JPS6226026B2 - - Google Patents
Info
- Publication number
- JPS6226026B2 JPS6226026B2 JP54136912A JP13691279A JPS6226026B2 JP S6226026 B2 JPS6226026 B2 JP S6226026B2 JP 54136912 A JP54136912 A JP 54136912A JP 13691279 A JP13691279 A JP 13691279A JP S6226026 B2 JPS6226026 B2 JP S6226026B2
- Authority
- JP
- Japan
- Prior art keywords
- toner
- transfer
- area
- photosensitive drum
- control grid
- 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
- 108091008695 photoreceptors Proteins 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 8
- 230000005684 electric field Effects 0.000 description 9
- 238000000034 method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 230000001737 promoting effect Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 229910018219 SeTe Inorganic materials 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- FESBVLZDDCQLFY-UHFFFAOYSA-N sete Chemical compound [Te]=[Se] FESBVLZDDCQLFY-UHFFFAOYSA-N 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
Landscapes
- Control Or Security For Electrophotography (AREA)
Description
【発明の詳細な説明】
本発明は電子写真感光体の画像部分のトナー転
写性を向上させる転写前コロナ放電器を有する電
子写真装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic apparatus having a pre-transfer corona discharger that improves toner transferability of an image portion of an electrophotographic photoreceptor.
従来第１図に概略図として示したカールソンプ
ロセスと呼ばれる電子写真法を適用した装置が知
られている。第１図の１は感光ドラム、２は感光
ドラムを一様に帯電するコロナ帯電器、３は原稿
台ガラス４上に置かれた原稿５の露光ランプ６に
よる反射光を感光ドラムに結像させる光学系、７
は現像器、８は顕画像を転写材９に転写する転写
帯電器、１０はクリーニング手段を示している。 2. Description of the Related Art Conventionally, an apparatus to which an electrophotographic method called the Carlson process, which is schematically shown in FIG. 1, is applied is known. In FIG. 1, 1 is a photosensitive drum, 2 is a corona charger that charges the photosensitive drum uniformly, and 3 is a corona charger that forms an image on the photosensitive drum of the light reflected by the exposure lamp 6 of the document 5 placed on the document table glass 4. optical system, 7
Reference numeral 8 indicates a developing device, 8 a transfer charger for transferring a developed image onto a transfer material 9, and 10 a cleaning means.
このような構成の電子写真装置は、Se，SeTe
等の無定形セレンを蒸着したAlシリンダーから
成る感光ドラム上に、正極性の一様帯電を行つて
感光ドラムを活性化し、次に原稿画像の明暗のパ
ターンを露光して感光ドラム上に明暗の静電潜像
パターンを形成するものである。通常感光ドラム
表面には明部潜像としてＶL＝＋200V、暗部潜像
としてＶD＝＋800Vの表面電位が得られる。次に
感光ドラムは現像行程に移り、粒径３〜15μの負
極性の熱可塑性樹脂粉体から成るトナーと、磁性
体キヤリアとの混合物からなる現像剤で可視化さ
れる。現像後の感光ドラム表面電位は、明部はほ
とんど変化せずＶL＝＋200Vを示しているが、明
部ではトナーの負極性電荷の影響を受けてＶD＝
＋700Vに若干低下している。現像により感光ド
ラム上の潜像に静電吸着したトナーは、その後転
写材の背面からトナー極性と逆極性の転写コロナ
放電を施すことによつて転写材上に転移させられ
る。 An electrophotographic device with such a configuration uses Se, SeTe
The photosensitive drum, which is made of an Al cylinder on which amorphous selenium such as It forms an electrostatic latent image pattern. Normally, a surface potential of V L =+200V as a bright latent image and V D =+800V as a dark latent image is obtained on the surface of the photosensitive drum. Next, the photosensitive drum is subjected to a developing process, and is visualized with a developer consisting of a mixture of a toner consisting of a thermoplastic resin powder of negative polarity with a particle size of 3 to 15 microns, and a magnetic carrier. The surface potential of the photosensitive drum after development shows almost no change in bright areas, showing V L = +200V, but in bright areas, V D = +200 V due to the influence of the negative polarity charge of the toner.
The voltage has dropped slightly to +700V. The toner electrostatically attracted to the latent image on the photosensitive drum during development is then transferred onto the transfer material by applying a transfer corona discharge of opposite polarity to the toner from the back side of the transfer material.
