JPH11295977A - Toner supply method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner supply method for use in image forming device whereby toner is electrified in a short time by a simple structure and, in particular even in image formation in which the sizes of the outputs of transfer images are different, the toner can be electrified steadily at all times. SOLUTION: In the toner supply method in which toner concentration is measured by a detection means and toner is supplied into a developing device so that the value of the measurement falls within an effective area, thereby controlling the toner density, the effective area for the toner density in the developing device is divided into a plurality of areas (a)-(e), a toner supply cycle is set for each area, toner is supplied into the developing device by a fixed amount at the cycle corresponding to the area including the value of the measurement detected by the detection means during the operation of the developing device, and thus the toner density is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a method and a device for supplying toner to a developing device in an image forming apparatus such as a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine or a printer, a photosensitive member is uniformly charged by a corona charger, and image data is projected on the photosensitive member by an optical projection device to form a latent image. The latent image is developed by a developing device to form a toner image.

The developing device uses a two-component developer composed of a toner and a carrier. For example, the toner and the carrier are stirred by a screw or a stirring plate as stirring / circulating means provided in the developing device to charge the toner. Let me. The developer agitated by the agitating / circulating means is conveyed to a developing roller located at a position facing the photoreceptor and having a magnet disposed therein. The magnet and / or the developing roller are rotatably provided, and a magnetic brush is formed on the surface of the developing roller. The magnetic brush is brought close to or rubbed against the surface of the photoconductor, and only toner adheres to the photoconductor by the action of electrostatic attraction to form a toner image. Thereafter, the toner image on the photoconductor is transferred onto a transfer material, fixed as a permanent image by a fixing device, and discharged outside the image forming apparatus.

It is necessary to supply the toner consumed by the image formation into the developing device, and toner for replenishment is appropriately supplied into the developing device by a toner cartridge, a toner hopper, or the like. The supplied toner is stirred and circulated with the carrier stored in the developing device, and is prepared for the next image formation.

As an example of a system for supplying toner for replenishment into the developing device, a toner detecting means for measuring the toner concentration of the developer is provided in the developing device, and a toner concentration sensor as the toner detecting means is provided in the developing device. The toner concentration of
A supply signal is output when the toner concentration in the developing device falls below a value set in a preset effective area, and based on this signal, a supply means such as a supply screw provided in the toner cartridge is driven to supply toner. It is carried out.

The toner for replenishment is supplied to the developing device continuously during the period in which the supply signal is being output or by a fixed amount at a set cycle.

As an example of the toner density sensor, the ratio between the magnetic carrier and the non-magnetic toner is considered as a change in the magnetic susceptibility, and the analog output voltage changes in accordance with the change in the toner density. The toner density is detected using the change in the analog output voltage.

[0008]

On the other hand, the amount of toner consumed by image formation varies greatly depending on the printing rate on a transfer material. Further, the amount of toner consumption greatly differs between continuous copying and copying one sheet at a time. For example,
When forming copy images having a small printing rate one by one, the amount of toner consumption is small, and the amount of toner to be supplied into the developing device can be reduced accordingly. On the other hand, when continuously forming copy images with a high printing rate, the amount of toner consumption is orders of magnitude greater than when forming images one by one, and the amount of toner supplied into the developing device is also increased. .

Further, as the supply amount of the toner increases, the time required for mixing the developer stored in the developing device with the supplied toner increases, and accordingly, the time until the toner is sufficiently charged increases. Become.

In the above-described toner supply method, a time during which toner for supply is supplied and a time during which toner is not supplied are separated, and a large amount of toner is supplied into the developing device at a time when toner is supplied. It must be supplied, and the desired toner concentration cannot be obtained. In other words, if the toner consumption is small, the developer in the developing device and the supplied toner are mixed in a short time and sufficient charging for image formation is performed. The image formation is performed in a state where the charged toner is not sufficiently charged, which causes problems such as stains on the back of the transfer material and a decrease in image density during image formation. In order to improve this, it is sufficient to form an image after sufficiently stirring the toner, but it takes a long time until the image is output, so that high speed cannot be expected.

