JP2001191585A - Electronic equipment, imaging device, copying machine and facsimile device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the supply of a clock signal whose frequency is diffused to a part of the circuit of electronic equipment and the supply of a clock signal whose frequency is stable to another part of the circuit, through a simple circuit layout and at a low manufacturing cost. SOLUTION: A clock signal CLK1 whose frequency is diffused is generated by a crystal oscillator 12 and a frequency diffuse oscillator 13 and the generated clock signal CLK1 is supplied to CPU 11. A counter 15 divides the frequency of the clock signal CLK1 to create a reference clock signal CLK2 based on the clock signal CLK1. In this case, the number of times of the created clock signals CLK2 counted by the counter 15, is counted in terms of the same number of clock pulses as the frequency diffusion period of the frequency diffuse oscillator 13. A PLL circuit 16 uses the reference clock signal CLK2 and generates a write clock signal CLK3 as a successive multiplication clock signal which is phasesynchronized with a scan detection signal, using the reference clock signal CLK2. A write signal generating park 17 generates a laser diode drive signal by synchronizing an image signal with the write clock signal CLK3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic apparatus, an image forming apparatus, a copying machine, and a facsimile machine.

[0002]

2. Description of the Related Art In recent years, as means for suppressing EMI noise, a frequency spread oscillator (Spectrum Spread Clock Genera) has been used.
tor) is used. Frequency spreading refers to periodically varying the frequency of a clock signal having a fixed frequency obtained from an oscillation element such as a quartz oscillator, with a predetermined profile as illustrated in FIG. By spreading the frequency with a spread spectrum oscillator,
By dispersing the frequency at which EMI noise occurs, the occurrence of EMI noise can be suppressed.

[0003]

In an electrophotographic image forming apparatus used for a laser printer, a digital copying machine, a facsimile machine, or the like, when the above-described frequency spreading is performed, the periodic fluctuation of the frequency is caused. There are allowed circuit parts and unacceptable circuit parts. In other words, the CPU for controlling the apparatus and the I / F for connecting an external device such as a personal computer have no problem due to frequency spreading of the clock signal to be used. In the writing unit for writing,
Periodic fluctuations in the frequency of the write signal may cause image abnormalities (banding, interference fringes, etc.), and a write signal of the write unit requires a clock signal without frequency fluctuation.

To this end, separate oscillation circuits are prepared for the CPU for controlling the device and for the write signal,
It is possible to use a frequency-spread oscillator for writing, and to use a signal from an oscillation circuit that does not fluctuate in frequency for the write signal, but this would require two oscillation circuits. There is a problem that the configuration becomes complicated and the manufacturing cost is raised.

An object of the present invention is to simply supply a clock signal having a spread frequency to one part of a circuit of an electronic device and supply a clock signal having a stable frequency to another part of the circuit. The circuit configuration is to be realized at a low manufacturing cost.

Another object of the present invention is to increase the degree of freedom of the frequency of the oscillation element in the above case.

Another object of the present invention is to realize a clock signal having a stable frequency with a relatively simple circuit configuration in the above case.

Another object of the present invention is to reduce the size of the device and the manufacturing cost in the above case.

[0009]

According to a first aspect of the present invention, there is provided a frequency spread oscillator for generating a first clock signal which is frequency-spread based on a clock signal output from an oscillation element and having a fixed frequency; A clock signal generation circuit that counts a predetermined number of pulses of the first clock signal by a counter to generate a second clock signal; a first circuit that operates using the first clock signal; A second circuit that operates using two clock signals, wherein the counter has the predetermined number equal to the frequency spreading period of the frequency spreader.

Therefore, it is possible to supply a clock signal having a frequency spread to the first circuit and to supply a clock signal having a stable frequency to the second circuit by using one oscillation element. In addition, the circuit configuration of the electronic device can be simplified, and the manufacturing cost can be reduced.