ところで従来よりコピー画像の品質が現像剤の
使用回数に依存することが知られている。例えば
新しい現像剤を使用した時には画像濃度も約1.4
と高く、白地のカブリも少ないが、30000〜50000
枚のコピーをとり終えた後の現像剤では画像濃度
は1.0に低下し、白地にカブリの目立つ画像とな
る。これは現像剤の変質、即ち現像剤劣化と呼ば
れている現象に起因する。 By the way, it has been known that the quality of a copy image depends on the number of times a developer is used. For example, when using a new developer, the image density is approximately 1.4.
30,000 to 50,000, although there is little fogging on white backgrounds.
After making a copy, the image density in the developer drops to 1.0, resulting in an image with noticeable fog on a white background. This is caused by a phenomenon called developer deterioration, that is, deterioration of the developer.
通常、使い込んだ現像剤中のトナー平均粒径は
当初よりも微傾向となつてくる。この理由は現像
時には７〜15μのトナーが選択的に付着しやす
く、使い込むと現像剤中に３〜５μのトナー微粉
の割合が増えてくるからである。このように微傾
向となつた現像剤では電気抵抗が上昇し、現像剤
それ自身による電極効果が減少するため、感光ド
ラム明部に付着するトナーが減少する。 Normally, the average particle size of toner in a used developer tends to be smaller than it was at the beginning. The reason for this is that during development, toner particles of 7 to 15 .mu.m tend to adhere selectively, and as the developer is used, the proportion of fine toner particles of 3 to 5 .mu.m increases in the developer. In the developer with such a slight tendency, the electric resistance increases and the electrode effect of the developer itself decreases, so that the amount of toner adhering to the bright area of the photosensitive drum decreases.
又、使い込んだ現像剤では転写性も低下してく
る。その理由の一つは、現像剤中のキヤリアの表
面を微粉トナーがおおつて他のトナーとキヤリア
との接触性が悪くなり、トナーの摩擦帯電電荷量
にムラを生じて、これが転写ムラにつながるから
である。 Further, if the developer is used, the transferability will also deteriorate. One of the reasons for this is that the surface of the carrier in the developer is covered with fine powder toner, which impairs the contact between the carrier and other toners, causing unevenness in the amount of triboelectric charge on the toner, which leads to uneven transfer. It is from.
更に又、使い込んだ現像剤ではトナーの転写率
も低下する。新しい現像剤を使用した場合には感
光ドラム上のトナーの80〜90％が転写材に転写さ
れるが、使い込んだ現像剤の転写率は60〜70％程
度に低下する。この理由は前記トナー電荷量のム
ラによることと、現像されたトナーがより微傾向
となつて感光ドラムとトナーの分子間力が増加す
ることによる。 Furthermore, the toner transfer rate decreases with the used developer. When new developer is used, 80 to 90% of the toner on the photosensitive drum is transferred to the transfer material, but the transfer rate of used developer drops to about 60 to 70%. The reason for this is that the toner charge amount is uneven, and that the developed toner has a finer tendency and the intermolecular force between the photosensitive drum and the toner increases.
従来現像器と転写帯電器との間に転写前帯電器
を設けて感光ドラム上のトナーにトナーと同極
性、又は逆極性のコロナチヤージを与え、トナー
の電荷量を転写に要するに十分な値にして転写性
の向上を計る方法が知られている。この転写前帯
電器を使用すると転写率も90〜95％程に改善さ
れ、ムラのない画像を得ることができる。この結
果使い込んだ現像剤を使用しても濃度が1.2〜1.3
の高濃度の画像を得ることができる。 Conventionally, a pre-transfer charger is provided between the developing device and the transfer charger, and a corona charge of the same polarity or the opposite polarity as the toner is applied to the toner on the photosensitive drum, and the charge amount of the toner is set to a value sufficient for transfer. Methods for improving transferability are known. Using this pre-transfer charger improves the transfer rate to about 90 to 95%, making it possible to obtain even images. As a result, even if used developer is used, the density is 1.2 to 1.3.
It is possible to obtain high-density images.
しかしながら、転写前帯電器を使用すると白地
部分のカブリも増えてくる。それは、感光ドラム
の明部に付着するトナーは一般的には、機械的接
触により付着する正極性トナー、又は非帯電トナ
ーであり、転写前帯電器がない場合、転写コロナ
極性が正である時にはほとんど転写材には転写さ
れないが、上述の転写前帯電器でコロナ放電を与
えると、感光ドラム上のカブリトナーも均一で十
分な量の電荷を持つようになり、容易に転写材に
転写されてしまうからである。その結果、従来の
装置ではカブリのある品質の低い画像になつてし
まう欠点がある。 However, when a pre-transfer charger is used, fogging on white background portions also increases. The toner that adheres to the bright area of the photosensitive drum is generally positive polarity toner that adheres by mechanical contact or uncharged toner, and if there is no pre-transfer charger and the transfer corona polarity is positive, Although it is hardly transferred to the transfer material, by applying corona discharge with the pre-transfer charger described above, the fog toner on the photosensitive drum becomes uniform and has a sufficient amount of charge, so that it is easily transferred to the transfer material. This is because it will be put away. As a result, conventional devices have the drawback of producing images with fog and poor quality.
