Abstract:
A decorative tree uses a control circuit to operate multiple light strings and a speaker. Based on different types of music output by the speaker, the control circuit determines the light strings to be properly turned on or off. Therefore, the visual effects generated by these light strings coordinate with the output music.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a decorative tree and, in particular, to a decorative tree capable of simultaneously generating visual and sound effects coordinating with each other. 
   2. Description of Related Art 
   Electronic ornaments are developed and manufactured in recent years to enrich decorative effects. For example, a conventional Christmas tree may leave people with a monotonous impression even though colorful bulbs are decorated on the tree. Therefore, an optical fiber-based Christmas tree can generate superior visual effects than the conventional type. Such an optical fiber-based Christmas uses optical fibers as a tree frame and comprises a base and a light color changing assembly. The light color changing assembly is composed a light source, a colorful rotating disk and a motor. The light source is mounted below the rotating disk, and the rotating disk is driven by the motor. Since the rotating disk with different color regions is made of transparent material, a source light beam emitting through the rotating disk becomes a colored light beam to be guided into multiple optical fibers. As the motor drives the rotating disk, the color of the light beam guided into the optical fibers is accordingly changed. 
   Even though the optical fiber-based Christmas tree can change the colors of the light beam, it still has the disadvantages of high power consumption and complex structure. Further, since the rotating disk is driven with a constant speed and has only limited color regions, the Christmas tree therefor will easily lose its decorative effect. 
   SUMMARY OF THE INVENTION 
   An objective of the invention is to provide a decorative tree that is capable of generating visual effects based on characteristics of sound effects such as music rhythm, tone and instrument. With the visual effects in coordination with the sound effects, the decorative effects of the tree can be enriched. 
   To achieve the above-mentioned objective, the decorative tree provides a control circuit to operate multiple light strings and a speaker. Based on different types of music output by the speaker, the control circuit determines the light strings to be properly turned on or off. Therefore, the visual effects generated by these light strings coordinates with the output music. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a decorative tree in accordance with the present invention; 
       FIG. 2  is a block diagram of a control circuit for the decorative tree in accordance with the present invention; and 
       FIGS. 3A-3D  show a circuit diagram of the control circuit of  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIG. 1 , a decorative tree of the present invention comprises a base ( 10 ), a tree-like stand ( 11 ) mounted on the base ( 10 ), multiple light strings ( 12 ) mounted on the tree-like stand ( 11 ) and a control box ( 20 ) connected to the light strings ( 12 ). Each of the light strings ( 12 ) is formed by multiple lighting elements. 
   The control box ( 20 ) determines the operations of the light strings ( 12 ) and connects with a wire ( 21 ) to receive an AC power. The control box ( 20 ) further equips with a speaker ( 23 ) to output sounds. 
   With reference to FIGS.  2  and  3 A- 3 D, a circuit of the control box ( 20 ) comprises a voltage transformer ( 30 ), multiple control switches ( 32 ), multiple thyristors (TRIAC) ( 33 ), a central control circuit ( 34 ) and an audio amplify circuit ( 35 ). 
   The voltage transformer ( 30 ) is connected to the wire ( 21 ) to transform an input AC voltage to a first DC voltage. The first DC voltage is output to a voltage regulating circuit ( 31 ). The voltage regulating circuit ( 31 ), which can be an integrated circuit (IC), further transforms the incoming first DC voltage to a second DC voltage. In this embodiment the first DC voltage is 12 volts and the second DC voltage is 5 volts. 
   Each of the control switches ( 32 ) is connected between the output terminal of the voltage regulating circuit ( 31 ) and a respective thyristor ( 33 ), and has a control terminal in connection with the central control circuit ( 34 ). The control switch ( 32 ) can be implemented by a NPN transistor as shown in this embodiment, wherein a collector, an emitter and a base of the NPN transistor are respectively connect to the voltage regulating circuit ( 31 ), the respective thyristor ( 33 ) and the central control circuit ( 34 ). 
   Each of the multiple thyristors ( 33 ) has a first terminal, a second terminal and a trigger terminal. The first terminals of the multiple thyristors ( 33 ) connect to the multiple light strings ( 12 ) respectively. All the second terminals are connected to a ground. The trigger terminals are respectively connected to the control switches ( 32 ). 
   The central control circuit ( 34 ) can be implemented by an integrated circuit (IC). The central control circuit ( 34 ) has a voltage terminal connected to the output terminal of the voltage regulating circuit ( 34 ), multiple control signal output terminals (CT 1  to CT 11 ) respectively connected to the bases of the control switches ( 32 ), and an audio signal output terminal connected to the audio amplify circuit ( 35 ). The central control circuit ( 32 ) further connects with a power switch ( 36 ). When the power switch ( 36 ) is pressed, the central control circuit ( 34 ) is activated. 
   The audio amplify circuit ( 35 ) has an input terminal in connection with the audio signal output terminal of the central control circuit ( 34 ) and an output terminal coupled to the speaker ( 23 ). 
   When the central control circuit ( 34 ) outputs audio signals to the audio amplify circuit ( 35 ), the amplified audio signal processes and amplifies these audio signals and then further transmits to the speaker ( 23 ) to generate desired sound effects. The central control circuit ( 34 ) simultaneously, based on the audio signals, correspondingly outputs drive signals from its terminals (CT 1  to CT 11 ) to turn on the respective control switches ( 32 ). When the control switches ( 32 ) are turned on, a trigger voltage is input to the trigger terminals of the thyristors ( 33 ) corresponding to these control switches ( 32 ) to activate the thyristors ( 33 ). When the thyristors ( 33 ) are activated, a path is formed between the output of the voltage transformer ( 30 ). With the path, a current flows through the light string ( 12 ) to turn on the lighting elements. 
   In the present invention, the central control circuit ( 34 ) determines the sounds and lighting of the decorative tree. Therefore, according to different factors of music to be output, such as rhythm, tone and instrument, the light strings ( 12 ) are correspondingly turned on or turned off to generate a visual effect that coordinates with the sound effect. As an example, for strong and fast music rhythm, a higher operating frequency for the light strings is preferable to rapidly turn on or turn off the lighting elements. In addition to the operating frequency of the light strings, the multiple light strings can be selectively activated with a desired sequence.