According to a second aspect of the present invention, in the electronic device of the first aspect, the clock signal generation circuit replaces the predetermined number with the same value as the frequency spreading period of the frequency spreader. Therefore, it is an integral multiple of the frequency spreading period.

Therefore, it is possible to increase the degree of freedom in the frequency of the oscillation element and the degree of freedom in selecting a constant when a PLL circuit is used for the clock signal generation circuit.

According to a third aspect of the present invention, in the electronic device according to the first or second aspect, the clock signal generation circuit uses the output signal of the counter to synchronize with the operation of the second circuit. And a PLL circuit for generating the second clock signal as a clock signal synchronized with the signal.

Therefore, the second clock signal can be generated as a clock signal that is phase-synchronized with the synchronization signal related to the operation of the second circuit.

According to a fourth aspect of the present invention, in the electronic device according to any one of the first to third aspects, the frequency spread oscillator and the clock signal generation circuit are mounted on a single integrated circuit. I have.

Therefore, the size of the apparatus can be reduced and the manufacturing cost can be reduced.

According to a fifth aspect of the present invention, there is provided a photoreceptor, an optical writing device for optically writing an electrostatic latent image on the photoreceptor by a predetermined light source, and the second circuit, wherein the second circuit is based on an image signal. A driving signal generation unit for generating a signal for driving the light source, and a C which controls the apparatus, the driving circuit being a first circuit.
A scanning detection signal, which is a synchronization signal when the optical writing device performs exposure scanning of the photoconductor, as a synchronization signal related to the operation of the second circuit, and an image based on the image signal. The image forming apparatus as an electronic apparatus according to claim 1, wherein the image forming apparatus forms an image on a sheet by an electrophotographic method.

Therefore, the same operation and effect as the invention according to any one of claims 1 to 4 can be realized in an electrophotographic image forming apparatus.

According to a sixth aspect of the present invention, there is provided a copying machine including an image reading apparatus for reading an image of a document and an image forming apparatus for forming an image of the read image. .

Therefore, the same operation and effect as the invention described in claim 5 can be realized in the copying machine.

According to a seventh aspect of the present invention, there is provided an image reading apparatus for reading an image of a document, a transmitting / receiving apparatus for transmitting image data of the read image and receiving image data from the outside, and a receiving / receiving apparatus for receiving the image data. An image forming apparatus according to claim 5, wherein the image forming apparatus forms an image based on the obtained image data.
Is a facsimile machine provided with:

Therefore, the same operation and effect as the invention described in claim 5 can be realized in the facsimile apparatus.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment of the Invention] One embodiment of the present invention will be described as a first embodiment of the present invention.

FIG. 1 is a conceptual diagram showing a schematic configuration around a photoreceptor of an image forming apparatus 1 according to a first embodiment of the present invention. The image forming apparatus 1 is an example of the electronic device of the present invention.

As shown in FIG. 1, the image forming apparatus 1 includes a writing unit 2 which is an optical writing device. The writing unit 2 includes a laser output unit 3, an imaging lens 4 and a mirror 5. Inside the laser output unit 3, a laser diode serving as a laser light source and a multi-unit which rotates at a high speed and a constant speed by a predetermined motor are provided. A square mirror (polygon mirror) is provided. The laser beam output from the writing unit 2 is applied to the photoconductor 6 to form an electrostatic latent image.

The procedure for developing the electrostatic latent image formed on the photoreceptor 6 to form an image on transfer paper is roughly as follows. First, the transfer paper is transported to a position where it comes into contact with the photoconductor 6. Then, an image signal output from a controller (not shown) is written on the photoconductor 6 by the laser from the writing unit 2 to form an electrostatic latent image, and the electrostatic latent image passes through the developing unit 7 which is a developing unit. As a result, the electrostatic latent image is developed to form a toner image. And
While the transfer paper is being conveyed by the conveyance belt 8 at the same speed as the rotation of the photoconductor 6, the toner image on the photoconductor 6 is transferred by a transfer unit (not shown). Thereafter, the image is fixed by the fixing unit 9. Around the photoconductor 6, a charger for charging the photoconductor 6, a cleaning device for removing residual toner on the photoconductor 6, a static eliminator for removing the charge of the photoconductor 6, and the like are arranged, although not shown. ing.

