JPS5975270A - Developing device for electrophotographic device - Google Patents

Abstract

PURPOSE:To control toner density with high precision by supplementing toner powder to a developer according to the output signal of a detector which is buried in the developer carried while attracted to the outer circumferential surface of a sleeve and detects the height level of the developer scooped by a scooping member. CONSTITUTION:The oscillator of a piezoelectric element 32 is exposed on the top surface of the scooping member 30 and its amplitude is made small by the pressure of the developer 16 when the developer 16 building up along the member 30 contacts it and made large when not. The amplitude is detected by a detecting and an outputting circuit to energize and de-energize the clutch means of a toner supply roll 24. When the toner density of the developer 16 decreases below a specified value, the height level (h) of the developer 16 scooped on the sleeve 18 by the scooping member 30 decreases and the developer does not reaches the oscillator, and therefore the supply roll 24 is energized to scatter the supplement toner over the developer 16. When the toner density increases up to the specified value, the level of the developer 16 rises until the developer reaches the oscillator and the rotation of the supply roll 24 is stopped to complete the supplementation of the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION A casing for storing a developer made of a mixture of the following: a sleeve having a magnetic body disposed inside the sleeve that attracts the developer to an outer peripheral surface and conveys the developer; and a developer that adheres to the sleeve. The present invention relates to a developing device for an electronic copying device, including a regulating member that regulates the height of the spikes, and a toner concentration control device that controls the toner concentration of the developer.

One such device was published in Patent Application No. 1 and 6 in 1982.
]-261 Publication. This device scrapes the developer from its rotating sleeve and circulates it by changing the thickness of the developer flowing on a scraping plate that slopes downward from the tip that contacts the sleeve. It is detected at a position that is not close to the top, and therefore Ritona 3
- configured to detect changes of 1 S degree; ]7 However, this device has a problem in that it is relatively difficult to detect changes in toner concentration with high precision. An object of the present invention is to provide a developing device for an electrophotographic device.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1l is a rotating drum having a suitable photoreceptor 2 mounted on its circumferential surface, and is rotated in the direction indicated by arrow A during operation by being connected to a suitable driving means. During rotation, the photoreceptor 12 is subjected to the action of known static latent image forming means such as corona discharge and optical image irradiation to form an electrostatic latent image, that is, a potential difference image, in accordance with the original on its surface. This electrostatic latent image is then converted into a visible toner image by a developing device i13 and transferred to a suitable support.

The developing device 13 has a casing 15 having an opening 4 on the side facing the photoreceptor 12, and inside the casing, magnetic carrier powder such as iron powder (hereinafter simply referred to as carrier) and colored composite material are contained. A developer 16 made of a mixture of non-magnetic toner powder (hereinafter simply referred to as toner) such as resin is stored. The toner and carrier are sufficiently stirred by the rotation of the stirring portion 17, and are sufficiently adhered to each other by the frictional electricity generated at this time. A sleeve made of a non-magnetic material with a portion exposed through the opening 14 of the casing 15]. 8 is provided so as to be freely rotatable in N directions. A magnet assembly 20 having a plurality of magnet pieces 19 is fixedly arranged within the sleeve 18 and is independent of the daily rotation of the sleeve. The magnet pieces 19 are alternately arranged so that the S) and J polarities of the adjacent magnet pieces are reversed in the circumferential direction. The sleeve 18 is connected to a drive source (not shown) and rotates in the direction indicated by arrow B during operation. A portion of the developer stored in the casing 15 is attracted to the outer peripheral surface of the sleeve by the magnetic force of the magnet piece 19, and is transported in the direction of arrow B as the sleeve 18 rotates. During this conveyance, the developer that has slipped onto the sleeve 18 reaches a predetermined height (
It can be trimmed to the length of the hair. The developer then comes into contact with or comes close to the electrostatic latent image on the photoreceptor 12 and is electrostatically attracted onto the photoreceptor 12, forming a visible toner image corresponding to the electrostatic latent image. The developer that falls outside the illumination range exerted by the magnetic force of the last magnet piece 19a is removed from the IJ pipe 18 by the scraping plate 22, mixed into the stored developer and reused.

Reference numeral 23 in the figure is a toner storage container p1 casing 16
located above. Replenishment toner is stored inside the toner storage container 2JJ, and a supply row 224 connected to a suitable drive mechanism is provided below the toner storage container 2JJ. The supply roller 24 has an axial circumferential groove 25, and rotates as appropriate in response to a command from a toner concentration detection device, which will be described later, to replenish the developer with toner in the groove. The supply roller 24 is connected to a constantly rotating drive source via a clutch means such as an electromagnetic clutch or a spring clutch, and rotates or stops depending on whether the clutch means is energized or deenergized. Supply rotor 22
4 and its driving means, for example, the configuration described in the above-mentioned publication can be adopted.

