JPH0472230B2 - - Google Patents
Info
- Publication number
- JPH0472230B2 JPH0472230B2 JP23059583A JP23059583A JPH0472230B2 JP H0472230 B2 JPH0472230 B2 JP H0472230B2 JP 23059583 A JP23059583 A JP 23059583A JP 23059583 A JP23059583 A JP 23059583A JP H0472230 B2 JPH0472230 B2 JP H0472230B2
- Authority
- JP
- Japan
- Prior art keywords
- developing
- magnetic
- bias potential
- flux density
- magnetic flux
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000005513 bias potential Methods 0.000 claims description 19
- 230000004907 flux Effects 0.000 claims description 17
- 238000001514 detection method Methods 0.000 claims description 8
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
- G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
- G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
- G03G15/0907—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush with bias voltage
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Magnetic Brush Developing In Electrophotography (AREA)
- Developing For Electrophotography (AREA)
Description
【発明の詳細な説明】
（技術分野）
本発明は、プリンターや複写装置として使用さ
れる電子写真装置の現像装置に関する。DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a developing device for an electrophotographic device used as a printer or a copying device.
（技術的背景）
感光ドラム等の静電潜像担持体を磁性トナーあ
るいは二成分現像剤によつて現像する方法として
磁気ブラシ現像方法が知られている。磁気ブラシ
現像方法では感光ドラムと相対して設置される現
像ロール内にマグネツトロールを有することによ
り、磁性トナーや二成分現像剤を現像ロールに磁
気保持力で吸引しており、静電潜像担持体と現像
ロール間で発生する静電吸引力がこの磁気保持力
に勝つたときには現像付着が発生する。(Technical Background) A magnetic brush development method is known as a method for developing an electrostatic latent image bearing member such as a photosensitive drum using a magnetic toner or a two-component developer. In the magnetic brush development method, by having a magnet roll in the developing roll installed opposite to the photosensitive drum, magnetic toner or two-component developer is attracted to the developing roll by magnetic holding force, and the electrostatic latent image is When the electrostatic attraction force generated between the carrier and the developing roll overcomes this magnetic holding force, development adhesion occurs.
しかしながら、磁性トナーや二成分現像剤を現
像領域に搬送する都合上からマグネツトロールを
回転する場合は磁気吸引力が時間的に変動する。
この磁気吸引力の時間的変動が感光ドラムの周速
に対して相対的に遅い場合は現像濃度にシマ模様
の濃度ムラが発生する欠点があつた。この濃度ム
ラの発生を防ぐためには、マグネツトロールは通
常1000rpm以上の高速回転を行う必要があるが、
このとき磁性トナーの飛散量が多くなり現像装置
周辺を汚す欠点があつた。 However, when the magnet roll is rotated to convey magnetic toner or two-component developer to the development area, the magnetic attraction force changes over time.
When the temporal variation of this magnetic attraction force is relatively slow with respect to the circumferential speed of the photosensitive drum, there is a drawback that density unevenness in a striped pattern occurs in the developed density. In order to prevent this density unevenness from occurring, the magnet roll usually needs to be rotated at a high speed of 1000 rpm or more.
At this time, there was a drawback that the amount of magnetic toner scattered increased and the area around the developing device was contaminated.
（発明の目的）
この発明の目的は、これらの欠点を除去し、マ
グネツトロールを低速に回転しても濃度ムラのな
い安定な現像を行うことができる電子写真現像装
置を提供することにある。(Object of the Invention) An object of the present invention is to provide an electrophotographic developing device that eliminates these drawbacks and can perform stable development without density unevenness even when the magnet roll is rotated at low speed. .
（発明の概要）
この発明は磁束密度検出手段によつてマグネツ
トロールの現像領域に対応する位置での磁束密度
を検出して、この検出信号で現像スリーブに印加
される現像バイアス電位を可変制御することを特
徴とするもので、以下実施例に基づき詳細に説明
する。(Summary of the Invention) This invention detects the magnetic flux density at a position corresponding to the developing area of the magnet roll using a magnetic flux density detection means, and uses this detection signal to variably control the developing bias potential applied to the developing sleeve. This feature is described in detail below based on examples.