FIG. 2 is a block diagram showing the electrical connection of the control system of the writing unit 2. As shown in FIG. 2, a crystal oscillator 12 as an oscillation element is connected to a frequency spread oscillator (SSCG) 13 to generate a clock signal CLK1 as a first clock signal whose frequency is spread.
C which is a first circuit for centrally controlling the image forming apparatus 1
The PU 11 outputs the frequency-spread clock signal CLK.
1 operates. Writing ASIC (Application Sp
ecified IC) 14 is an integrated circuit that generates a laser diode drive signal for driving a laser diode (LD) inside the laser output unit 3 by synchronizing an image signal output from a controller (not shown) with a write signal. is there.

The write ASIC 14 is supplied with a clock signal CLK1 whose frequency has been spread. Write AS
The counter 15 of the IC 14 outputs the clock signal CLK1
Is divided by a predetermined frequency division ratio, so that the clock signal C
A reference clock signal CLK2 is created from LK1. At this time, the count number of the counter 15 is
Counting is performed with the same number of clocks as the frequency spreading period of 3.
For example, in the example of the profile of FIG. 3, the frequency spreading cycle is performed at 240 clocks (the clock is 25 MHz).
Since it is z, one clock is 40 ns. 40ns × 240
Number = 9.60 μs cycle). Therefore, the frequency division ratio of the counter 15 is set to 240 clocks. Then, the reference clock signal CLK2 having a fixed frequency can be created regardless of whether the frequency of the clock signal is spread or the frequency is divided at any timing. Note that the count number of the counter 15 may be counted by an integer multiple of the same clock number as the frequency spread cycle of the frequency spread oscillator 13.

The PLL circuit 16 of the write ASIC 14 uses the reference clock signal CLK2 to write a write clock signal, which is a multiplied clock signal that is phase-synchronized with a scan detection signal that is a synchronization signal when the laser output unit 3 scans the photosensitive member 6. CLK3 is generated. The write clock signal CLK3 is a second clock signal having a longer cycle than the clock signal CLK1. The counter 15 and the PLL circuit 16 implement a clock signal generation circuit. The write signal generator 17 of the write ASIC 14 generates a laser diode drive signal by synchronizing the image signal from the controller with the write signal. The write signal generator 17 implements a second circuit and a drive signal generator.

According to the image forming apparatus 1 described above, C
Since it is possible to supply the PU 11 with the frequency-spread clock signal CLK1 and supply the write signal generation unit 17 with the write clock signal CLK3 having a stable frequency by using one crystal oscillator 12, the circuit By simplifying the configuration, the manufacturing cost can be reduced.

When the count number of the counter 15 is counted by an integer multiple of the same clock number as the frequency spread cycle of the frequency spread oscillator 13, the crystal oscillator 12
And the degree of freedom in selecting the constant of the PLL circuit 16 can be increased.

Further, by using the PLL circuit 16, the clock signal C is used as a signal synchronized with the scanning detection signal.
LK3 can be generated.

As shown in FIG. 4, the frequency spread oscillator 13 may be integrated inside the write ASIC 14. This makes it possible to reduce the size of the device and reduce the manufacturing cost.

FIG. 5 is a block diagram showing an electrical connection of a control system of the writing unit, which is a comparative example of the circuits of FIGS. 2 and 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The circuit shown in FIG. 5 differs from the circuits shown in FIGS. 2 and 4 in the following points. That is, as shown in FIG. 5, the frequency spread oscillator 13 is not used, and a clock signal CLK1 that is not frequency-spread is generated by the crystal oscillator 12 and the oscillator 18 built in the CPU 11, and the CPU 11 is controlled by the clock signal CLK1. It operates to generate the reference clock signal CLK2.