本発明は上記従来の欠点を解決し、感光体上の
カブリトナーの転写を抑制しつつ画像部トナーの
転写性向上を計り、高品質の画像を得ることを可
能とした電子写真装置の提供を目的とするもので
ある。 The present invention solves the above-mentioned conventional drawbacks, and provides an electrophotographic apparatus that can suppress the transfer of fog toner on a photoreceptor while improving the transferability of toner in an image area, thereby making it possible to obtain high-quality images. This is the purpose.
本発明は電子写真装置の現像領域から転写領域
に至るまでの領域に制御格子を有する転写前コロ
ナ放電器を設け、この放電器のコロナ放電極にト
ナー極性と同極性の高圧電圧を印加し、制御格子
に現像後の感光体の暗部部分の電位ＶDと現像後
の感光体の明部部分の電位ＶLとの間にあるバイ
アス電圧を印加するものである。この構成によつ
て、感光体の暗部と制御格子の間にコロナ放電の
促進電界を形成し、暗部トナーをより強く帯電さ
せて転写率の向上を計り、逆に感光体の明部と制
御格子の間にはコロナ放電の抑制電界を形成して
カブリトナーが帯電されることを防止するもので
ある。 The present invention provides a pre-transfer corona discharger having a control grid in the area from the development area to the transfer area of an electrophotographic apparatus, applies a high voltage having the same polarity as the toner polarity to the corona discharge electrode of this discharger, A bias voltage between the potential V D of the dark portion of the photoreceptor after development and the potential V L of the bright portion of the photoreceptor after development is applied to the control grid. With this configuration, an electric field promoting corona discharge is formed between the dark area of the photoconductor and the control grid, and the dark area toner is charged more strongly to improve the transfer rate, and conversely, the toner in the dark area is charged more strongly to improve the transfer rate. An electric field for suppressing corona discharge is formed between the two to prevent the fog toner from being charged.
以下図面に基づいて本発明の実施例を説明す
る。 Embodiments of the present invention will be described below based on the drawings.
第２図は本発明の実施例を示す構成説明図であ
る。図中第１図と同一のものには同じ参照符号を
付してある。即ち１は感光ドラムであり、８は転
写帯電器、９は転写材である。感光ドラム１の表
面には暗部表面電位ＶD＋800V、明部表面電位Ｖ
L＋200Vの潜像が形成されている。現像後の表面
電位はそれぞれ＋700V，＋200Vとなつている。１
１は本発明による転写前コロナ放電器であり、現
像領域から転写領域に至るまでの間、即ち第１図
に示す領域Ａに配置されている。１２は放電電極
であり、電源１３により約6KVのトナーと同極
性、即ちここでは極性の高圧電圧が印加されて
いる。感光体側の放電器開口部には制御格子１４
としてφ60μ〜φ100μのタングステンワイヤー
が0.5〜２mm間隔に、感光ドラム表面から略１mm
離れて設けられており、これらはバイアス電源１
５に接続されている。 FIG. 2 is a configuration explanatory diagram showing an embodiment of the present invention. Components in the figure that are the same as those in FIG. 1 are given the same reference numerals. That is, 1 is a photosensitive drum, 8 is a transfer charger, and 9 is a transfer material. The surface of the photosensitive drum 1 has a dark area surface potential V D +800V and a bright area surface potential V
A latent image of L +200V is formed. The surface potentials after development are +700V and +200V, respectively. 1
Reference numeral 1 denotes a pre-transfer corona discharger according to the present invention, which is disposed between the development area and the transfer area, that is, the area A shown in FIG. Reference numeral 12 denotes a discharge electrode, to which a high voltage of approximately 6 KV having the same polarity as the toner, that is, the polarity here, is applied by a power source 13. A control grid 14 is provided at the opening of the discharger on the photoreceptor side.
Tungsten wires with a diameter of 60μ to 100μ are placed at intervals of 0.5 to 2mm, approximately 1mm from the surface of the photosensitive drum.
These are provided separately from the bias power supply 1.
5.
