| Patents for B43L 21 - Blackboard or slate-cleaning devices (5,409) |
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| 04/19/2000 | CN1051501C 写字板 WordPad |
| 04/12/2000 | CN2373285Y Bush-type chalk-dust absorbing apparatus |
| 04/12/2000 | CN2373284Y Electric eraser with dust collection function |
| 04/11/2000 | US6048121 Dry marker and eraser system |
| 04/05/2000 | CN2372156Y Electric dust absorption blackboard eraser |
| 04/05/2000 | CN2372155Y Dust-free blackboard eraser |
| 04/05/2000 | CN2372154Y Blackboard eraser |
| 03/29/2000 | CN2371047Y Chalk dust absorbing blackboard eraser |
| 03/22/2000 | CN2369878Y 吸尘黑板擦 Eraser dust |
| 03/22/2000 | CN2369877Y 电动黑板刷 Electric blackboard brush |
| 03/15/2000 | EP0985604A1 A sheet assembly |
| 03/15/2000 | CN2368726Y Dustless eraser |
| 03/15/2000 | CN2368725Y Dust collecting eraser |
| 03/15/2000 | CN2368724Y Electric blackboard eraser |
| 03/15/2000 | CN2368723Y Dust collector for blackboard eraser |
| 03/15/2000 | CN2368722Y 多功能黑板擦 Multifunction eraser |
| 03/08/2000 | CN2367480Y Electric eraser |
| 03/01/2000 | CN2366292Y Black board eraser with chalk-dust collector |
| 03/01/2000 | CN2366291Y Blackboard eraser |
| 02/23/2000 | CN2365085Y Electric sucking dust blackboard eraser |
| 02/23/2000 | CN2365084Y Sliding eraser for blackboard |
| 02/16/2000 | CN2363901Y Electric dust-collection blackboard eraser |
| 02/16/2000 | CN2363900Y 辊式防尘黑板擦 Roll eraser dust |
| 02/09/2000 | CN2362715Y 无尘黑板擦 Clean eraser |
| 02/02/2000 | CN2361492Y Dustless eraser |
| 02/02/2000 | CN2361491Y Electric eraser |
| 02/02/2000 | CN2361490Y Electrostatic eraser |
| 02/02/2000 | CN2361489Y Electric and hand eraser device |
| 02/02/2000 | CN2361488Y Eraser capable of drawing circle |
| 01/26/2000 | CN2360279Y Dustless eraser |
| 01/26/2000 | CN2360278Y Gloves type eraser |
| 01/19/2000 | CN2359137Y Electric eraser |
| 01/19/2000 | CN2359136Y New-type eraser |
| 01/19/2000 | CN2359131Y 空气屏式教学黑板 Air-screen blackboard teaching |
| 01/05/2000 | CN2356871Y Multifunctional chalk erazer |
| 01/05/2000 | CN2356870Y Electric chalk dust absorbing blackboard erazer |
| 01/05/2000 | CN2356869Y Self-absorption blackboard erazer |
| 01/05/2000 | CN2356868Y Improved dust-absorbing black (white) board structure |
| 01/05/2000 | CN2356867Y Electric dusting blackboard erazer |
| 12/29/1999 | CN2355900Y Dust absorbing blackboard eraser |
| 12/29/1999 | CN2355899Y Dust absorbing eraser |
| 12/29/1999 | CN2355898Y 无尘黑板擦 Clean eraser |
| 12/28/1999 | US6007891 Message board eraser, eraser holder and attaching mechanism |
| 12/22/1999 | CN2354780Y Drum style dust-collecting blackboard eraser |
| 12/22/1999 | CN2354779Y Electric dust collecting blackboard eraser |
| 12/22/1999 | CN2354778Y Automatic dust collecting blackboard eraser |
| 12/15/1999 | CN2353562Y Chalk-dust suction blackboard eraser |
| 12/15/1999 | CN2353561Y Blackboard cleaning machine |
| 12/08/1999 | CN2352369Y Hong holder blackboard eraser |
| 12/08/1999 | CN2352368Y Battery-charging type electric blackboard eraser with chalk dust absorbing |
| 12/08/1999 | CN2352367Y Blackboard eraser with means for absorbing chalk dust |
| 12/01/1999 | CN2351299Y Cleaning non-dust blackboard brush |