In the circuit example of FIG. 5, a frequency spread oscillator is not used as compared with the case of the image forming apparatus 1, so that
It can be seen that EMI noise cannot be suppressed.

FIG. 6 is a block diagram showing an electrical connection of the control system of the writing unit, which is a comparative example of the circuits of FIGS. 2 and 4 are denoted by the same reference numerals, and detailed description thereof will be omitted. The circuit shown in FIG. 6 differs from the circuits shown in FIGS. 2 and 4 in the following points. That is, as shown in FIG. 6, a crystal oscillator 19 and an oscillator 20 to which the crystal oscillator 19 is connected are provided separately from the crystal oscillator 12 and the frequency diffusion oscillator 13, and the frequency fixed generated by the oscillator 20 is provided. Is input to the counter 15 in place of the clock signal Clk1, and the counter 15 and the PLL circuit 16 generate the clock signals CLK2 and CLK3. The write ASIC 14 is supplied with the frequency-spread clock signal CLK1, and the write clock signal CL is supplied.
The portion other than the portion related to the generation of K3 can be operated with the spread clock signal Clk1.

In the circuit example of FIG. 6, the write clock signal CLK3 can be a clock signal having a stable frequency, but compared with the case of the image forming apparatus 1,
It can be seen that two crystal oscillators are required in total, which increases the manufacturing cost of the device.

[Second Embodiment of the Invention] Another embodiment of the present invention will be described as a second embodiment of the present invention.

FIG. 7 is a block diagram showing a schematic configuration of a copying machine 21 according to the second embodiment of the present invention. The copying machine 21 includes an image reading device 22 that reads an image of a document,
The image forming apparatus 1 according to the first embodiment of the present invention that forms an image of the read image. Image reading device 2
Reference numeral 2 denotes, for example, a flat bed type image scanner, the detailed configuration of which is well known, and a detailed description thereof will be omitted.

According to the copying machine 21, the same operations and effects as those of the image forming apparatus 1 according to the first embodiment of the present invention can be obtained.

[Third Embodiment of the Invention] Another embodiment of the present invention will be described as a third embodiment of the present invention.

FIG. 8 is a block diagram showing a schematic configuration of a facsimile apparatus 31 according to the third embodiment of the present invention. The facsimile apparatus 31 includes an image reading apparatus 32 that reads an image of a document, and a transmitting / receiving apparatus that transmits image data of the read image and receives image data from an external facsimile apparatus via a telephone line or the like. 33, and the image forming apparatus 1 according to the first embodiment of the invention for forming an image based on the received image data. Since the configurations of the image reading device 32 and the transmission / reception device 33 are well known, detailed description will be omitted.

According to the facsimile apparatus 31, the same operations and effects as those of the image forming apparatus 1 according to the first embodiment of the present invention can be obtained.

In the above description, the present invention is applied to each of the image forming apparatus 1, the copying machine 21, and the facsimile apparatus 31, but the present invention is not limited to this. Needless to say. The present invention
CPU that is a part of the circuit in various electronic devices
For example, a clock signal whose frequency is spread can be used. However, the present invention can be applied to a case where a clock signal having a stable frequency is used for another part of the circuit.

[0045]

According to the first aspect of the present invention, the first circuit is supplied with a first clock signal whose frequency is spread, and the second circuit is supplied with the second clock signal.
It is possible to supply the first clock signal having a stable frequency to the circuit by using one oscillation element, so that the circuit configuration of the electronic device can be simplified and the manufacturing cost can be reduced. .

According to a second aspect of the present invention, in the electronic apparatus according to the first aspect, the degree of freedom of the frequency of the oscillation element and the degree of freedom in selecting a constant when a PLL circuit is used for the clock signal generation circuit are increased. Can be done.