Particularly, in an image forming apparatus capable of selecting and outputting copy images of different sizes, such as A4 to A0, including a large-size transfer material, a difference in toner consumption is caused by a difference in transfer material size. It becomes remarkable depending on the type,
With the conventional supply method, it is impossible to maintain an appropriate developer concentration in the developing device, and it is not possible to achieve high-speed image formation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and a simple structure allows the toner to be charged in a short time. Particularly, even when forming images having different output sizes of transferred images, the present invention is always stable. It is an object of the present invention to provide a toner supply method for an image forming apparatus, which can charge a charged toner.

[0013]

In order to solve the above-mentioned problems, the present invention measures the toner concentration of a developer comprising a toner and a carrier stirred in a developing device by a detecting means, and sets the measured value. In a toner supply method for controlling the toner density by supplying toner to a developing device so as to have a value within the effective area, the effective area of the toner density in the developing apparatus is divided into a plurality of areas, and The toner supply cycle is set for each of the toner supply units, and the toner density is controlled by supplying the toner into the development device at a constant rate in a cycle corresponding to a region including the measurement value detected by the detection unit during operation of the development device. It is characterized by doing.

In the control of the toner density, when the toner density reaches a low density area outside the effective area, the image forming operation is interrupted until the toner density falls within the effective area. In the control of the toner density, when the toner density reaches a high density area outside the effective area, the toner supply is interrupted until the toner density reaches a predetermined area.

Further, in the image formation, transfer materials of different sizes are used, and the cycle is set for each size of the transfer material.

Further, detecting means for measuring the toner concentration of a developer comprising toner and carrier stirred in the developing device, supplying means for supplying replenishing toner into the developing device, and detecting by the detecting means Control means for controlling the toner density by supplying the toner for replenishment into the developing device by the supply means so that the measured value becomes a value within the set effective area of the toner density. Dividing the effective area into a plurality of areas,
And a storage unit for storing data of a toner supply cycle corresponding to the size of the transfer material used for each of these areas, and detecting the size of the transfer material used and the detection unit during operation of the developing device. The toner density is controlled by supplying the toner into the developing device in a fixed amount at a data cycle of the storage unit based on the measured value.

In such a configuration, the toner concentration is controlled by supplying a fixed amount of toner into the developing device at a period set in a region corresponding to the value of the toner concentration detected by the detecting means during the operation of the developing device. By this control, an amount of toner corresponding to the average printing rate of the transfer material is periodically supplied to the developing device, and the toner is charged in a short time.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of an image forming apparatus applied to the toner supply method and the apparatus of the present invention. An image forming apparatus 1 such as a copying machine or a printer is roughly divided into an image forming unit 2, a transfer material conveying guide unit 3,
The fixing device 4 includes a fixing device 4 and a roll paper feeding unit 9.

In the image forming section 2, a corona charger 6 for uniformly charging the surface of the photosensitive drum 5 around the photosensitive drum 5, and original data read by a scanner or the like are projected by an LED or the like and exposed to light. An optical projection device 7 for forming a latent image on the drum 5, a developing device 8 for developing the latent image, and a photosensitive drum 5 on a transfer material sent from a paper feeding unit 9 loaded with roll paper (or cut paper) Transfer corona discharger 1 for transferring the toner image formed thereon by the developing device 4
0, an AC separation corona discharger 11 for separating the transfer material from the photosensitive drum 5, a cleaning device 12 for removing the toner remaining on the surface of the photosensitive drum 5 after the transfer, and a uniform surface potential on the surface of the processing drum 5. And an eraser lamp 13 which is arranged so as to sequentially act on the photosensitive drum 5 to form an image in a known manner.

Reference numeral 20 denotes a toner cartridge filled with toner for replenishment. The toner cartridge 20 has a toner supply port 19 provided at one end in the longitudinal direction of the developing device 8 (on the side in the axial direction of the photosensitive drum 5). The toner in the cartridge 20 is supplied according to a supply signal. The supply port 21 of the toner cartridge 20 is covered with a guide member 22 so that toner does not scatter in the apparatus at the time of supply, and is connected by pressing around the port with a sponge 23 or the like. Sign 1
Reference numeral 5 denotes a waste bottle that stores the toner removed by the cleaning device 12.