The toner concentration detection device of the present invention has its lower end in a scoop portion 1'30 provided close to the sleeve. The scoop ferrule 30 is made of a non-magnetic material such as aluminum, brass, or synthetic resin, and its upper surface 30a is preferably formed to be smooth. The lower end of the rake part 30 is sleeve 1
The upper surface 1 of the scooping member 30, that is, the surface that scoops the developer, extends an appropriate length in the generatrix direction of the sleeve 18. lies substantially in a plane extending radially upward from the axis of the sleeve, or is inclined relative to said plane so as to open upwardly.

Further, the lower end of the scooping member 30 is disposed at a position where the developer in the vicinity receives substantially all of the magnetic force exerted by the magnet piece 19. A portion of the developer conveyed on the sleeve 18 due to the rotational force of the sleeve 18 and the magnetic force of the magnet piece 19 is scooped up by the scoop portion 30 . This scooped developer rises along the upper surface of the scooping member 30, and
The height level b, y of the raised portion is changed in accordance with the change in toner concentration in a positive relationship. That is, when the toner concentration is lower than the height for a developer having a desired toner concentration, the height level is completely lowered.

In order to detect changes in the height level of the developer, a suitable detection section [32 is provided, for example, on the scoop member 30. The detection portion of the detection device 32 is placed at a height such that it comes into contact with the raised developer when the developer has a desired toner concentration, but does not come into contact when the developer has a lower toner concentration. It is attached. As the detection device 32, a commercially available pressure
1 element (for example, TMS manufactured by Tokyo Denki Kagaku Kogyo Co., Ltd.)
type toner sensor) can be used. in this case,
As shown in FIG. 2, the sensing surface (vibrator) 32a of the piezoelectric element
It is preferable to slightly protrude from one surface of the scooping member 30 or to position it on the same plane. Furthermore, the detection device 32 may be a detection device that utilizes changes in the inductance of a coil element as described in the above-mentioned publication, or a known detection device consisting of a lamp and a photoelectric element as shown in Utility Model Application Publication No. 221.82 of 1982. It is also possible to adopt optical detection means, etc. In addition, the arrangement position I of the scoop member 30
Although it is preferable that W is provided approximately at the center of the sleeve in the longitudinal direction, it is not limited to this position.

Referring to FIG. 3, the developer detection operation when the piezoelectric sensor 32 is used as the detection device will be described. Pressure%, element 3
2 is an oscillation circuit 321) that oscillates an output at a predetermined frequency;
and a sensing section 32c that receives an output from the oscillation circuit 32b. The sensing section 32c has a vibrator 32ai that resonates with the output of the oscillation circuit 321). As described above, the vibrator 32a is exposed on the upper surface of the scoop member 30, and when the developer raised along the member 30 comes into contact with it, it reduces the amplitude due to the pressure of the developer, and when it does not come into contact with it, it reduces the amplitude. Let the amplitude be a dog. The magnitude of this amplitude is determined by the detection/output circuit 32cl.
Therefore, it is detected and output as either a H1gh level signal or a Low level signal.

This signal is sent to the clutch means of the toner supply roller 24 to energize or deenergize the clutch means.

When the toner concentration of the developer decreases below a predetermined value, the height level h of the developer scooped by the scooping member 30 on the sleeve 18 decreases, and the developer no longer reaches the vibrator 32a of the piezoelectric element 32. As a result, the detection/output circuit 32 (l) outputs a low-level signal indicating insufficient toner concentration, and the supply roller 24 is therefore energized to scatter replenishment toner onto the developer.The scattered toner is agitated. Due to the action of member 17, it is immediately mixed with the developer.

When the toner concentration reaches +Ji constant value due to toner replenishment, the level of the 011 developer on part 30 rises to the height where it contacts 14J and vibrator 32a, and as a result, the detection/output circuit 32d detects that the toner concentration is normal. A signal at the H1gh level shown in FIG. By repeating these operations, the developer in the developing device is always maintained within a predetermined toner concentration range.

In the experiment, the magnet piece 19 near the lower end of the scoop member 30
Using a magnet of 600 to 800G as the rake member 30
is inclined at an angle of 600 to 700 with respect to the tangent to the sleeve 18, and its lower end is separated from the sleeve at a certain distance (approximately 2 to 3 meters) to cover 1/3 of the thickness of the developer attached to the sleeve 8. When a piezoelectric element that responds to a pressure of 30 to 50 + nm f is used as a detection element and is placed opposite to the outer circumferential surface, the sensing part of the piezoelectric element is placed at a position where it can be contacted by, for example, a pile of developer with a toner concentration of 8 cm. In this case, the toner concentration in the developer could be controlled with an accuracy in the range of 8±0.5%.