バイアス電圧は現像後の感光ドラムの明部電位
ＶLと暗部電位ＶDの間の電圧が選ばれる。これは
感光ドラムの表面電位と制御格子の間で、コロナ
イオンの促進電界と抑制電界とを形成するため
で、その結果暗部トナーをより負極性に帯電して
転写性を向上させている。現像後の感光ドラムの
明部電位がＶL＝＋200Vで暗部電位がＶD＝＋
700Vの時は一例として制御格子に＋400Vを印加
する。すると感光ドラムの暗部と制御格子との間
には300V／mmの転写前コロナ放電の促進電界が
形成され、明部と制御格子との間には200V／mm
の抑制電界が形成される。 As the bias voltage, a voltage between the bright area potential V L and the dark area potential V D of the photosensitive drum after development is selected. This is because a promoting electric field and a suppressing electric field for corona ions are formed between the surface potential of the photosensitive drum and the control grid, and as a result, the dark area toner is charged to a more negative polarity to improve transferability. The bright area potential of the photosensitive drum after development is V L = +200V, and the dark area potential is V D = +
For example, when the voltage is 700V, +400V is applied to the control grid. Then, an electric field promoting pre-transfer corona discharge of 300 V/mm is formed between the dark area of the photosensitive drum and the control grid, and an electric field of 200 V/mm is formed between the bright area and the control grid.
A suppressing electric field is formed.
次に第２図に示した転写前コロナ放電器をカー
ルソン電子写真法に適用した時の制御格子の作用
について述べる。 Next, the action of the control grid when the pre-transfer corona discharger shown in FIG. 2 is applied to Carlson electrophotography will be described.
第３図に明部部分Ｌの様子を示す。放電電極１
２で発生した負のコロナイオンは制御格子１４付
近に達するが、制御格子１４と感光体１との間に
形成される抑制電界E1＝200V／mmのため感光体
に達することができず、制御格子に捕集される。
このため画像明部に付着した帯電トナー１６や非
帯電トナー１７からなるカブリトナナーが負極性
に帯電されることはない。 FIG. 3 shows the bright area L. Discharge electrode 1
The negative corona ions generated in step 2 reach the vicinity of the control grid 14, but cannot reach the photoconductor because of the suppressing electric field E 1 =200V/mm formed between the control grid 14 and the photoconductor 1. collected on a control grid.
Therefore, the fog toner consisting of the charged toner 16 and the uncharged toner 17 attached to the bright areas of the image is not negatively charged.
第４図に暗部部分Ｄの様子を示す。 FIG. 4 shows the dark area D.
制御格子には約＋400Vのバイアスが印加され
ている。放電電極１２で発生した負のコロナイオ
ンは制御格子１４付近に達した後、制御格子１４
と感光体１との間に形成される促進電界E2＝
300V／mmに沿つて感光体表面に達し、画像暗部
のトナーをより負極性に帯電する。この結果暗部
トナーは十分負極性に帯電され、転写効率の向上
が図れる。 A bias of approximately +400V is applied to the control grid. After the negative corona ions generated at the discharge electrode 12 reach the vicinity of the control grid 14,
The promoting electric field E 2 formed between and the photoreceptor 1 =
It reaches the surface of the photoreceptor along 300V/mm and charges the toner in the dark areas of the image to a more negative polarity. As a result, the dark area toner is sufficiently negatively charged, and the transfer efficiency can be improved.
以上のようにして画像暗部のトナー極性をより
強い負極性にすることが可能になるため、転写率
が向上し、転写ムラのないコピー画像を得ること
ができる。又、従来の転写前コロナ放電器のよう
に環境に左右されるようなこともない。 As described above, it is possible to make the toner polarity in the dark part of the image more strongly negative, so that the transfer rate is improved and a copy image without uneven transfer can be obtained. Furthermore, unlike conventional pre-transfer corona dischargers, it is not affected by the environment.
なお本発明の実施例の説明に当つては、感光体
としてカールソン法による二層感光体を用いる例
を示したが、特公昭42―23910号公報等に記載の
電子写真法に使用されるような表面に絶縁層を有
する三層感光体の場合にも、本発明は適用できる
ものである。 In the explanation of the embodiments of the present invention, an example was shown in which a two-layer photoreceptor based on the Carlson method was used as the photoreceptor. The present invention is also applicable to a three-layer photoreceptor having an insulating layer on its surface.