FIG. 2 is a sectional side view of the developing device 8. In the figure, a casing 24 of the developing device 8 is
Has an opening 25 facing a part of the surface of the
A developing roller 26 is provided so as to expose a part of the peripheral surface of the photosensitive drum 5 and to approach the photosensitive drum 5. An agitating / circulating means 100 is provided for agitating and circulating the developer 29 stored in the developing device 8 and the supplied toner in the vicinity of the developing roller 26. The stirring / circulating means 100 has a first screw 36 rotating in the direction of arrow A and a second screw 37 rotating in the direction of arrow B as shown in the figure.
Reference numeral 32 denotes a partition plate, reference numeral 49 denotes a toner density sensor described later, and reference numeral 50 denotes a toner detection sensor as a detecting unit.

The developing roller 26 includes a sleeve 27 formed in a cylindrical shape and rotatable in the direction of arrow C, and a sleeve 2.
7 and a permanent magnet 28 fixedly arranged along the inner peripheral surface. The developer 29 is attracted to the surface of the sleeve 27 by the action of the rotation of the sleeve 27 and the magnetic force of the permanent magnet 28, and the magnetic brush 30 is formed. The magnetic brush 30
The regulating plate 31 regulates the electrostatic latent image formed on the photosensitive drum 5 by rubbing or non-contacting the peripheral surface of the photosensitive drum 5 to form a toner image. In the embodiment, the developing roller 26 in which the sleeve 27 rotates around the fixed permanent magnet 28 is illustrated. However, the developing roller 26 has a fixedly arranged sleeve and a permanent magnet rotatably provided in the sleeve. May be.

FIG. 3 shows the internal structure of the casing 24 of the developing device 8. The casing 24 has storage chambers 33 and 34 formed by dividing the center in the width direction by a partition plate 32, and a toner supply port 35 for supplying toner into the storage chamber 33 is provided at one end of the storage chamber 33. ing. Partition plate 32
Is a communication passage 32 that connects the storage room 33 and the storage room 34.
A, 32B, and the developer is conveyed by a first screw 36 and a second screw 37 disposed close to each other in the casing 24 to form a circulation path.

The agitating / circulating means 100 will be described. The first screw 36 and the second screw 37
Has stirring blades 36B and 37B, respectively, and is rotated by a motor 38 in the directions of arrows A and B as shown in FIG. By the action of the stirring blades 36B and 37B, the developer is transported in the directions of arrow D and arrow E, and is further supplied to the developer in the developing device 8 by passing the developer through the communication paths 32A and 32B. The toner and the toner are stirred and circulated.

Reference numeral 49 denotes a toner density sensor, which is provided on a side surface of the developing device 8 and detects a mixing ratio (density) between toner and carrier in the developing device. The toner density sensor 49 is configured by a magnetic sensor, and outputs the toner density of the developer in the storage chamber 33 as an output voltage based on a difference in magnetic permeability. For example, if the output voltage is 2.7 V, the toner concentration indicates 6 wt%, and 3.1.
If it is V, the toner density indicates 3%, and the relationship between the toner density and the output voltage changes almost linearly.

Reference numeral 50 denotes a toner detection sensor, which is provided below the toner supply port 35 and in which a fixed amount of toner is filled in a toner storage section 51 formed in a space around the third screw 41 in the storage chamber 33. The third screw 41 is driven for a predetermined period of time at predetermined intervals based on a supply signal to be described later to detect whether or not the toner amount in the storage unit 51 is equal to or greater than the amount of the toner. 1 screw 3
Supply to 6. For example, by rotating the third screw 41 for 0.2 seconds every predetermined period, about 0.1 g of toner is supplied to the first screw 36 each time. The toner detection sensor 50 detects that the toner has been exhausted in the toner storage unit 51 by this supply,
Based on this detection signal, the toner in the toner cartridge or the toner hopper is filled into the toner storage section 51. The supply of the toner by the third screw 41 was every 0.2 seconds in the embodiment, but is not limited to this value, and is preferably in the range of 0.1 seconds to 0.5 seconds.

