Bar code reader

In a bar code reader having a light source for lighting the bar code, an image sensor for receiving the reflected light from the bar code and producing an image signal, a drive circuit for driving the image sensor, an amplifier for amplifying the image signal, and a digitalizing circuit for digitalizing the amplified image signal and producing a digital signal representing the bar code, an improvement comprising:

• said image sensor comprising light receiving elements formed in a CCD array which operates with an operating voltage Vcc less than 8 V;
• said amplifier comprising first and second operational amplifiers each having one voltage source terminal connected to Vcc of 5 V and the other voltage source terminal connected to ground;
• said digitalizing circuit comprising a third operational amplifier having one voltage source terminal connected to Vcc of 5 V and the other voltage source terminal connected to ground;
• and
• amplitude control means for controlling the amplitude of the amplified image signal, said amplitude control means comprising (i) a fourth operational amplifier coupled to said amplifier, and (ii) means to which said fourth operational amplifier is coupled for changing an amplification rate of said fourth operational amplifier as a function of a bar code detection signal.