JP2003228227A - Toner depletion detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus or a toner depletion detecting device constituted so that toner depletion is stably and accurately detected, decreasing or eliminating influence exerted by environment. <P>SOLUTION: Humidity is detected once a day, for example, by a humidity sensor 43 provided in a printer 100, and the detected humidity is stored in a control unit 88. The unit 88 integrates the humidity of ten days, for example, and changes a reference value for judging the toner depletion by referring to a correspondence table based on the sum of the humidity. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner empty detection system in an image forming apparatus, and more particularly to a toner empty detection system capable of detecting stable and accurate toner empty regardless of environmental changes.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, light is emitted according to an image to be formed on the surface of a charged photosensitive drum. Due to this light irradiation, the charged charges on the surface of the photoconductor flow away to the center side of the photoconductor drum, so that the portion irradiated with light and the portion not irradiated with light have different charging states. That is, a latent image is formed on the surface of the photoconductor.
When the charged toner approaches and contacts the surface of the photoconductor drum, the powder toner is electrostatically adsorbed on the charged portion,
It is not adsorbed on non-charged parts.

In this way, a toner image is formed, and this process is development. This toner image is directly (or indirectly, that is, once transferred to a transfer belt, a transfer drum, etc., and then transferred to a recording paper, and the toner transferred to the recording paper is transferred with heat and pressure. Fix on paper (fix). In this way, in the electrostatic image forming apparatus, image formation, that is, printing or copying is performed.

The toner stored in the image forming apparatus is gradually consumed each time development is performed in the above-described developing process, and new toner is supplied when most of the toner is consumed, that is, when the toner empty state is reached. The need arises.

In the case of a liquid, it is possible to easily know the amount of the remaining liquid by detecting the liquid surface position, but as described above, the toner is a powder, and the liquid is naturally flat like the liquid. Since it is not a surface, it is difficult to use this method as it is for detecting toner empty.

One of the toner empty detection methods utilizes the fluidity of the powder, that is, the time when the slope formed of the powder collapses, and the collapse time at this time is related to the amount of powder. It is used to detect. Specifically, when scraping the toner with the rotating blades, the resulting slope will collapse, so the time until the reflected or transmitted light for detection is blocked by the collapsed toner (fall time) is Alternatively, it is detected from the side. When the amount of remaining toner is sufficiently large, there is no time for light to be transmitted or reflected, and as the amount of remaining toner decreases, the time for transmission or reflection appears. Can be detected.

One of other methods is to integrate print information, for example, the area of a toner image to be formed, and calculate the total toner consumption amount from the integrated value and the consumption amount per area obtained in advance. Then, the remaining toner amount is estimated based on this.

[0008]

Even when the other conditions are the same, the image forming apparatus is placed on the fluidity of the toner which is a powder and the amount of the toner which is adsorbed on the photosensitive drum. It changes according to the environment. That is, the fluidity of the toner changes due to changes in the environment, and thus the time during which the toner collapses changes.

However, in the prior art, there is no recognition of this fact, and no countermeasure is taken for it. Therefore, in the former detection method, the reference collapse time as a reference for comparison for this detection falls in the environment. It was set to be constant regardless of. Therefore, the remaining toner amount is not accurately detected, and the toner empty warning is issued or the image forming apparatus is stopped even if the remaining toner amount is still sufficient, or an image with a normal toner remaining amount is displayed. The image forming work was sometimes performed as it was, though it was not enough to form the image.

Further, in the latter method, the fact that the amount of consumption per area obtained in advance depends on the history of the environment and the environment in which it is placed is not considered, and it is treated as a constant value. It was not possible to accurately detect the toner empty.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce or eliminate such an influence from the environment and to enable stable and accurate detection of toner empty in an image forming apparatus.

[0012]

The above-mentioned problems can be solved by the following means. That is, the solution means of the first invention is a first detection means for detecting the remaining amount of toner in the image forming apparatus, a second detection means for detecting the environment to which the toner is exposed, Detection condition changing means for changing the detection condition for the first detection means, and the detection so as to change the detection condition of the first detection means according to the detection result of the second detection means. A toner empty detecting device is provided with control means for controlling the condition changing means.

According to a second aspect of the present invention, there is provided a toner empty detecting device according to the first aspect of the present invention.
The above detection means uses the toner collapse time as the detection condition.

