JP4096148B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention develops an electrostatic latent image formed on an image carrier with toner of a developing device, detects the remaining amount of toner in the developing device with a toner remaining amount detecting means, and the remaining amount of toner is a predetermined value. The present invention belongs to the technical field of an image forming apparatus in which toner is replenished into the developing device when the amount is smaller.
[0002]
[Prior art]
Conventionally, various types of image forming apparatuses in which toner is supplied to the developing device when the toner amount in the developing device is reduced have been manufactured. Especially, a toner cartridge containing toner has been replaced. Many image forming apparatuses that supply toner by doing so are manufactured. The remaining amount of toner in the developing device is detected when the remaining amount of toner in the developing device is detected by a toner remaining amount detecting means such as a dot count method or a toner density sensor, and the result of the detection is that the remaining amount of toner is less than a predetermined value. In addition, toner is supplied to the developing device. In this specification, the detection of the remaining amount of toner in the developing device includes a case where the remaining amount of toner in the developing device is predicted.
[0003]
Incidentally, the toner used in the image forming apparatus is formed of powder. In general, this powder has an appropriate particle size distribution, and its volume average particle size is as small as about 10 μm or less. Therefore, it is impossible to manage the physical properties (particle size, shape, composition, charge amount, etc.) of each toner particle so as to be the same. For this reason, the toner supplied into the developing unit can be a toner that is easily developed on the image carrier and a toner that is difficult to develop. For example, in a one-component developer, a toner having a relatively small particle diameter is generally easily developed and a toner having a relatively large particle diameter is hardly developed. As a result, the toner having a large particle diameter tends to remain in the developer. It is said.
[0004]
Therefore, as the amount of toner in the developing device decreases, a relatively large amount of toner remaining in the developing device is gradually used for development, so that the image has a rough feeling, The image quality will deteriorate.
[0005]
This will be described with reference to FIGS. 2 (a) and 2 (b). In FIG. 2A, the degree of change in image quality with respect to the remaining amount of toner in the developing device when the first cartridge is inserted into the developing device (initial state of the apparatus) is indicated by a solid line in the drawing. That is, as the amount of toner in the developing device decreases, the ratio of toner having a relatively large particle diameter increases in the toner in the developing device, so that the image quality gradually deteriorates as shown in FIG. . However, even when the remaining amount of toner in the developing device becomes smaller than the toner replenishment setting value indicating the replenishment of new toner (the toner remaining amount value indicated as “end” in the figure), the image quality is maintained within the allowable value. The The end of the toner replenishment set value indicates the replacement timing of a new cartridge, that is, the replenishment timing of new toner.
[0006]
When the cartridge is replaced with a new second cartridge in this state, the small particle size toner supplied from the second cartridge is selectively developed again, so the image quality is indicated by a one-dot chain line in FIG. As shown, the image quality is restored to a level close to the first solid line. However, since the ratio of the toner having a relatively large particle diameter in the developing unit is clearly increased from the first one, the supply of the toner having the large particle size to the developing unit becomes earlier than the first one, and the amount of toner in the developing unit is increased. When image quality decreases, the degree of deterioration of image quality is fast.
[0007]
When the remaining amount of toner in the developing device becomes smaller than the toner replenishment set value and the nth (n ≧ 3) th cartridge is replaced, immediately after the replacement of the nth cartridge, the replenishment is performed as described above. Since the toner having a small particle size is also selectively developed, the image quality is restored to a level close to the solid line. However, at this time, the ratio of the toner having a relatively large particle diameter is increasing in the toner in the developing device, so that the image quality does not return to the solid line level. Furthermore, as the cartridge replacement progresses, the ratio of toner having a relatively large particle diameter increases more and more, so the degree of image quality deterioration becomes faster and larger when the remaining amount of toner decreases. Finally, even if a predetermined amount or more of toner remains, the image quality is not acceptable.
In FIG. 2A, the near end is a state in which image quality deterioration starts to become relatively large, that is, a state in which the toner in the developing device has decreased and the toner replenishment time (the cartridge replacement time in the case of a toner cartridge) is approaching. (The same applies to the near end in the other figures).
