EP0288292A2
Expired / Lapsed
EP
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Electronic control circuit for preventing abnormal operation of a slave control circuit
Assignee: Brother Industries Ltd
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Filing: 1988-04-21
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Granted: —
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Expires: 2008-04-21
Abstract
Abstract In an electronic control system having a main CPU (20) and a slave CPU (40,50) which is under the control of the main CPU (20), a power control circuit (10) is provided between the power source (Vc) and the slave CPU (40,50) to stop supplying power to the slave CPU (40,50) until the main CPU (20) starts normal operation when the power to the overall system is turned on. The slave CPU (40,50) does not start operation until the main CPU (20) becomes capable of normal operation and control over the slave CPU, which prevents unexpected action of the slave CPU and the subordinate control object. The power control circuit (10) is also effective in preventing the abnormal action of the slave CPU when the power to the overall system is turned off. The system is applicable to a system in which the slave circuit is a display driver for a liquid crystal display
Inventors
- 👤 Kiyoshi Yamakawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 05:02
CPC Classifications
G; G06; G06F; G06F1/00; G06F1/24; G06F1/26
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
99 words
An electronic control circuit comprising: a main control circuit (20) which is connected to a power source (Vc); and a slave control circuit (40,50) which is under control of the main control circuit (20) and is connected to the power source (Vc); and a power control circuit (10) provided between the power source (Vc) and the slave control circuit (40,50) for inihibiting power supply to the slave control circuit (40,50) while the output of the power source is lower than a predetermined value, the predetermined value being determined based on a minimum requirement of the main control circuit (20).
Claim 2
Dependent Claim
99 words
An electronic control circuit comprising: a main control circuit (20) which is connected to a power source (Vc); and a slave control circuit (40,50) which is under control of the main control circuit (20) and is connected to the power source (Vc); and a power control circuit (10) provided between the power source (Vc) and the slave control circuit (40,50) for inihibiting power supply to the slave control circuit (40,50) while the output of the power source is lower than a predetermined value, the predetermined value being determined based on a minimum requirement of the main control circuit (20).
Claim 3
Dependent Claim
40 words
An electronic control circuit according to claim 1 wherein the power supply is inhibited while the output voltage of the power supply is lower than a predetermined voltage value based on the minimum operable voltage of the main control circuit.
Claim 4
Dependent Claim
61 words
An electronic control circuit according to claim 1 or 2 wherein the power control circuit (10) comprises a first switching transistor (Tr1) and a second switching transistor (Tr2), the first switching transistor being provided for switching the second switching transistor depending on the predetermined value and the second switching transistor being provided for switching power supply to the slave control circuit.
Claim 5
Dependent Claim
40 words
An electronic control circuit according to claim 3 wherein the power control circuit (10) further comprises a first resistance (11) and a second resistance (12) both sequentially provided between the power source and a ground for generating the predetermined value.
Claim 6
Dependent Claim
22 words
An electronic control circuit according to claim 1, 2 or 3 wherein the predetermined value is generated by the main control circuit.
Claim 7
Dependent Claim
51 words
An electronic control circuit according to claim 1 or 2 wherein the power control circuit (10) comprises a reference diode (ZD) and a switching transistor (Tr2), the reference diode being provided for determining the predetermined value and the switching transistor being provided for switching power supply to the slave control circuit.
Claim 8
Dependent Claim
96 words
A liquid crystal display control circuit for use with a liquid crystal display (100) and a display driver (102, 104, 106, 108, 110) connected to the liquid crystal display, the liquid crystal display control circuit comprising: a power control circuit (130) provided, in use, between a power source (115) and the liquid crystal display (100) for inhibiting power supply to the liquid crystal display (100) while a voltage level of the power source (115) is lower than a predetermined value, the predetermined value being determined based on a voltage below which the display driver is inoperable.
Claim 9
Dependent Claim
96 words
A liquid crystal display control circuit for use with a liquid crystal display (100) and a display driver (102, 104, 106, 108, 110) connected to the liquid crystal display, the liquid crystal display control circuit comprising: a power control circuit (130) provided, in use, between a power source (115) and the liquid crystal display (100) for inhibiting power supply to the liquid crystal display (100) while a voltage level of the power source (115) is lower than a predetermined value, the predetermined value being determined based on a voltage below which the display driver is inoperable.
Claim 10
Dependent Claim
62 words
The liquid crystal display control circuit according to claim 7, wherein the power control circuit (130) comprises a first switching transistor (Tr1) and a second switching transistor (Tr2), the first switching transistor being provided for switching the second switching transistor depending on the predetermined value and the second switching transistor being provided for switching the power supply to the liquid crystal display.
Claim 11
Dependent Claim
45 words
The liquid crystal display control circuit according to claim 8, wherein: the liquid crystal display control circuit comprises a CPU (135) connected to the power source and having a reset terminal; and the first switching transistor is switched by a signal from the reset terminal.
Claim 12
Dependent Claim
30 words
Apparatus incorporating a control circuit according to any one of claims 1 to 6 or a liquid crystal display control circuit according to any one of claims 7 to 9.
References Cited (Backward Citations)
No citation records indexed.
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