According to a third aspect of the present invention, in the toner empty detecting device according to the first or second aspect of the invention, the image forming apparatus detects the environment exposed to toner detected by the second detecting device. The temperature and / or humidity inside and / or outside the image forming apparatus are used.

According to a fourth aspect of the invention, in the toner empty detecting device of the first to third aspects, the detection result of the second detecting means is an integrated value per predetermined time, or It is an average value.

According to a fifth aspect of the invention, there is provided a first detecting step for detecting the remaining amount of toner in the image forming apparatus, a second detecting step for detecting the environment to which the toner is exposed, And a detection condition control step for changing the detection condition for the detection performed in the first detection step according to the detection result in the second detection step. Is the way.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on Examples. FIG. 1 is a schematic diagram of a central cross section of a printer 100 according to an embodiment. The printer 100 includes a charging device 2, an exposure device 3, an imaging unit 4, a transfer roller 6, a cleaner 7, and the printer as a whole and each component so as to face the photosensitive drum 1 rotating in the direction of the arrow and the surroundings. A control unit 88 for controlling the operation is provided.

The imaging unit 4 comprises a photosensitive drum 1 and a developing unit. The developing unit is provided with a developing roller 41 as described later,
The developing roller 41 faces the photosensitive drum 1.

Below the printer 100, there are provided a loading section for loading cassettes 81 and 82 containing recording paper, and a manual feed tray 83. Cassette 81, 8
2, or an appropriate recording sheet taken out one by one from the manual feed tray 83 is conveyed toward the photoconductor drum 1 by a large number of conveying roller pairs 84. The toner image formed on the photoconductor drum 1 is transferred to the recording paper guided between the photoconductor drum 1 and the transfer roller 6 as described later.
The recording paper on which the toner image has been transferred further moves upward and is guided between the fixing roller pair 85, where heat and pressure are applied, so that the toner image is fixed on the recording paper. The recording paper after fixing is discharged onto the discharge tray 87 by the guide 86.

FIG. 2 is an enlarged view showing the periphery of the photosensitive drum 1 in an enlarged manner. In FIG. 2, the dotted line shows members belonging to the imaging unit 4, and the dotted line shows the printer 10.
0 shows members belonging to the main body. When the toner runs out, the imaging unit 4 is replaced with a new one with the photosensitive drum 1.

At the time of image formation, as the photosensitive drum 1 rotates, the surface of the photosensitive drum 1 that has passed in front of the charging device 2 is charged. When this surface passes in front of the exposure device 3, the surface is scanned with laser light according to the image density.

The electric charges on the surface irradiated with the laser beam flow to the central conductor portion of the photosensitive drum 1 and the electric charges there are lost, while the non-irradiated portions remain charged. Therefore, a charge image (latent image) is formed although it is invisible. When the surface of the photosensitive drum 1 reaches the front of the developing roller 41, the charged toner held on the developing roller 41 is electrostatically adsorbed. Since this attraction is performed according to the charge of the latent image, a visible image (toner image) is formed (that is, developed) on the surface of the photosensitive drum 1 by the toner.

The toner image reaches the transfer roller 6 by the rotation of the photosensitive drum 1, and the toner image is electrostatically transferred onto the recording paper supplied between the photosensitive drum 1 and the transfer roller 6. Then, as described above, the recording paper is conveyed to the fixing roller pair 85 and fixed. On the other hand, the toner remaining on the surface of the photosensitive drum 1 after the toner is transferred is cleaned by the cleaner 7. After that, it reaches the charging device 2 again and is charged, and the same operation is repeated.

The replaceable imaging unit 4 is provided with a developing housing 49. The developing housing 49 is adjacent to a first chamber 49a for storing toner called a toner hopper, and the developing roller 41 is rotatable. It is composed of a second chamber 49b called a developing unit which is supported and housed. The second chamber 49b is composed of the wall of the developing housing 49 and almost half of the developing roller 41.

The developing roller 41 rotates clockwise in the direction of the arrow in FIG. 2, and around the periphery thereof, the photosensitive drum 1, the first regulating blade 51, the second regulating blade 52 and the rotatable replenishment are provided toward the upstream in the rotational direction. A roller 53 and a static eliminator 54 are arranged. These are supported by the developing housing 49 except the photosensitive drum 1.