[0008]
Further, depending on the image forming apparatus, there is an image forming apparatus in which the remaining amount of toner in the developing device becomes extremely small at the end of the toner, and the ratio of the toner having a relatively large particle diameter is extremely increased. . In such an image forming apparatus, as shown by a solid line in FIG. 2B, even in the first cartridge, the image quality becomes an acceptable image quality just before the toner end. In such an image forming apparatus, the amount of residual toner in the developing device is minimized at the end of the toner and the ratio of the toner having a relatively large particle size is extremely increased. Therefore, even when the nth (n ≧ 2) th cartridge is replaced, the deterioration of the image quality as described above is small and close to the first level as shown by the dotted line in FIG. It will be a thing.
[0009]
In this way, in an image forming apparatus that replenishes new toner by replacing the cartridge when toner in the developing device runs out, the small particle size toner that is easily developed in the new cartridge is used for development, thereby improving image quality. Figured.
[0010]
[Problems to be solved by the invention]
However, in an image forming apparatus in which a toner cartridge is replaced while leaving a relatively large amount of toner, as the number of cartridge replacements increases, the ratio of toner having a relatively large particle diameter increases in the toner in the developing device. Therefore, (1) The degree of return of the image quality is gradually deteriorated by replacing the cartridge. (2) When the toner in the developing device is reduced, the degree of image quality deterioration that occurs is accelerated. (3) The toner end is reached. There is a problem that an unacceptable image quality is generated before.
In addition, in an image forming apparatus in which a toner cartridge is replaced with relatively little toner remaining, an acceptable image quality is generated just before the toner end even in the first cartridge, and even if a new cartridge is replaced, it is relatively early. However, there is a problem that the image quality becomes unacceptable.
[0011]
The present invention was made in view of such problems, and its object is to provide an image forming apparatus capable of deterioration of graininess of images even when many replenishment number of toner having Rukoto to suppress Wins That is.
[0012]
In order to solve this problem, the invention of claim 1 is provided such that a toner cartridge is replaceably provided in the developing device, and the electrostatic latent image formed on the image carrier is developed with toner of the developing device, and in the image forming apparatus to which the toner cartridge is turned so that is exchanged when the toner remaining amount has become rather less than the toner replenishment setting value indicating a supply time of new toner, detecting the remaining amount of toner in the developing device Toner remaining amount detecting means, means for indicating that the toner remaining amount is less than the toner replenishment set value, means for counting the number of replacement of the toner cartridge, and the number of replacement of the toner cartridge are set. And a control means for increasing the toner replenishment setting value when the threshold value is reached .
[0014]
[Action]
In the image forming apparatus according to the first aspect of the present invention configured as described above, the toner cartridge replacement time is changed to be earlier as the number of replacements of the toner cartridge increases, and the image of the second aspect of the present invention is further changed. In the forming apparatus, when the number of replacement of the toner cartridge reaches a predetermined number and the remaining amount of toner in the developing device reaches a predetermined amount, the replacement time of the toner cartridge is changed. Thereby, deterioration of the rough feeling of an image is suppressed.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing an example of an embodiment of an image forming apparatus according to the present invention.
[0022]
As shown in FIG. 1, the image forming apparatus 1 in this example is the same as a conventionally known full-color image forming apparatus. However, in brief, the image to be formed is uniformly charged. The exposed photosensitive member 2 is exposed as an electrostatic latent image. Next, the electrostatic latent image on the photosensitive member 2 is sequentially (by toner of each color of the non-magnetic one-component developing units 3, 4, 5, 6 of yellow, magenta, cyan, and black in a rotary developing device ( The order of each color is arbitrary), and the color of each color is adjusted and developed while the photoreceptor 2 rotates once for each color, and a toner image is obtained. The photosensitive member 2 (corresponding to the image carrier of the present invention) 2 rotates to send the toner image on the photosensitive member 2 toward the transfer unit 7, and the transfer roller 7 a of the transfer unit 7 transfers the paper. A fixed image (desired image) is obtained on the paper 8 by being transferred to the paper 8 conveyed by the conveying means and then fixed by the fixing device 9.
[0023]
After the toner image is transferred onto the paper 8, the residual toner remaining on the photoreceptor 2 is removed by the cleaning blade 10a of the cleaning device 10 and collected in the residual toner box. In that case, the cleaning blade 10a is set to a position where the residual toner is not cleaned until the transfer of the toner image to the paper 8 is completed, and the residual toner is cleaned when the transfer to the paper 8 is completed. The residual toner is removed by setting the position. When the residual toner removal is completed, the position is set so that the cleaning is not performed again, so that the color matching of each color toner on the photoreceptor 2 is not hindered.