（実施例）
第１図は、この発明の実施例を示す説明図であ
る。感光ドラム１は静電潜像担持体であつて図示
されていない潜像形成手段によつて表面に静電潜
像が形成されている。現像スリーブ２は非磁性金
属の円筒であり、マグネツトロール３は現像スリ
ーブ２の内側にあつて回動する。マグネツトロー
ル３は複数の磁極が円周方向に着磁されており、
通常Ｓ極とＮ極が交互に配置されている。トナー
ホツパー４は磁性トナー５、あるいは二成分系現
像剤（トナーとキヤリアの混合）を貯蔵してお
り、現像スリーブ２とマグネツトロール３の回転
によつて現像領域９、つまり感光ドラム１と現像
スリーブ２が微少間隔を保持して相対する領域に
磁性トナー５を搬送する。現像領域９における磁
束密度を検出するために、磁束密度検出手段とし
て例えばホール素子６が現像領域９と同一の磁束
分布を有する現像領域以外の現像スリーブ２の表
面と対向する位置に設けられる。(Example) FIG. 1 is an explanatory diagram showing an example of the present invention. The photosensitive drum 1 is an electrostatic latent image carrier and has an electrostatic latent image formed on its surface by a latent image forming means (not shown). The developing sleeve 2 is a cylinder made of non-magnetic metal, and the magnet roll 3 is located inside the developing sleeve 2 and rotates. The magnet roll 3 has multiple magnetic poles magnetized in the circumferential direction,
Usually, south poles and north poles are arranged alternately. The toner hopper 4 stores magnetic toner 5 or a two-component developer (a mixture of toner and carrier), and the rotation of the developing sleeve 2 and magnet roll 3 causes the developing area 9, that is, the photosensitive drum 1 and the developing sleeve 2 conveys the magnetic toner 5 to opposing areas while keeping a small distance therebetween. In order to detect the magnetic flux density in the developing region 9, a Hall element 6, for example, is provided as a magnetic flux density detecting means at a position facing the surface of the developing sleeve 2 other than the developing region having the same magnetic flux distribution as the developing region 9.
例えば、第１図では現像領域９と反対側の現像
スリーブ２の表面に対向する位置にホール素子６
が設けられる。通常、マグネツトロール３は偶数
の極を持ち、その磁極の強さを一定に着磁される
から、この設定位置でのホール素子６の検出信号
は現像領域の磁束密度と実用的には一致する。増
幅回路７は検出信号を増幅して現像バイアス電位
可変手段８に伝達する。現像バイアス電位可変手
段８の出力は現像スリーブ２と接続されており、
現像領域９で感光ドラム１の静電潜像電位と対応
する現像バイアス電位を与える。 For example, in FIG. 1, a Hall element 6 is located at a position facing the surface of the developing sleeve 2 on the opposite side to the developing area 9.
will be provided. Normally, the magnet roll 3 has an even number of poles and is magnetized with a constant magnetic pole strength, so the detection signal of the Hall element 6 at this setting position practically matches the magnetic flux density in the developing area. do. The amplifier circuit 7 amplifies the detection signal and transmits it to the developing bias potential variable means 8. The output of the developing bias potential variable means 8 is connected to the developing sleeve 2,
A developing bias potential corresponding to the electrostatic latent image potential of the photosensitive drum 1 is applied in the developing area 9 .
第２図はこの発明の現像領域の磁束密度と現像
バイアス電位の関係を示す波形図であつて、第２
図ａは現像領域の磁束密度を示す。横軸は時間
軸、縦軸は磁束密度であつて、Ｎ極とＳ極が交互
に通過する模様を示す。 FIG. 2 is a waveform diagram showing the relationship between the magnetic flux density of the developing area and the developing bias potential according to the present invention.
