Fuji Xerox Co., Ltd.

Nec Corporation

Sunao Ishizaki

Yoshifumi Takebe

Tomoharu Hieda

An image reading apparatus includes an image reading unit and a computational unit. The image reading unit includes a reference reflecting member that acts as a color reference, an illuminating unit that illuminates a part of the reference reflecting member and a sheet being transported in proximity thereto, a line sensor that reads an image formed on the sheet and the part of the reference reflecting member in proximity to the sheet in the sheet width direction, and a spectroscope that measures the spectral distribution of each of multiple patches for correcting color tones formed on the sheet and arranged in the sheet transport direction. The computational unit generates color tone correction data by performing computations based on the spectral distribution of each patch measured by the spectroscope, and the read values of the reference reflecting member obtained by the line sensor.

Image reading apparatus and method, and image forming apparatus

A capacitive load driving circuit including: a filter including an inductor to which an analog driving signal is input, and a capacitor with a fixed capacitance where one electrode is connected the inductor and other electrode grounded; a plurality of capacitive loads connected in parallel to the capacitor, and driven in accordance with the analog driving signal; a conversion section converting a load voltage to a digital signal; a signal processing section generating a predetermined signal for driving the capacitive load, deriving a signal that represents a magnitude of an electric current flowing to the capacitive load from the digital signal and a digital driving signal, subtracting the signal from the predetermined signal, and outputting the subtracted signal as the digital driving signal; and a switching section generating the analog driving signal by performing switching based on the digital driving signal, and outputting the analog driving signal.

Capacitive load driving circuit and liquid droplet jetting apparatus

There is provided a capacitive load driving circuit which applies a driving signal to a capacitive load. The driving circuit includes: an operational amplifier outputting a difference signal between signals from an inverting input terminal and a non-inverting input terminal, and setting a loop gain; a pulse width modulator pulse-width-modulating the difference signal outputted by the operational amplifier, and outputting resultant digital signal; a digital voltage amplifier amplifying a voltage of the digital signal; a first filter smoothing a digital signal from the digital voltage amplifier, and supplying a smoothed signal to the capacitive load as the driving signal; an impedance converting circuit converting an impedance of an output signal of the first filter; and a first feedback circuit feeding-back the driving signal, which is outputted from the first filter, to the inverting input terminal of the operational amplifier via the impedance converting circuit.

Capacitive load driving circuit and method, liquid droplet ejection device, and piezoelectric speaker driving device

The present invention provides an inspection device for a piezoelectric head. The piezoelectric head includes: a pressure chamber filled with liquid, a liquid supply channel that supplies the liquid to the pressure chamber, a nozzle at which droplets are jetted from the pressure chamber, and a piezoelectric element that applies pressure to the pressure chamber. The inspection device includes: a detection component that, when the piezoelectric element is driven on the basis of a predetermined detection signal, outputs a signal corresponding to behavior of an acoustic vibration system of the piezoelectric head; and a judgment component that, on the basis of the detection signal and the signal outputted by the detection component, judges for a cause of defective ejections at the piezoelectric head.

Piezoelectric head inspection device and droplet jetting device

A capacitive load driving circuit includes: a phase lead compensator, advancing a phase of an output signal of a filter; a series compensator, determining an error between a driving signal and an output signal of the phase lead compensator; a stabilization compensator, performing a derivative action on an output signal of the filter; a voltage comparison unit, comparing a differential voltage between a signal output from the series compensator and a signal output from the stabilization compensator, with a voltage of a predetermined triangular waveform, and outputting a pulse width modulation signal; a voltage amplification unit, amplifying the voltage of the pulse width modulation signal output, and supplying the amplified pulse width modulation signal to the input terminal of the filter; and plural capacitive loads each connected in parallel to the capacitor. A droplet ejection apparatus includes the capacitive load driving circuit.

Capacitive load driving circuit and droplet ejection apparatus

An ink non-ejection detecting circuit device for an inkjet recording apparatus is disclosed which comprises a bridge circuit including a piezoelectric head having a piezoelectric element, a first resistor connected in series to the piezoelectric head, a capacitor provided outside the piezoelectric head, and a second resistor connected in series to the capacitor. A differential voltage that appears between the piezoelectric head and the first resistor and between the capacitor and the second resistor is amplified, so that the acoustic-system admittance of the piezoelectric head can be detected with a high SN ratio.

Inkjet recording apparatus

A driving circuit of a droplet ejection head which, by supplying analog driving signals to driving elements, ejects droplets from nozzles which are provided in correspondence with the driving elements. The driving circuit includes a driving signal generation unit, a pulse modulation unit, a switching signal generation unit, an amplification unit and a frequency-setting unit. The driving signal generation unit selectively outputs a first and a second analog driving signal. The pulse modulation unit pulse-modulates the analog driving signal and outputs a digital signal. The switching signal generation unit generates a switching signal. The amplification unit amplifies the digital signal by switching in accordance with the switching signal, and supplies the amplified digital signal to the driving elements. The frequency-setting unit sets a switching frequency of the switching signal in accordance with a frequency selection signal, which corresponds to the analog driving signal.