The replenishing roller 53 conveys the toner in the second chamber 49b toward the developing roller 41 by rotating in a fixed direction. The first regulating blade 51 and the second regulating blade 52 form a thin toner layer on the developing roller 41 and frictionally charge the toner thin layer. The charged toner comes to face the photoconductor drum 1 as the developing roller 41 rotates, and from there, it moves toward the latent image charging section by electrostatic force and is attracted to the photoconductor drum 1. The charge removing unit 54 performs charge removal refresh of the toner remaining on the developing roller 41.

A passage hole 49c communicates between the first chamber 49a and the second chamber 49b. The passage hole 49c is located above the two chambers, and new toner is consumed by the amount consumed in the second chamber 49b through the passage hole 49c.
It is supplied from 9a.

The first window 49a has a light transmitting window 5 on its lower side wall.
6. A reflecting mirror 57 is provided on the upper wall opposed to the reflecting mirror 57, and a rotatable transfer blade 55 is provided substantially at the center of the chamber. This is an arrow (half clock) on the transport blade 55.
The first chamber 49a and its flexibility such that its tip can be deformed along the lower wall of the first chamber 49a when the first chamber 49a rotates.
It has enough rigidity to scrape the toner inside.

The toner in the first chamber 49a is transferred to the conveying blade 55.
As a result of being lifted up by the
up to c. The second chamber 49 passes through the passage hole 49c.
The toner amount consumed in b flows into the second chamber 49b, and the overflowed toner is recirculated to the first chamber 49a again. By this operation, the second chamber is always filled with an appropriate amount of toner.

A light emitting / receiving element 58 is provided directly below the light transmitting window 56 on the printer 100 main body side so as to be desired. When light is emitted from the light emitting portion of the light emitting / receiving element 58, it passes through the transparent window 56 and enters the first chamber 49a. If there is nothing to block, it is reflected by the reflecting mirror 57 and passes through the transparent window 56, It returns to the light receiving portion side of the light emitting / light receiving element 58 again.

Now, assuming that the toner is sufficiently present in the first chamber 49a and the conveying blade 55 is rotating at an appropriate speed, the toner is picked up by the conveying blade 55 toward the upper right side in the drawing. The conveying blade 55 wipes the inner surface of the light transmitting window 56 at the same time when it is picked up. Collapse. Since the fallen toner covers the transparent window 56, the light emitting / receiving element 58
Light will be blocked. In such a state, light does not pass through.

When the amount of toner in the first chamber 49a becomes low,
It takes time for the toner to collapse and cover the transparent window 56. Therefore, there appears a time in which the light emitted from the light emitting unit returns to the light receiving unit, and even in that case, only a partial area of the light transmitting window 56 is covered, and the amount of light returning increases.

When the amount of toner is further reduced, there is no toner to be collapsed so that the collapse does not occur, and the light is not shielded until the conveyor blade 55 rotates next after the conveyor blade 55 scrapes up the toner.

As described above, since the light transmission time and the returning light amount change depending on the remaining toner amount, the remaining toner amount (toner empty) is monitored by monitoring the signal output from the light receiving portion of the light emitting / light receiving element 58. Can be monitored.
FIG. 3 is an example of a waveform chart showing an output waveform generated by the light emitting / receiving element 58 according to the remaining amount of toner and a waveform formed by shaping the output waveform. The light emitting / light receiving element 58 has a characteristic that its output voltage decreases from level H to level L as the amount of received light increases, and the amount of received light is equal to or greater than a certain value (the output voltage is equal to L0.
When the trigger level (below) is reached, the timer 59 starts counting and the time t during which this trigger level continues is measured.

When the remaining amount of toner is sufficiently large, the light from the light emitting / receiving element 58 is not shielded as described above, so that its output voltage is maintained high. In this case, since the timer 59 does not start counting, the count time is t =
It is 0. When an appropriate amount of toner is consumed, the time for the light of the light emitting / receiving element 58 to pass through begins to appear, and as the toner consumption increases, the count value t of the timer 59 increases.
Grows larger.

The count threshold value t0 is a set value for comparison, which indicates that when the count value t exceeds the count threshold value t0, the remaining toner amount is less than the specified amount and it is no longer appropriate to print any more. Therefore, the timer 59
When the count value t of exceeds the count threshold t0, a warning is issued or the image forming apparatus is stopped.

However, since the toner collapse time is delayed by chance, any of a plurality of consecutive measurement results exceeds the count threshold value t0, or based on the frequency, the above warning or stop is performed. It is preferable to allow it. Further, regarding an example of the imaging unit 4,
FIG. 4 shows an example of a graph showing the relationship between the remaining amount of toner in the first chamber 49a and the timer count value t.