Figure a shows the magnetic flux density in the development area. The horizontal axis is the time axis, and the vertical axis is the magnetic flux density, which shows a pattern in which north and south poles pass alternately.
第２図ｂは正規現像における現像バイアス電位
VBの波形を示したもので、ホール素子６の出力
を全波整流的に整形した後に極性を反転した高電
位波形である。また、この現像バイアス電位VB
の最大値が潜像電位VSより小となるように設定
される。正規現像では感光ドラム１の潜像電位
VSと現像バイアス電位VBとの電位差（VS−VB）
が大きい程負帯電している磁性トナー５への静電
吸引力が強く作用する。つまり、第２図ａで示さ
れる如くＮ極とＳ極の極近傍では磁束密度が高く
磁気保持力が強いので現像バイアス電位をほぼ零
にして静電吸引力を強く作用させ、逆に磁極の境
界部分では磁束密度が低く磁気保持力が弱いので
現像バイアス電位を潜像電位VSに近づけて静電
吸引力を弱く作用させる。つまり、磁気保持力の
強弱に対応して静電吸引力を制御することができ
現像付着する磁性トナー５の量を時間的にほぼ均
一にすることができる。 Figure 2b shows the development bias potential in regular development.
This shows the waveform of VB , which is a high potential waveform obtained by reversing the polarity after the output of the Hall element 6 has been shaped in a full-wave rectification manner. Also, this developing bias potential V B
is set so that the maximum value of is smaller than the latent image potential V S . In regular development, the latent image potential of photosensitive drum 1
Potential difference between V S and developing bias potential V B (V S − V B )
The larger the value, the stronger the electrostatic attraction force exerted on the negatively charged magnetic toner 5. In other words, as shown in Figure 2a, near the N and S poles, the magnetic flux density is high and the magnetic coercive force is strong. At the boundary, the magnetic flux density is low and the magnetic coercive force is weak, so the developing bias potential is brought close to the latent image potential V S to weakly apply the electrostatic attractive force. In other words, the electrostatic attraction force can be controlled in accordance with the strength of the magnetic coercive force, and the amount of magnetic toner 5 that develops and adheres can be made almost uniform over time.
第２図ｃは反転現像における現像バイアス電位
VBの波形を示したもので、ホール素子６の出力
を全波整流的に整形した高電位波形であり、第２
図ｃに示す波形とは極性が反転している。また、
この現像バイアス電位VBの最小値は潜像電位VS
より大となるように設定される。反転現像では現
像バイアス電位VBと潜像電位VSとの電位差（VB
−VS）が大きい程正帯電している磁性トナー５
の静電吸引力が強く作用する。通常、感光ドラム
１の潜像電位VSが零に近い潜像部分に磁性トナ
ー５は付着する。つまりｃで示される現像バイア
ス電位VBの波形にすることにより、正規現像と
同様に磁気保持力の強弱に対応して静電吸引力を
制御させることができ、現像付着する磁性トナー
５の量を時間的にほぼ均一にすることができる。 Figure 2c shows the development bias potential in reversal development.
This shows the waveform of V B , which is a high potential waveform obtained by shaping the output of the Hall element 6 in a full-wave rectification manner.
The polarity is reversed from the waveform shown in Figure c. Also,
The minimum value of this developing bias potential V B is the latent image potential V S
is set to be larger. In reversal development, the potential difference between the development bias potential V B and the latent image potential V S (V B
−V S ) is larger, the more positively charged the magnetic toner 5 is.
The electrostatic attraction force acts strongly. Normally, the magnetic toner 5 adheres to the latent image portion of the photosensitive drum 1 where the latent image potential V S is close to zero. In other words, by setting the waveform of the developing bias potential V B as shown by c, it is possible to control the electrostatic attraction force in accordance with the strength of the magnetic coercive force in the same way as in regular development, and the amount of magnetic toner 5 that adheres during development. can be made almost uniform over time.
