electrical configuration of the automatic exposure apparatus of the present invention, FIG. 2 is a flow chart for explaining the automatic exposure operation, FIG. 3 is a diagram showing temperature correction characteristics, and FIG. FIG. 5 is a schematic diagram showing the parts, and FIG. 5 is a diagram showing the relationship between the actual temperature of the photosensitive drum and the temperature detected by the temperature sensor. (3) ... exposure lamp, (4) ... photosensitive drum, (7) ... developing device, (11) ... thermistor, (13) ... microcomputer

Continuation of front page (56) Reference JP-A-57-181562 (JP, A) JP-A-57-84463 (JP, A) JP-A-63-55575 (JP, A) JP-A-58-127948 (JP , A) JP-A-58-123568 (JP, A) JP-A-52-96032 (JP, A) Actually developed JP-A-57-172459 (JP, U)

Claims (1)

[Claims] 1. An automatic image density control device for controlling an image forming condition to detect an original density and obtain an appropriate copy density, and a temperature detecting means for detecting an ambient temperature of a photoconductor and a detection signal from the temperature detecting means. Based on the
Within a predetermined range that does not require temperature correction, or larger than the upper limit value of this predetermined range, or less than the lower limit value of the predetermined range, a determination means, and the result of the determination by this determination means, When it is determined that the ambient temperature of the photoconductor is higher than the upper limit value of the above-mentioned predetermined range, the temperature is set to the control amount of the image forming condition so that the temperature range in which the same amount of correction is performed is kept almost constant. When the corresponding correction is performed and it is determined that the ambient temperature of the photoconductor is less than the lower limit value of the above-described predetermined range, the temperature range in which the same amount of correction is performed becomes wider as the temperature decreases. A temperature correction device in an automatic image density control device, comprising: a correction unit that performs a correction corresponding to a temperature on a control amount of an image forming condition.