According to a third aspect of the present invention, in the electronic device according to the first or second aspect, the second clock signal can be generated with a relatively simple circuit configuration using a counter and a PLL circuit.

According to a fourth aspect of the present invention, in the electronic device according to any one of the first to third aspects, the second clock signal is phase-synchronized with a synchronization signal related to the operation of the second circuit. A clock signal can be generated.

According to the fifth aspect of the invention, the same operation and effect as those of the first aspect of the invention can be realized in an electrophotographic image forming apparatus.

The invention described in claim 6 can realize the same operation and effect as the invention described in claim 5 in a copying machine.

According to the invention described in claim 7, the same operation and effect as the invention described in claim 5 can be realized in a facsimile apparatus.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a schematic configuration around a photoconductor of an image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is a block diagram illustrating an electrical connection of a control system of a writing unit of the image forming apparatus.

FIG. 3 is a graph showing an example of a profile of a periodic change in frequency by a spread spectrum oscillator.

FIG. 4 is a block diagram showing another example of the control system.

FIG. 5 is a block diagram showing a circuit as a comparative example with respect to the circuits of FIGS. 2 and 4;

FIG. 6 is a block diagram showing a circuit as a comparative example with respect to the circuits of FIGS. 2 and 4;

FIG. 7 is a block diagram showing a schematic configuration of a copying machine according to Embodiment 1 of the present invention;

FIG. 8 is a block diagram showing a schematic configuration of a facsimile apparatus according to the first embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus, electronic equipment 2 Optical writing device 6 Photoconductor 11 CPU, 1st circuit 12 Oscillation element 13 Frequency spreading circuit 14 Integrated circuit 15 Counter, clock signal generation circuit 16 PLL circuit, clock signal generation circuit 17 Drive signal generation Unit, Second Circuit 21 Copying Machine 22 Image Reading Device 31 Facsimile Device 32 Image Reading Device 33 Transmission / Reception Device

Claims (7)

[Claims] A frequency-spread oscillator that generates a first clock signal that is frequency-spread based on a clock signal output from an oscillation element and has a fixed frequency; and a counter that counts the number of pulses of the first clock signal by a counter. A clock signal generation circuit that counts by minute to generate a second clock signal; a first circuit that operates using the first clock signal; and a second circuit that operates using the second clock signal An electronic device comprising: the counter having the predetermined number as the same value as the frequency spreading period of the frequency spreader. 2. The clock signal generation circuit according to claim 1, wherein the predetermined number is set to an integral multiple of the frequency spread cycle instead of being set to the same value as the frequency spread cycle of the frequency spreader. Electronics. 3. The clock signal generation circuit as a clock signal phase-synchronized with a synchronization signal related to the operation of the second circuit using an output signal of the counter.
The electronic device according to claim 1, further comprising a PLL circuit that generates the clock signal. 4. The electronic device according to claim 1, wherein the frequency spread oscillator and the clock signal generation circuit are mounted on a single integrated circuit. 5. A photoconductor, an optical writing device for optically writing an electrostatic latent image on the photoconductor by a predetermined light source, and the second circuit, for driving the light source based on an image signal A driving signal generating unit for generating a signal of the first circuit; and a CPU which is the first circuit and controls the present device. The optical writing device is a photoconductor as a synchronization signal related to the operation of the second circuit. The electronic device according to any one of claims 1 to 4, wherein a scan detection signal that is a synchronization signal when exposing and scanning the image is used, and an image based on the image signal is formed on a sheet by an electrophotographic method. An image forming apparatus that is a device. 6. A copying machine comprising: an image reading device that reads an image of a document; and the image forming device according to claim 5, which forms an image of the read image. 7. An image reading device for reading an image of a document, a transmitting / receiving device for transmitting image data of the read image and receiving image data from the outside, and an image reading device based on the image data received by the transmitting / receiving device. A facsimile apparatus comprising: the image forming apparatus according to claim 5 for performing formation.