发明名称 |
ARITHMETICAL TEACHING AID |
摘要 |
Numeral labeled indicator lamps are sequentially illuminated and extinguished on a panel to display addition or subtraction operation. The quantity added or subtracted is selected by a pulse transmitting dialing machine. A reversing switch controls the direction in which the pulse advances a step switch to sequentially operate the indicator lamp in an addition or subtraction mode.
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申请公布号 |
US3688416(A) |
申请公布日期 |
1972.09.05 |
申请号 |
USD3688416 |
申请日期 |
1970.08.31 |
申请人 |
BARBARA KOENIG;CHRISTOPHER E. PFANNKUCHE |
发明人 |
BARBARA KOENIG;CHRISTOPHER E. PFANNKUCHE |
分类号 |
G09B19/02;(IPC1-7):G09B19/02 |
主分类号 |
G09B19/02 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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