Magnetic-head short-circuit detector

• US 6,104,199 A
• Filed: 10/29/1998
• Issued: 08/15/2000
• Est. Priority Date: 10/30/1997
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Sako, Michiya
• Primary Examiner(s): Ballato, Josie
• Assistant Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US09/181,805
• Time in Patent Office: 656 Days
• Field of Search: 324/537, 324/546, 324/547, 324/210, 324/211
• US Class Current: 324/546
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults

Abstract

A magnetic-head short-circuit detector for correctly detecting an electrical short-circuit between coil terminals of a magnetic head. Terminals H_X and H_Y of the magnetic head are connected to the bases of a pnp-transistors P₁ and P₂ respectively. Current sources I₁ and I₂ are inserted between power supply V_CC and the emitters of the transistors P₁ and P₂ respectively. The emitter of the transistor P₁ is connected to the (-) input terminal of a comparator 1 through a resistor R₁ and directly to the (+) input terminal of a comparator 2. The emitter of the transistor P₂ is connected to the (+) input terminal of the comparator 1 through a resistor R₂ and directly to the (-) input terminal of the comparator 2. A current source I₃ is connected between the (-) input terminal of the comparator 1 and GND. A current source I₄ is connected between the (input terminal of the comparator 2 and GND. Based on results of the comparison by the comparator 1 and the comparator 2, a short-circuit on the magnetic head is detected.

Claims

1. A magnetic-head short-circuit detector comprising:

first voltage and second voltage generating means for generating a first voltage corresponding to a voltage that appears at one end of a magnetic-head coil when a magnetic head is in a recording state and a second voltage having a predetermined potential difference relative to said first voltage;

third voltage and fourth voltage generating means for generating a third voltage corresponding to a voltage that appears at another end of said magnetic-head coil when said magnetic head is in said recording state and a fourth voltage having a predetermined potential difference relative to said third voltage;

first comparing means for comparing said first voltage with said fourth voltage; and

second comparing means for comparing said second voltage with said third voltage;

wherein a short circuit between both ends of said magnetic-head coil is detected based on a result of the comparison by said first comparing means and a result of the comparison of said second comparing means.

2. The magnetic-head short-circuit detector as claimed in claim 1, further comprising:

conjunction means for obtaining conjunction between the result of the comparison by said first comparing means and the result of the comparison by said second comparing means;

wherein, based on a result of said conjunction, a short-circuit between both ends of said magnetic-head coil is detected.

3. The magnetic-head short-circuit detector as claimed in claim 1, wherein said predetermined potential difference between said first voltage and said second voltage is set by a first resistor inserted between said first voltage and said second voltage and a first current source arranged so that current flows to said first resistor.

4. The magnetic-head short-circuit detector as claimed in claim 1, wherein said predetermined potential difference between said third voltage and said fourth voltage is set by a second resistor inserted between said third voltage and said fourth voltage and a second current source arranged so that current flows to said second resistor.

5. The magnetic head short-circuit detector as claimed in claim 2 further comprising:

a flip-flop with an input connected to output of said conjunction means; and

the clock of said flip-flop connected to a sampling signal,

thereby resulting in stable detection of said gate'"'"'s level.

6. A magnetic-head short-circuit detector comprising:

first voltage and second voltage generators for generating a first voltage corresponding to a voltage that appears at one end of a magnetic-head coil when a magnetic head is in a recording state and a second voltage having a predetermined potential difference relative to said first voltage;

third voltage and fourth voltage generators for generating a third voltage corresponding to a voltage that appears at another end of said magnetic-head coil when said magnetic head is in said recording state and a fourth voltage having a predetermined potential difference relative to said third voltage;

first comparator for comparing said first voltage with said fourth voltage; and

second comparator for comparing said second voltage with said third voltage;

wherein a short circuit between both ends of said magnetic-head coil is detected based on a result of the comparison by said first and second comparators.

7. The magnetic head short-circuit detector as claimed in claim 6, further comprising:

a gate which obtains conjunction between the result of the comparison by said first comparator and the result of the comparison by said second comparator means;

wherein, based on a result of said conjunction, a short-circuit between both ends of said magnetic head coil is detected.

8. The magnetic head short-circuit detector as claimed in claim 6, wherein said predetermined potential difference between said first voltage and said second voltage is set by a first resistor inserted between said first voltage and said second voltage and a first current source arranged so that current flows to said first resistor.

9. The magnetic head short-circuit detector as claimed in claim 6, wherein said predetermined potential difference between said third voltage and said fourth voltage is set by a second resistor inserted between said third voltage and said fourth voltage and a second current source arranged so that current flows to said second resistor.

10. The magnetic head short-circuit detector as claimed in claim 7 further comprising a flip-flop, connected to output of said gate and also to a sampling signal, for stable detection of said gate'"'"'s level.