FIG. 4 shows another embodiment of the developing device according to the present invention. In this example, the scoop 30 has a limited height H. That is, when trying to maintain the developer at a toner concentration of 8%, for example, if the developer has a toner concentration of 8% or more at the height H of the scooping member 30, the member 30? It is set so that it can rise and fall backwards. In this configuration, a detection means 40 is provided behind the member 30 in order to completely detect the presence (presence or absence) of developer falling from the member 30. As the detection means, a piezoelectric element, a coil body, an optical detection means, etc. as described above can be used. In the example shown in FIG. 4, the upper surface of the recessed part 1'41, where the sacro-slanted flat plate member 41 is placed at the position to receive the developer falling over the part 302, is smooth and smooth. Preferably, it is smooth so that it can flow. The center of the plate member 41 is cut out in a substantially circular hole shape, and a piezoelectric element 32 having the above-described configuration is formed.
The sensing surface (oscillator) of is exposed from there toward the upper surface of the member 41. The sensing surface protrudes slightly from the top surface of the plate member 41, or is preferably located flush with the top surface. In this configuration 7'c, when the developer has a predetermined toner concentration, that is, when the developer falls from the scoop member 30, the developer flows down the member 41-A, and the detector 32 detects that the developer is It is detected that the member 30 is falling. Such detection causes the output circuit 32d to indicate that the toner concentration is normal, as in the case described in the first embodiment. On the other hand, if the detection device 32 does not detect the developer falling, the toner supply roller is energized to replenish all the developer with toner until the detection device 32 detects the developer falling again. Incidentally, in order to reliably guide all of the developer falling from the member 30 onto the device 32, a guide member such as a funnel may be provided on the side 30 or between the member 30 and the sensing plate of the device 32. .

The timing of energizing the detection device 32 will be explained with reference to FIG. Generally, in an electrophotographic device, the developing device 1
operates only when developing. For this reason, the height level h of the developer particles scooped out by the transfer plate 30 is maintained for a certain period of time t from the start of the developing device (the start of rotation of the sleeve 18).
After 1, tar becomes stable. Therefore, the sensing device 32 is energized only during the period t2 after the elapse of time t1 until the end of one day of the sleeve.

As described above, the present invention provides a developing device that can control toner concentration with high accuracy.

In the above-described embodiments, a magnetic brush type developing device with a rotating sleeve and a fixed magnet has been described, but the present invention is also applicable to a developing device with a fixed sleeve and a rotating magnet or a rotating sleeve and magnet. applicable.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing one embodiment of the developing device according to the present invention, FIG. 2 is a perspective view of the device portion of No. 11, and FIG. 3 is a toner installed in the developing device according to the present invention. A block diagram for explaining the function of the density detection device; FIG. 4 is a schematic vertical cross-sectional view showing another embodiment of the developing device according to the present invention;
FIG. 5 is a timing chart showing the timing of activation of the toner concentration detection device incorporated in the developing device according to the present invention. 18a...Sleeve, 19...Magnet piece, 21...
- Regulation member, 30... scoop member, 32#... detection device. Patent applicant Figure 1

Claims (4)

[Claims] (1) A casing that stores a developer made of a mixture of magnetic carrier powder and non-magnetic toner powder, and a sleeve that has a magnet arranged inside and that attracts and transports the developer to its outer peripheral surface; In the developing device for an electrophotographic apparatus, the developing device includes a regulating member that regulates the height of the developer adhering to the sleeve, and a toner concentration control device that controls the toner concentration of the developer, wherein the toner concentration front control device , a lower end is buried in the developer on the sleeve at a position downstream of the regulating member when viewed in the developer transport direction and at a position where the magnetic force of the magnet body is applied to the developer on the sleeve, and the developer is transported. a scooping member disposed upright or inclined with respect to the direction; a detection device for detecting the height level of the developer scooped by the scooping member; 1. A developing device for an electrophotographic apparatus, comprising means for completely replenishing the body. (2) In the device according to item (1), the ω-detecting device is located at a predetermined distance from the outer peripheral surface of the sleeve.
is placed on the scoop 1 member, and the scoop is placed on the scoop 1 member.
The height level of the developer depends on whether the developer contacts or not.
A developing device 11 for an electrophotographic apparatus, characterized in that f4''A is known. (3) In the apparatus described in paragraph (2) above, the (・t
I! The sensing device is composed of a piezoelectric element that emits a predetermined output signal in response to the pressure caused by the scooped developer, and the pressure path of the element is flush with the surface in contact with the scooped developer on the scooping side. A developing device for an electrophotographic device, characterized in that the developing device is located above. (4) a casing that stores a developer made of a mixture of magnetic carrier powder and non-magnetic toner powder, and a sleeve that has a magnetic body arranged inside and that attracts and conveys the developer to its outer peripheral surface; In the developing device for an electrophotographic apparatus, the toner concentration control device includes a regulating member that regulates the height of the developer adhering to the sleeve, and a toner concentration control device that controls the toner concentration of the developer. The lower end is buried in the developer on the sleeve at a position downstream of the regulating member when viewed in the conveyance direction of the sleeve and at a position where the magnetic force of the magnet body is applied to the developer on the sleeve. a rake portion having a predetermined height that slopes downward;
An electrophotographic apparatus comprising: a detection device for detecting the presence of developer falling over the scoop portion (A1); and means for replenishing the developer with toner powder in response to an output signal of the detection device. development equipment.