尚、第２図ａ，ｂ，ｃの各波形において、各時
間軸は一致するものである。 Note that the time axes of the waveforms in FIGS. 2a, b, and c are the same.
（発明の効果）
この発明は以上説明したように、磁束密度検出
手段（例えばホール素子）によつてマグネツトロ
ールの現像領域での磁束密度の検出を行い、その
検出信号で現像バイアスを制御する手段を設けた
のでマグネツトロールが感光ドラムの回転に対し
て比較的遅く回転しても現像濃度のシマ模様、す
なわち濃度ムラは現われない。(Effects of the Invention) As described above, the present invention detects the magnetic flux density in the developing area of the magnet roll using a magnetic flux density detection means (for example, a Hall element), and controls the developing bias using the detected signal. Since the means is provided, even if the magnet roll rotates relatively slowly with respect to the rotation of the photosensitive drum, a striped pattern in the developed density, that is, density unevenness does not appear.
さらに、磁気保持力の弱いときに静電吸引力を
弱くしているので過剰な磁性トナーの付着を防ぎ
画品質を向上することができる。また、マグネツ
トロールの回転数を低く抑えて現像するから磁性
トナーの飛散を抑えることができるため、現像装
置周辺を汚すことなく長時間安定した現像が行な
える。 Furthermore, since the electrostatic attraction force is weakened when the magnetic holding force is weak, it is possible to prevent excessive adhesion of magnetic toner and improve image quality. Furthermore, since development is carried out with the rotational speed of the magnet roll kept low, scattering of magnetic toner can be suppressed, so that stable development can be carried out for a long period of time without contaminating the area around the developing device.
以上の効果をもつので、この発明は高品質で安
定なプリンターや複写装置の電子写真現像装置に
利用することができる。 Because of the above effects, the present invention can be used in high-quality and stable electrophotographic developing devices for printers and copying machines.
第１図はこの発明の一実施例の説明図、第２図
はこの発明の現像領域の磁束密度と現像バイアス
電位との関係を示す波形図である。
１……感光ドラム、２……現像スリーブ、３…
…マグネツトロール、６……ホール素子、８……
現像バイアス電位可変手段。
FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram showing the relationship between the magnetic flux density of the developing region and the developing bias potential of the present invention. 1...Photosensitive drum, 2...Developing sleeve, 3...
...Magnet roll, 6...Hall element, 8...
Development bias potential variable means.
Claims (1)
内にあつて回動するマグネツトロールと、当該マ
グネツトロールの現象領域に対応する位置の磁束
密度を測定する磁束密度検出手段と、当該磁束密
度検出手段の検出出力に応じ現像バイアス電位を
可変するための現像バイアス電位可変手段とを有
し、前記現像バイアス電位可変手段より出力され
る現像バイアス電位が前記現像スリーブに印加さ
れることを特徴とする電子写真現像装置。1. A conductive developing sleeve, a magnet roll rotating within the developing sleeve, a magnetic flux density detection means for measuring magnetic flux density at a position corresponding to the phenomenon area of the magnet roll, and a magnetic flux density detection means. and a developing bias potential variable means for varying the developing bias potential according to the detection output of the means, and the developing bias potential outputted from the developing bias potential varying means is applied to the developing sleeve. Electrophotographic development equipment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23059583A JPS60122971A (en) | 1983-12-08 | 1983-12-08 | Electrophotographic developing device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23059583A JPS60122971A (en) | 1983-12-08 | 1983-12-08 | Electrophotographic developing device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60122971A JPS60122971A (en) | 1985-07-01 |
| JPH0472230B2 true JPH0472230B2 (en) | 1992-11-17 |
Family
ID=16910200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23059583A Granted JPS60122971A (en) | 1983-12-08 | 1983-12-08 | Electrophotographic developing device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60122971A (en) |
-
1983
- 1983-12-08 JP JP23059583A patent/JPS60122971A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60122971A (en) | 1985-07-01 |
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