Illumination control apparatus for controlling illumination by detecting external magnetic field

An illumination control apparatus for controlling illumination by detecting a change in an environment is provided. The illumination control apparatus includes a magnetic field detector for detecting a change in a magnetic field generated by a magnetized ferroelectric object to output a first signal having a voltage which is proportional to the change in the magnetic field; an amplifier for amplifying the first signal; a discriminator for discriminating a level of the amplified voltage to output an illumination on-signal having a first logic level if the level of the amplified voltage is higher than a predetermined voltage, and otherwise to output an illumination off-signal having a second logic level; an illumination controller for outputting an illumination driving voltage in response to the illumination on-signal having the first logic level; and an illumination portion for producing light in response to the illumination driving voltage. Thus, the illumination control apparatus can turn illumination on/off by detecting the approach of a key in any locking system for use in, for example, the front door of a house, cars or office supplies, which requires that the key made of a ferroelectric material is magnetized. Also, the illumination control apparatus can control illumination in response to a specific action of a user and can be easily installed in a limited space.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an illumination control apparatus, and 
more particularly, to an illumination control apparatus for controlling 
illumination by detecting an external magnetic field. The present 
application is based upon Korean Application No. 99-26741 filed on Jul. 3, 
1999, which is incorporated herein by reference. 
2. Description of the Related Art 
In apparatuses for controlling illumination by detecting a change in the 
environment, automatic illumination has been achieved by detecting a 
person approaching an area using the reflection of ultrasonic waves or 
infrared rays. However, such conventional illumination control methods 
cannot control illumination according to a specific need of a user, and 
are not suitable for illumination in a restricted small area. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an illumination control 
apparatus capable of controlling illumination in response to a specific 
action of a user. 
According to an aspect of the present invention, there is provided an 
illumination control apparatus for controlling the turn-on and turn-off of 
illumination by detecting a change in an environment, comprising a 
magnetic field detector for detecting a change in a magnetic field 
generated by a magnetized ferroelectric object to output a first signal 
having a voltage which is proportional to the change in the magnetic 
field; an amplifier for amplifying the first signal; a discriminator for 
discriminating a level of the amplified voltage to output an illumination 
on-signal having a first logic level if the level of the amplified voltage 
is higher than a predetermined voltage, and otherwise to output an 
illumination off-signal having a second logic level; an illumination 
controller for outputting an illumination driving voltage in response to 
the illumination on-signal having the first logic level; and an 
illumination portion for producing light in response to the illumination 
driving voltage. 
The magnetic field detector comprises a coil means for outputting an 
induced voltage proportional to the change in the magnetic field induced 
thereto as a first signal. The illumination control apparatus further 
comprises a light guiding element for guiding the produced light wherein 
the light is dispersed around a key boss. Preferably, the ferroelectric 
subject is a key, and the light guiding element is arranged to illuminate 
the peripheral region of the key boss.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, an illumination control apparatus 14 according to a 
preferred embodiment of the present invention comprises a magnetic field 
detector 142, an amplifier 144, a key detection discriminator 146, an 
illumination controller 148, an illumination portion 150 and a light 
guiding element 152. 
In the operation of the illumination control apparatus, the magnetic field 
detector 142 includes a coil into which a magnetic field 0 generated by a 
magnetized key 12 is applied. Also, a voltage .DELTA.V, which is 
proportional to a change of the magnetic field which is induced in the 
coil .DELTA.B, is induced across both ends of the coil. Thus, the magnetic 
field detector 142 detects a change in the magnetic field B, which is 
produced with the approach of the key 12, and outputs the induced voltage 
.DELTA.V as a first signal. 
Because the level of the induced voltage is as low as several microvolts to 
several millivolts, the first signal must be amplified. The amplifier 144, 
such as an operational (OP) amplifier, amplifies the first signal. If the 
amplified voltage is higher than a predetermined level, the key detection 
discriminator 146 determines that the key 12 is near by, and outputs an 
illumination on-signal having a first logic level. Otherwise, the key 
detection discriminator 146 determines that the key 12 is not near by, and 
outputs an illumination off-signal having a second logic level. 
Then, the illumination controller 148 receives a +5V external power voltage 
which is a high level, and outputs an illumination driving voltage having 
a transistor-transistor logic (TTL) level of 3V or more. The illumination 
portion 150 is turned on or off in response to the illumination driving 
voltage to emit light. The light guiding element 152, which is installed 
close to the illumination portion 150, is arranged in an annular shape, 
such that the light emitted from the illumination portion 150 is dispersed 
around a key boss 16 through the light guiding element 152. Thus, as a 
user brings the key 12 near the magnetic field detector 142, the key boss 
16 is illuminated, thereby allowing the user to easily insert the key 12 
into the key hole. 
The illumination control apparatus causes illumination in response to a 
specific action of a user, for example, bringing a key near a key hole, 
when the key is magnetized. Thus, the illumination control apparatus 
according to the present invention can be applied to any locking system 
for use in, for example, the front door, cars or office supplies, which 
requires a key made of a ferroelectric material being magnetized. Also, 
the illumination control apparatus, which is installed at a portion near 
the key boss, can be easily installed in a limited space, compared to a 
conventional illumination apparatus which requires a high sensitivity to 
sense the human body itself. 
While this invention has been particularly shown and described with 
reference to a preferred embodiment thereof where the object which 
produces a magnetic field is a key, it will be understood by those skilled 
in the art that various changes in form and details may be made therein 
without departing from the spirit and scope of the invention as defined by 
the appended claims, wherein for example, any object made of ferroelectric 
material which generates a relatively strong magnetic field when it is 
magnetized, may be used.