As described above, the fluidity of the powdery toner varies depending on the environment in which the image forming apparatus is placed, even under the same conditions, so that the time for the toner to collapse is also reduced. Change. Conventionally, this has not been recognized,
Further, since no countermeasure is taken, the count threshold value t0 is set constant regardless of the environment. Therefore, the remaining toner amount is not accurately detected, and the toner empty warning is issued or the image forming apparatus is stopped even if the remaining toner amount is still sufficient, or an image with a normal toner remaining amount is displayed. The image forming work was sometimes performed as it was, though it was not enough to form the image.

In this embodiment, humidity is selected as the environmental condition that most affects the toner fluidity, thereby improving the inaccuracy of toner empty detection as described above. First, in FIG. 5, the height h (FIG. 2) from the top of the replenishing roller 53 to the toner surface is measured in the longitudinal direction (the depth direction of the paper surface in FIG. 2) in order to see the influence of the humidity on the fluidity.
It is the graph which measured this about each position of, and plotted this. As can be seen from this graph, the lower the humidity is, the higher the height h is, so that the fluidity of the toner is lowered and the toner tends not to collapse.
Conversely, it can be said that the height h is increased as a result of the decrease in the fluidity of the toner. Further, since the height h also indicates the amount of toner in the second chamber 49b, when the height h is high, a large amount of toner remains in the entire imaging unit 4 as a whole. Become.

Therefore, it can be seen that when the humidity is low, the above-mentioned timer count value t becomes larger than when the humidity is low, even if the remaining amount of toner is actually the same. In other words, it can be seen that at low humidity, a toner empty signal may be output although the required toner remains.

As described above, since environmental conditions such as humidity cause an error in toner empty detection, the humidity sensor 43 is provided inside the printer 100 in this embodiment to detect environmental conditions. . The environment sensor such as the humidity sensor 43 may be provided in an appropriate place such as in the first chamber 49a, outside the printer 100, or in an appropriate place inside / outside the apparatus installation room apart from the printer 100.

The humidity sensor 43 measures the humidity therein periodically, for example, at a fixed time every day, and this data is accumulated in the control unit 88 (FIG. 1) for a certain period. Control unit 8
Reference numeral 8 determines the influence of an error due to humidity based on these data, and changes the parameter (count threshold t0) of the toner empty detection operation.

FIG. 6 is a flow chart showing the operation of the control unit 88. This subroutine starts (S
Then, first, it is determined whether it is the detection timing. This timing is whether or not to hit the first print of the day when the humidity is detected once a day. "N
In the case of “O”, the process proceeds to step S05, the count value t of the timer 59 is compared with the count threshold value t0 already determined at that time, and when the count value t is larger, the count value t is 2 times It may be determined) (S06).

If the result of this determination is "NO", the flow advances to step S99 to exit this subroutine. In the case of "YES", the process advances to step S06 to issue a toner empty warning (or the printer may be stopped).

The judgment in step S01 is "YE
If “S”, the process proceeds to step S02, where the humidity sensor 4
Take that output from 3. Then, the process proceeds to step S03, the old data is discarded, the newly fetched humidity data is stored, the sum of the humidity data for the past several days, for example, 10 days (sum of humidity) is obtained, and the process proceeds to the next step S04.

In step S04, a new count threshold value t0 is calculated based on the sum of the humidity values calculated in step S03 by referring to the correspondence table described below. The subsequent steps from step S05 are as already described.

FIG. 7 is a correspondence table showing the relationship of the new count threshold t0 to be set with respect to the sum of the humidity. The count threshold value t0 is related according to the category of the sum of humidity for several days (for 10 days). When the humidity is low, the fluidity of the toner decreases and the count value t
In order to increase the flow rate of the toner, the count threshold value t0, which is the basis for comparison, should be increased. On the contrary, if the humidity is high, the fluidity of the toner increases and the count value t increases.
The count threshold value t0 is made smaller in response to a smaller value. The humidity shown above is relative humidity, but it can be absolute humidity, and the above "sum" can be an average value.

In the printer disclosed above, humidity is selected as the environmental condition, but other environmental conditions that cause an error in toner empty detection can be selected. For example, since temperature also causes an error in toner empty detection, the temperature can be selected as an environmental condition instead of or in combination with humidity. In this case, a temperature sensor is provided instead of or in combination with the humidity sensor 43. Needless to say, the correspondence table also has different numerical values and items accordingly.