Droplet ejection head driving circuit and method, and droplet ejection device

A capacitive load driving circuit which includes an operational amplifier, a pulse width modulator, a digital power amplifier, a first filter, a first feedback circuit and a second feedback circuit. The operational amplifier outputs a differential signal between a signal fed back to the inverting input terminal and an input signal inputted to the non-inverting input terminal. The pulse width modulator pulse width-modulates output from the operational amplifier and outputs a digital signal. The digital power amplifier amplifies power of the digital signal. The first filter smooths output of the digital power amplifier and inputs the smoothed signal to the capacitive load as the driving signal. The first feedback circuit feeds back the driving signal outputted from the first filter to the inverting input terminal of the operational amplifier. The second feedback circuit feeds back a signal outputted from the digital power amplifier, which signal includes a phase which is advanced relative to the driving signal, to the inverting input terminal of the operational amplifier.

Capacitive load driving circuit, droplet ejection device, droplet ejection unit and inkjet head driving circuit

In order to improve dullness of waveform of a drive signal having high slew rate necessary to jet ink droplets, which is caused by an influence of a low-pass filter formed by a resistance of a cable for connecting a power amplifier of an ink jet printer to piezo-electric heads of the printer, which are remote physically from the power amplifier, and a capacitance of the piezo-electric actuators, the ink jet printer includes intermediate circuit boardmounted on a carriage, control circuit boardhaving power amplifierand cable, wherein a negative feedback loop is provided from inputs of transfer gates mounted on intermediate circuit boardthrough wiringto power amplifiermounted on control circuit board

Drive circuit of ink jet head and driving method of ink jet head

A driving device for driving an ink jet printing head having N (N&equals;1, 2, 3, . . . ) nozzles includes a waveform generation circuit, three voltage amplification circuits, N multiplexers, and N current amplification circuits. The waveform generation circuit generates three waveforms for three driving signals VD , VD and VD corresponding to ink drop sizes &ldquo;large&rdquo;, &ldquo;middle&rdquo; and &ldquo;small&rdquo;. The three voltage amplification circuits amplify the voltage levels of the three waveforms respectively and thereby outputs the driving signals VD , VD and VD . Each of the N multiplexers corresponding to the N nozzles selectively transmits zero or one of the driving signals VD , VD and VD supplied from the voltage amplification circuits. Each of the N current amplification circuits corresponding to the N multiplexers amplifies the current level of the driving signal that has passed the corresponding multiplexer and thereby supplies the current-amplified driving signal to a corresponding piezoelectric actuator. The current amplification circuit is designed to have high input impedance, and the voltage amplification circuit is provided with an impedance conversion circuit and a feedback circuit for reducing its output impedance. By such composition of the driving device, precise and distortion-free driving signals can be supplied to the piezoelectric actuators and thereby high quality printing can be realized even when the frequency of the driving signal is high and even when a plurality of piezoelectric actuators of high load capacitance have to be driven.

Driving device and driving method for ink jet printing head

A driving circuit for ink jet head easily configured with inexpensive elements and which, without malfunctioning, generates desired driving waveform signals to drive piezoelectric actuators with a large capacitive load. The driving circuit for ink jet head is provided with a ROM which stores time information and current information for each diameter of ink jet droplets, waveform control circuits which read out the current information from the ROM according to the shape of the corresponding driving waveform signal and output that information as driving waveform data, waveform generating circuits which convert the driving waveform data into analog information and then perform integration operations on that data, to generate driving waveform signals, a data transmission circuit which selects one of the driving waveform signals according to the gradation information of the printing data and applies thus selected signal to the piezoelectric actuators, a data receiving circuit, and transfer gates.

Driving circuit for ink jet printing head

A carriage motor control device that uses speed determination means (3) for determining a set speed value (SN12) to be set on the basis of an aimed angle value (SN13A) indicative of an aimed rotation angle, an aimed speed value (SN13B) indicative of an aimed rotation speed and the rotation angle value, speed control means (4) for generating a speed control value (SN7) for making the rotation speed value closer to the set speed value on the basis of a difference between the rotation speed value and the set speed value, angle control means (5) for generating an angle control value (SN8) for making the rotation angle value closer to the aimed angle value on the basis of a difference between the aimed angle value and the rotation angle value, selection means (8) for selecting the speed control value as a motor drive control value when the rotation speed value is larger than a first speed value and selecting the angle control value as the motor drive control value when the rotation speed value is smaller than the first speed value and, drive pulse generation means (6) for generating a motor drive signal modulated according to a magnitude of the motor drive control value and for outputting the motor drive pulse signal as a forward motor drive signal or a reverse motor drive signal on the basis of the signal indicative of the direction of rotation.

Growing community of inventors

Kanagawa, Japan

Sunao Ishizaki