| 11/24/1999 | CN2350216Y Automatic chalk dust absorbing machine |
| 11/24/1999 | CN2350215Y Quick dustless noiseless double-purpose automatic blackboard eraser |
| 11/24/1999 | CN2350214Y Folding blackboard eraser |
| 11/24/1999 | CN2350213Y Blackboard cleaning device capable of screening dust |
| 11/23/1999 | US5989676 Bulletin board notepad holder and notepad holder attaching mechanism |
| 11/21/1999 | CA2272315A1 Combination dust, lint and dry erasing brush |
| 11/17/1999 | CN2349033Y Active blackboard eraser |
| 11/17/1999 | CN2349029Y Black (white) board structure with automatic rotation erasing |
| 11/10/1999 | CN2347788Y Eraser with chalk dust absorbing device |
| 11/10/1999 | CN2347787Y Eraser capable of absorbing chalk dust |
| 11/10/1999 | CN2347786Y Eraser with means for absorbing chalk dust |
| 11/02/1999 | US5976663 Bulletin board accessories and accessory attaching mechanism |
| 10/27/1999 | CN2345372Y Automatic dust-absorption eraser |
| 10/27/1999 | CN2345371Y Automatic dust-absorption eraser |
| 10/27/1999 | CN2345370Y Eraser |
| 10/27/1999 | CN2345369Y Multifunction eraser |
| 10/21/1999 | WO1999053466A2 An apparatus and a method for automatically erasing a blackboard |
| 10/20/1999 | CN2344193Y Electric dust-collecting eraser |
| 10/20/1999 | CN2344192Y Dust-free eraser |
| 10/13/1999 | CN2342997Y Chalk dust-absorbing blackboard eraser |
| 10/13/1999 | CN2342996Y Chalk dust-absorbing blackboard eraser |
| 09/29/1999 | CN2340626Y Dry dust-collecting blackboard eraser |
| 09/28/1999 | US5957700 Writing board |
| 09/28/1999 | US5957603 Combination support and eraser for a dry erase marker |
| 09/21/1999 | US5955170 Bulletin board mail holder and mail holder attaching mechanism |
| 09/15/1999 | CN2338181Y Chalk dust absorbing blackboard eraser |
| 09/15/1999 | CN2338180Y Electric chalk dust absorbing blackboard eraser |
| 09/01/1999 | CN2335799Y Dustless eraser |
| 08/25/1999 | CN2334604Y Squeezing type blackboard eraser |
| 08/18/1999 | CN2333553Y Dustproof eraser |
| 08/11/1999 | CN2332588Y Dust collecting eraser |
| 08/11/1999 | CN2332587Y Novel eraser |
| 08/11/1999 | CN2332586Y Multifunctional dust collecting eraser |
| 07/27/1999 | US5928756 Bulletin board accessories and accessory attaching mechanism |
| 07/14/1999 | CN2328531Y 除尘黑板刷 Dust blackboard brush |
| 07/07/1999 | CN2327543Y Blackboard eraser |
| 07/07/1999 | CN2327542Y Blackboard eraser with handle |
| 06/30/1999 | CN2326455Y Ash-collecting blackboard eraser |
| 06/30/1999 | CN2326454Y Eraser extension apparatus for eraser-type automatic erasing blackboard |
| 06/30/1999 | CN2326453Y Self-cleaning type whiteboard eraser |
| 06/23/1999 | CN2325235Y 无尘黑板擦 Clean eraser |
| 06/16/1999 | CN2323984Y Blackboard cleaning machine with means for absorbing the chalk dust |
| 06/16/1999 | CN2323983Y Automatic cleaning machine for blackboard |
| 06/09/1999 | CN2322803Y Chalk dust suction blackboard eraser |
| 06/08/1999 | US5910351 Multi-purpose hook |
| 05/26/1999 | CN2320431Y Remote-control automatic ohalk dust removing eraser |
| 05/26/1999 | CN2320430Y Dust remover of automatic chalk dust absorbing eraser |
| 05/19/1999 | CN2319231Y Dust sucking electromagnetic eraser |