Compact electronic apparatus with a refresh unit for a dynamic type memory

• US 4,881,205 A
• Filed: 04/14/1988
• Issued: 11/14/1989
• Est. Priority Date: 04/21/1987
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Aihara, Toshiharu
• Primary Examiner(s): Gossage, Glenn A.
• Application Number:
  US07/181,444
• Time in Patent Office: 579 Days
• Field of Search: 365/222, 365/233, 365/230, 365/227, 365/228, 365/45, 379/67, 379/88, 364/707
• US Class Current: 365/222
• CPC Class Codes: G11C 11/406 Management or control of the refreshing or charge-regeneration cycles

Abstract

A compact electronic apparatus employs a dynamic type memory, e.g., a dynamic random access memory (DRAM), a crystal oscillator circuit for generating a high frequency signal, and a resistor/capacitor (RC) circuit for generating a low frequency signal. When the apparatus is operated, the high frequency signal is used for accessing the data stored in the DRAM. When operation of the apparatus is interrupted, the DRAM is refreshed by the low frequency signal thus reducing the entire power consumption of the apparatus, since the power consumption of the RC oscillator circuit is lower than that of the crystal oscillator circuit.

Claims

1. A compact electronic apparatus having a refresh unit for a dynamic type memory, comprising:

a battery power source;

first oscillator means for generating a relatively high frequency signal;

second oscillator means for generating a relatively low frequency signal with respect to said high frequency signal;

a dynamic type memory required to be refreshed during a non-access time period;

first switch means coupled between said battery power source and said first oscillator means, for applying a battery voltage derived from said battery power source to said first oscillator means;

second switch means coupled between said battery power source and said second oscillator means, for applying the battery voltage obtained from said battery power source to said second oscillator means;

external operation switch means for starting an accessing operation of said dynamic type memory;

first output control means for actuating said first oscillator means, including means for applying said battery voltage to said first oscillator means when said first switch means is turned ON by operation of said external operation switch means, wherein said high frequency signal is generated;

memory access means for accessing said dynamic type memory in response to said high frequency signal derived from said first oscillator means; and

second output control means for turning OFF said first switch means during a non-accessing operation time period of said dynamic type memory and interrupting the oscillation of said first oscillator means, and for simultaneously turning ON said second switch means to actuate said second oscillator means, wherein said low frequency signal derived from said second oscillator means is output in the form of a refresh signal for said dynamic type memory.

2. A compact electronic apparatus claimed in claim 1, wherein said first oscillator means is a crystal oscillator circuit.

3. A compact electronic apparatus as claimed in claim 1, wherein said second oscillator means is a resistor and capacitor oscillator circuit.

4. A compact electronic apparatus as claimed in claim 1, wherein said dynamic type memory is a dynamic random access memory.

5. A compact electronic apparatus having a refresh unit for a dynamic type memory, comprising:

a battery power source;

first oscillator means for generating a relatively high frequency signal;

second oscillator means for generating a relatively low frequency signal with respect to said high frequency signal;

first switch means coupled between said battery power source and said first oscillator means, for applying a battery voltage derived from said battery power source to said first oscillator means;

second switch means coupled between said battery power source and said second oscillator means, for applying the battery voltage obtained from said battery power source to said second oscillator means;

first converting means for converting an externally provided voice sound into voice data;

a dynamic memory coupled to said first converting means for storing said voice data therein, said memory being required to be refreshed for holding the stored voice data;

write control means coupled to said first converting means, for enabling the storing of said voice data in said dynamic memory;

second converting means coupled to said dynamic memory for converting said voice data stored in said dynamic memory into a voice signal;

voice reproducing means coupled to said second converting means for reproducing said voice signal to generate a voice sound;

externally operative switch means coupled to the dynamic memory for enabling writing and reading of said voice data;

first control means coupled to said externally operative switch means for turning ON said first switch means to output said high frequency signal from said first oscillator means, and for storing said voice data by accessing said dynamic memory in response to said relatively high frequency derived from said first oscillator means; and

second control means coupled to said externally operative switch means for turning OFF said first switch means and interrupting the oscillation of said first oscillator means, and for holding the stored voice data by refreshing said dynamic memory in response to the low frequency signal derived from said second oscillator means.

6. A compact electronic apparatus as claimed in claim 5, wherein said first oscillator means is a crystal oscillator circuit.

7. A compact electronic apparatus as claimed in claim 5, wherein said second oscillator means is a resistor and capacitor oscillator circuit.

8. A compact electronic apparatus as claimed in claim 5, wherein said dynamic memory is a dynamic random access memory.

9. A compact electronic apparatus having a refresh unit for a dynamic type memory, comprising:

a battery power source;

first oscillator means for generating a relatively high frequency signal;

second oscillator means for generating a relatively low frequency signal with respect to said high frequency signal;

first switch means coupled between said battery power source and said first oscillator means, for applying a battery voltage derived from said battery power source to said first oscillator means;

second switch means coupled between said battery power source and said second oscillator means, for applying the battery voltage obtained from said battery power source to said second oscillator means;

data input means including entry keys for entering at least numerical data;

a dynamic memory coupled to said data input means for storing said numerical data entered by said data input means;

first control means coupled to the dynamic memory, said first switch means and said data input means, for turning ON said first switch means to output said high frequency signal from said first oscillator means, and for accessing said dynamic memory in response to said high frequency signal derived from said first oscillator means; and

second control means coupled to the dynamic memory and the first switch means for turning OFF said first switch means and interrupting the oscillation of said first oscillator means, and for refreshing said dynamic memory in response to the low frequency signal derived from said second oscillator means.

10. A compact electronic apparatus as claimed in claim 9, wherein said first oscillator means is a crystal oscillator circuit.

11. A compact electronic apparatus as claimed in claim 9, wherein said second oscillator means is a resistor and capacitor oscillator circuit.

12. A compact electronic apparatus as claimed in claim 9, wherein said dynamic memory is a dynamic random access memory.