# US 2014/0191817 A1 · Pwm signal generating circuit, printer, and pwm signal generating method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191817 A1 - Document ID: US20140191817A1 - Status: Published application - Kind: A1 - Application number: 14/141,860 - Filed: 2013-12-27 - Published: 2014-07-10 - Earliest claimed: 2013-01-07 - Assignees: Ricoh Company, Ltd. - Inventors: Takashi MICHIYOSHI; Tetsuro TATEBE - Web page: https://patentgrep.com/patent/US20140191817A1 ## CPC - H03K 7/08: Duration or width modulation {; Duty cycle modulation} - G03G 15/043: with means for controlling illumination or exposure (G03G15/041 takes precedence) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A PWM signal generating circuit, printer, and PWM signal generating method are described. The PWM signal generating circuit includes: a single counter configured to count values expressed in N bits; and at least one arithmetic device configured to generate a PWM signal, each of the at least one arithmetic device including a pulse width data storage unit for storing N-bit pulse width data representing a pulse width of the PWM signal to be generated, and an adder for calculating a carry value from a most significant bit obtained when adding the count value and the pulse width data. A signal having a level corresponding to the carry value is output at every change in the count value so that the PWM signal having the pulse width of the pulse width data is generated. ## Claims ### Claim 1 A PWM signal generating circuit, comprising: a single counter configured to count values expressed in N bits; and at least one arithmetic device configured to generate a PWM signal, each of the at least one arithmetic device including: a pulse width data storage unit for storing N-bit pulse width data representing a pulse width of the PWM signal to be generated; and an adder for calculating a carry value from a most significant bit obtained when adding the count value and the pulse width data, wherein a signal having a level corresponding to the carry value is output at every change in the count value so that the PWM signal having the pulse width of the pulse width data is generated. ### Claim 2 (depends on 1) The PWM signal generating circuit according to claim 1, wherein the adder does not calculate a sum of the count value and the pulse width data. ### Claim 3 (depends on 1) The PWM signal generating circuit according to claim 1, wherein the counter generates an enable bit indicating that count is performed, and the adder uses the enable bit as a carry value to a least significant bit. ### Claim 4 (depends on 1) The PWM signal generating circuit according to claim 1, wherein the counter is an up counter. ### Claim 5 (depends on 1) The PWM signal generating circuit according to claim 1, wherein the counter s a down counter. ### Claim 6 (depends on 1) The PWM signal generating circuit according to claim 1, wherein the counter s an up-down counter. ### Claim 7 (depends on 6) The PWM signal generating circuit according to claim 6, wherein the counter counts only one of an even number value and an odd number value in the count values expressed in the N bits in an up-count operation and counts only the other in a down-count operation. ### Claim 8 (depends on 1) The PWM signal generating circuit according to claim 1, wherein, when the at least one of arithmetic device includes a plurality of arithmetic devices, the pulse width data storage units of the plurality of arithmetic devices respectively store pulse width data representing different pulse widths, and the arithmetic devices respectively generate the plurality of PWM signals having the different pulse widths. ### Claim 9 (depends on 8) A printer comprising: a photoreceptor; the PWM signal generating circuit according to claim 8; a plurality of light sources configured to irradiate the photoreceptor n a predetermined light quantity; and a plurality of driver circuits configured to drive the light sources, wherein the plurality of PWM signals are input to the driver circuits respectively and control the light quantities of the light sources respectively. ### Claim 10 A PWM signal generating method, performed by a PWM signal generating circuit including a single counter and at least one arithmetic device, the method comprising: storing, in each of the at least one arithmetic device, N-bit pulse width data representing a pulse width of the PWM signal to be generated; generating a count value expressed in N bits by using the counter; and calculating a carry value from a most significant bit obtained when adding the count value and the pulse width data by using each of the at least one arithmetic device, wherein a signal having a level corresponding to the carry value is output at every change in the count value so that the PWM signal having the pulse width of the pulse width data is generated.