The toner supply method of the present invention having such a configuration will be described with reference to FIGS. FIG. 4 is an example in which the change in the toner density in the developing device based on the signal detected by the detecting means is shown in a time series. The vertical axis shows the toner density, and the horizontal axis shows the passage of time. An effective area of the toner density in the developing device in which an image can be formed is set within an upper limit X and a lower limit Y, and the effective area is further divided into a plurality. In the embodiment, an example of dividing into five is shown.
The respective areas are indicated by a, b, c, d, and e.

FIG. 5 shows the toner supply cycle set for each of the areas a, b, c, d, and e. In the embodiment, the supply time of the toner is set to 0.1 per cycle.
The supply amount is set to about 0.1 g at a time of 2 seconds.
For each area, it is set so that when the toner density in the developing device is low, the toner is supplied in a short cycle, and when the toner density is high, the toner is supplied in a long cycle. The toner is supplied so as to match the printing rate of the transfer material. For example, by quantitatively supplying the same amount of toner as the amount of toner consumed during continuous copying at a certain printing rate, the amount of toner consumed and the amount of supplied toner substantially match, and a certain amount of toner is supplied. Stable image formation is performed while maintaining the toner density. Such a toner supply amount is predicted and set in advance for each area.

For example, in the case where the toner density is located in the area c, if the copy image has the first printing rate, the consumption amount of the toner and the supply amount of the toner substantially coincide with each other. Image formation can be performed. Next, when an image is formed at a second printing rate higher than the first printing rate, the amount of consumed toner is larger than the amount of supplied toner. For this reason, if the toner density is low, the detecting means detects the toner density, and the toner density is located in the area d, and the toner is supplied into the developing device at the toner supply cycle set in the area d. Since this period is set shorter than the period of the region c, the toner supply amount and the toner consumption amount substantially coincide again, and the toner concentration is stabilized in the region d. Further, when the toner consumption amount and the toner supply amount do not match, the detection unit detects that the region is another region, and thus the toner supply is performed at the toner supply cycle set in this region.

On the other hand, when an image is formed at a third printing rate lower than the first printing rate, the amount of consumed toner is smaller than the amount of supplied toner. Therefore, the detection means detects that the toner density is high, and the toner density is located in the area b, so that the toner is supplied into the developing device at the toner supply cycle set in the area b. Since this cycle is set longer than the cycle of the region c, the toner supply amount and the toner consumption amount substantially coincide again, and the toner density is stabilized in the region b.

When the size of the transfer material to be used is different, for example, A0, A1, A2, etc., the toner consumption is different even at the same printing rate. For this reason,
As shown in FIG. 6, a cycle corresponding to each area and each size is set in advance. For example, the third screw is driven at a cycle corresponding to FIG. 6 to supply toner by a signal from a detection unit for detecting the size of the transfer material and an output signal indicating an area where the toner density is located. doing.

FIG. 7 is a block diagram showing the control of the toner supply device. In the figure, a toner density sensor 49 for detecting the toner density in the developing device, a driving motor 62 for driving the third screw 41, a control means 60 including an arithmetic circuit 63 for controlling the driving motor 62, Storage means 61 for storing data of the toner supply cycle corresponding to the size of the transfer material to be used. The toner density sensor 49 detects the toner density in the developing device during the operation of the developing device 8, and outputs a detection signal to the control unit 60. The control means 60 calculates an area where the toner density is located from an analog voltage as a detection signal by an arithmetic circuit 63, and indicates a signal indicating this area and the size of the transfer material sent from a control panel or the like. The period of toner supply corresponding to the signal is taken from the storage means,
The drive motor 62 is driven based on this data.