Further, the influence of the environmental conditions such as the humidity and the temperature and the influence of the period during which the toner is exposed to the environment appear intricately entangled with each other to change the fluidity, and moreover, depending on the structure of the printer. Needless to say, it is necessary to stack experiments to create a correspondence table because they are different.

Although the image forming apparatus described in this example is a monochrome printer, the technology disclosed herein is applied to any image forming apparatus that uses toner, such as a color printer, a monochrome copying machine, or a color copying machine. It is clear that you can. Further, although an example in which a scraping-up type toner remaining amount detection is performed is shown here, it is clear that the present invention can also be applied to a toner remaining amount detection device using sound waves, magnetism, etc. for remaining amount detection. is there.

Also, although the control unit 88 is shown as if it were a single one, this is merely as illustrated in the figure, so it may consist of multiple control units, Furthermore, it is also possible to allow a print server outside the image forming apparatus to perform some of the above functions.

Furthermore, the present invention is not limited to a single unit like the above-described imaging unit, and the present invention is applicable even if the first chamber and the second chamber are separated. be able to.

[0053]

According to the present invention, by detecting the environment to which the toner is exposed, the detection condition of the detecting means for detecting the remaining amount of toner in the image forming apparatus is changed according to this environment. Therefore, the image forming apparatus and further the toner empty detection apparatus have an effect that the influence of the environment is reduced or eliminated, and stable and accurate toner empty detection can be performed.

[Brief description of drawings]

FIG. 1 is a schematic view of a central cross section of an example printer 100.

FIG. 2 is an enlarged view showing the periphery of the photosensitive drum 1 in an enlarged manner.

FIG. 3 is an example of a waveform chart showing an output waveform generated by the light emitting / receiving element 58 according to the remaining amount of toner and a waveform formed by shaping the output waveform.

FIG. 4 is a graph showing the relationship between the remaining amount of toner in the first chamber 49a and the timer count value t.

FIG. 5 is a graph in which the height h from the top of the supply roller 53 to the toner surface is plotted at each position in the longitudinal direction.

6 is a flowchart showing the operation of the control unit 88. FIG.

FIG. 7 is a correspondence table showing the relationship between the count threshold t0 and the sum of humidity.

[Explanation of symbols]

1 photoconductor drum 2 Charging device 3 exposure equipment 4 Imaging unit 6 Transfer roller 7 cleaner 41 developing roller 43 Humidity sensor 49 development housing 51 First Regulation Blade 52 Second regulation blade 53 Supply roller 54 Static eliminator 55 Conveyor blade 56 translucent window 57 Reflector 58 Light emitting and receiving elements 59 timer 81, 82 cassettes 83 Bypass tray 84 Conveyor roller pair 85 Pair of fixing rollers 86 Guide 87 Ejection tray 88 control unit 100 printers 49a Room 1 49b Second room 49c passage hole

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hisashi Murata             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. (72) Inventor Hideaki Hayashi             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. (72) Inventor Kenichi Uemura             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. F-term (reference) 2H077 AB04 AB13 AE03 BA02 DA16                       DA18 DA34 DA64 DA78 DA81                       DB03 DB10 DB14 DB22

Claims (5)

[Claims] 1. A first detecting means for detecting a remaining amount of toner in an image forming apparatus, a second detecting means for detecting an environment to which the toner is exposed, and the first detecting means. Detecting means for changing the detecting condition, and controlling the detecting condition changing means so as to change the detecting condition of the first detecting means according to the detection result of the second detecting means. A toner empty detection device comprising: 2. The toner empty detection device according to claim 1, wherein the first detection means uses a toner collapse time as a detection condition. 3. The toner empty detecting device according to claim 1, wherein the environment to which the toner is detected by the second detecting means is in the image forming apparatus and / or. A toner empty detection device characterized in that the temperature and / or humidity is outside the image forming apparatus. 4. The toner empty detection device according to claim 1, wherein the detection result of the second detection means is an integrated value or an average value per predetermined time. A toner empty detection device characterized by the above. 5. A first detecting step for detecting the remaining amount of toner in the image forming apparatus, a second detecting step for detecting an environment to which the toner is exposed, and the first detecting step. 2. A toner empty detection method, comprising: a detection condition control step for changing the detection condition for the detection performed in 1. according to the detection result in the second detection step.