以上述べたように、本発明では電子写真装置の
現像領域から転写領域に至る迄の領域に、トナー
と同極性の転写前コロナ放電器を配置し、この放
電器の開口部に設けた制御格子に感光体の暗部表
面電位ＶDと明部表面電位ＶLとの間の電圧をバイ
アス電圧として印加することとしたから、暗部ト
ナーは選択的により強く帯電され、明部部分は帯
電されることがない。従つてカブリがなく、暗部
トナー画像の転写性転写率が向上し、又環境変動
に左右されることのない転写前コロナ放電を行な
える効果を奏する。 As described above, in the present invention, a pre-transfer corona discharger having the same polarity as the toner is arranged in the area from the development area to the transfer area of the electrophotographic apparatus, and a control grid is provided at the opening of the discharger. Since a voltage between the dark area surface potential V D and the light area surface potential V L of the photoconductor is applied as a bias voltage, the dark area toner is selectively charged more strongly and the bright area is charged. There is no. Therefore, there is no fog, the transfer rate of dark toner images is improved, and corona discharge before transfer can be performed without being influenced by environmental changes.
第１図は従来の電子写真装置の概略図、第２図
は本発明の実施例を示す構成説明図、第３図・第
４図は本発明装置による作用を示す説明図であ
る。
図において、１…感光体、１１…転写前コロナ
放電器、１２…放電電極、１３…高圧電源、１４
…制御格子、１５…バイアス電源、１６…帯電ト
ナー、１７…非帯電トナーを表わす。
FIG. 1 is a schematic diagram of a conventional electrophotographic apparatus, FIG. 2 is a configuration explanatory diagram showing an embodiment of the present invention, and FIGS. 3 and 4 are explanatory diagrams showing the operation of the apparatus of the present invention. In the figure, 1... photoreceptor, 11... pre-transfer corona discharger, 12... discharge electrode, 13... high voltage power supply, 14
... Control grid, 15... Bias power source, 16... Charged toner, 17... Uncharged toner.
Claims (1)
た後転写材に転写して画像を得る電子写真装置に
おいて、現像領域から転写領域に至るまでの領域
に制御格子を有する転写前コロナ放電器を設け、
この放電器のコロナ放電極にトナー極性と同極性
の高圧電圧を印加し、制御格子に現像後の感光体
の暗部部分の電位ＶDと現像後の感光体の明部部
分の電位ＶLとの間にあるバイアス電圧を印加し
たことを特徴とする電子写真装置。1 In an electrophotographic device that forms an electrostatic latent image on a photoreceptor, develops it, and then transfers it to a transfer material to obtain an image, a pre-transfer corona having a control grid in the area from the development area to the transfer area Install a discharger,
A high voltage with the same polarity as the toner polarity is applied to the corona discharge electrode of this discharger, and the control grid is set to have the potential V D of the dark part of the photoconductor after development and the potential V L of the bright part of the photoconductor after development. An electrophotographic apparatus characterized in that a bias voltage between 1 and 2 is applied.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13691279A JPS5660452A (en) | 1979-10-22 | 1979-10-22 | Electrophotographic device |
| US06/191,030 US4402591A (en) | 1979-09-29 | 1980-09-26 | Electrophotographic apparatus |
| DE19803036731 DE3036731A1 (en) | 1979-09-29 | 1980-09-29 | ELECTROPHOTOGRAPHIC DEVICE |
| GB8031336A GB2062548B (en) | 1979-09-29 | 1980-09-29 | Electrophotographic apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13691279A JPS5660452A (en) | 1979-10-22 | 1979-10-22 | Electrophotographic device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5660452A JPS5660452A (en) | 1981-05-25 |
| JPS6226026B2 true JPS6226026B2 (en) | 1987-06-05 |
Family
ID=15186472
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13691279A Granted JPS5660452A (en) | 1979-09-29 | 1979-10-22 | Electrophotographic device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5660452A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3778940A1 (en) | 2019-08-15 | 2021-02-17 | Manufacture d'Horlogerie Audemars Piguet SA | Composite material, heterogeneous component for timepiece and method for manufacturing same |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6114674A (en) * | 1984-06-29 | 1986-01-22 | Canon Inc | Corona discharge device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5136950A (en) * | 1974-07-25 | 1976-03-29 | Xerox Corp | Seidenfukushaki |
| JPS53100239A (en) * | 1977-02-15 | 1978-09-01 | Olympus Optical Co Ltd | Obtaining a large number of transfer copies from a single latent image |
-
1979
- 1979-10-22 JP JP13691279A patent/JPS5660452A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5136950A (en) * | 1974-07-25 | 1976-03-29 | Xerox Corp | Seidenfukushaki |
| JPS53100239A (en) * | 1977-02-15 | 1978-09-01 | Olympus Optical Co Ltd | Obtaining a large number of transfer copies from a single latent image |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3778940A1 (en) | 2019-08-15 | 2021-02-17 | Manufacture d'Horlogerie Audemars Piguet SA | Composite material, heterogeneous component for timepiece and method for manufacturing same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5660452A (en) | 1981-05-25 |
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