Image formation is performed by the above-described control of the toner density, and when the toner density in the developing device increases and exceeds the upper limit X of the effective area, the supply of the toner is stopped and the image formation is performed as it is. Control. Further, when the toner density in the developing device becomes lower and falls below the lower limit Y of the effective area, the supply of toner is kept as it is, the image formation is stopped, and the image formation is restarted when the toner density reaches the effective area. I do.

Preferably, the supply of toner is controlled during the idle operation of the developing device after turning on the main power supply of the image forming device and during the initial few seconds of the operation of the developing device during image formation. Not to be. As a result, a rapid change in toner density is reduced, and stable control can be performed.

[0035]

As described above, unlike the method of continuously supplying the toner into the developing device, the small amount of the toner is supplied in each of a plurality of areas at a cycle set according to the type of the transfer material. Accordingly, stirring and mixing with the developer in the developing device can be easily performed, and the toner can be set to a charging potential at which image formation can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image forming apparatus applied to a toner supply method and an apparatus according to the present invention.

FIG. 2 is a side sectional view showing a developing device.

FIG. 3 is a plan view showing a screw portion of the developing device.

FIG. 4 is a conceptual diagram illustrating a change in toner density in the toner supply method according to the present invention.

FIG. 5 is a diagram illustrating a toner supply cycle in each area.

FIG. 6 is a diagram illustrating data of a toner supply cycle according to the size of a transfer material.

FIG. 7 is a block diagram illustrating a toner supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image forming part 3 Conveyance guiding part 4 Fixing device 5 Photosensitive drum 6 Corona charger 7 Optical projection device 8 Developing device 9 Roll paper feeder 10 Transfer corona discharger 11 AC separation corona charger 12 Cleaning device 13 Eraser lamp 15 Waste bottle 19 Toner supply port 20 Toner cartridge 21 Supply port 22 Guide member 23 Sponge 24 Casing 25 Opening 26 Developing roller 27 Sleeve 28 Permanent magnet 29 Developer 30 Magnetic brush 31 Regulator plate 32 Partition plate 32A, B communication passage 33 Storage chamber 34 Storage chamber 35 Toner supply port 36 First screw 36B Stirring blade 37 Second screw 37B Stirring blade 38 Motor 41 Third screw 49 Toner density sensor 50 Toner detection sensor 51 Toner storage unit 60 Control means 61 Storage means 62 Drive motor 63 Arithmetic circuit

Claims (5)

[Claims] The toner concentration of a developer comprising a toner and a carrier stirred in a developing device is measured by a detecting means, and the toner is injected into the developing device such that the measured value is within a set effective area. In the toner supply method of controlling the toner concentration by supplying the toner, the effective area of the toner concentration in the developing device is divided into a plurality of regions, and the supply period of the toner is set for each of these regions. A toner supply method, wherein a toner concentration is controlled by supplying a fixed amount of toner into the developing device at a period corresponding to a region including a measurement value detected by the detection unit during operation. 2. In the control of the toner density, when the toner density reaches a low density area outside the effective area, the image forming operation is interrupted until the toner density falls within the effective area. The method according to claim 1. 3. The toner density control according to claim 1, wherein when the toner density reaches a high density area outside the effective area, the toner supply is interrupted until the toner density reaches a predetermined area. 2. The toner supply method according to 1. 4. The toner supply method according to claim 1, wherein in the image formation, transfer materials of different sizes are used, and the cycle is set for each size of the transfer material. . 5. A detecting means for measuring a toner concentration of a developer comprising a toner and a carrier stirred in the developing device, a supplying means for supplying replenishing toner into the developing device, and a detecting means for detecting the toner concentration. Control means for controlling the toner density by supplying the toner for replenishment into the developing device by the supply means so that the measured value becomes a value within the set effective area of the toner density. Storage means for dividing the effective area into a plurality of areas and storing data of a toner supply cycle corresponding to the size of the transfer material used for each of the areas;
The toner density is controlled by supplying the toner into the developing device at regular intervals at a data cycle of the storage device based on the size of the transfer material to be used and the measurement value detected by the detecting device while the developing device is operating. A toner supply device characterized by the above-mentioned.