[0036]
In the image forming apparatus 1 of this example, the image forming apparatus 1 is configured as a conventionally known image forming apparatus that uses a toner cartridge and supplies toner by replacing the toner cartridge. As in the prior art, the remaining amount of toner in each of the developing devices 3, 4, 5, and 6 is detected by the dot count method or by the remaining toner detecting means such as a toner density sensor, and the remaining toner is detected. Based on the result, when the remaining amount of toner becomes less than the toner replenishment setting value, that is, when it is time to replace the toner cartridge, a new toner cartridge of that color is replaced. The corresponding developing devices 3, 4, 5, and 6 are replenished.
[0037]
In this case, in the image forming apparatus 1 of this example, the above-described toner replenishment setting value of the remaining amount of toner is changed according to the number of replacements of the toner cartridge, that is, the replacement timing of the toner cartridge is changed. More specifically, the toner cartridge is changed so that the number of replacements of the toner cartridge is increased and the above-mentioned toner replenishment setting value of the toner remaining amount is increased , that is, the replacement timing of the toner cartridge is changed earlier. The change of the toner replenishment setting value, that is, the change of the toner cartridge replacement time may be performed every time the toner cartridge is replaced, or a plurality of toner cartridge replacement threshold values are set and the number of toner cartridge replacements is set. You may make it carry out in steps with respect to increase of.
[0038]
As described above, the replacement timing of the toner cartridge is advanced as the number of replacements of the toner cartridge increases, so that it is possible to suppress the deterioration of the roughness of the image. In this case, even if a new toner is replenished by replacing the toner cartridge, the large-diameter toner remains in the developing device. The effect cannot be obtained.
[0039]
Further, in this example, the toner remaining amount is determined based on the number of replacement of the toner cartridge and the detection result of the toner remaining amount in the developing device by the dot count method or the toner remaining amount detecting means such as the toner density sensor. The toner replenishment set value, that is, the toner cartridge replacement time is changed. In that case, when the number of replacements of the toner cartridge reaches a predetermined number and the remaining amount of toner becomes a discarded patch formation setting value set separately, the above-described toner replenishment setting value of the remaining amount of toner is changed so as to increase. In other words, the replacement timing of the toner cartridge can be changed earlier.
[0040]
The image forming apparatus of the present invention is not limited to the image forming apparatus in the above example, and detects the remaining amount of toner in the developing device and develops toner when the remaining amount of toner is less than the toner replenishment set value. The image forming apparatus can be applied to any image forming apparatus as long as it is replenished in the container.
[0041]
【The invention's effect】
As apparent from the above description, according to the image forming apparatus of the invention of claim 1, modified to faster time to replace the toner cartridge according to frequency of replacing the toner cartridge is increased, further, claim 2 According to the image forming apparatus of the invention, the toner cartridge replacement time is changed so as to be advanced when the toner cartridge replacement count reaches a predetermined number and the remaining amount of toner in the developing device reaches a predetermined amount. It becomes possible to suppress the deterioration of the rough feeling of the image.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating an example of an embodiment of an image forming apparatus according to the present invention.
FIG. 2A is a developing device in a conventional image forming apparatus in which a predetermined amount of toner remains even at the end of the toner, and the state of image quality depending on the amount of toner in the developing device and the number of toner replenishment times increase. FIG. 6B is a view similar to FIG. 5A in the case of a conventional image forming apparatus in which the remaining amount of toner in the developing device becomes minimal when the toner end is reached . .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photoconductor (image carrier) 3, 4, 5, 6 ... Developing device, 7 ... Transfer device, 8 ... Paper, 9 ... Fixing device, 10 ... Cleaning device, 10a ... Cleaning blade

Claims (1)

A toner cartridge is replaceably provided in the developing unit, and the electrostatic latent image formed on the image carrier is developed with the toner of the developing unit, and the toner replenishment setting value indicating the toner replenishment timing when the remaining amount of toner is new In the image forming apparatus in which the toner cartridge is replaced when the toner cartridge becomes less,
Toner remaining amount detecting means for detecting the remaining amount of toner in the developing device, means for indicating that the toner remaining amount is less than the toner replenishment setting value, means for counting the number of replacements of the toner cartridge, An image forming apparatus comprising: control means for increasing the toner replenishment set value when the number of replacement times of the toner cartridge reaches a set threshold value.

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