JPH0666864B2 - Recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention is to change a dot interval (a dot interval means an interval between respective centers of dots) written on a recording medium. Recording device that can do

2. Related Art First, an electrophotographic recording apparatus using a cathode ray tube (hereinafter referred to as CRT) will be described.

FIG. 1 shows an outline of an electrophotographic apparatus using a CRT as an exposure apparatus.

For example, around the photosensitive drum 1 having a photosensitive surface formed of selenium or the like on the surface thereof, a strip electrode 2 for charging the photosensitive drum 1 with an electric charge, and the photosensitive drum 1 charged by the strip electrode 2 are provided. An exposure device 3 for exposing the electrostatic latent image to form an electrostatic latent image, a developing unit 4 for adsorbing toner to the electrostatic latent image to form a toner image, and a toner image formed on the photosensitive drum 1. To a copy sheet (the path of which is indicated by a dashed arrow), a separation pole 6 for separating the copy sheet from the photosensitive drum 1, and a surface of the photosensitive drum 1 after the transfer is completed. A cleaning unit 7 is provided for cleaning the.

The exposure device 3 described above horizontally scans the electron beam corresponding to the input image signal to form a bright and dark image of light on the fluorescent surface.
It is composed of a CRT 3a and a fiber plate 3c which is integrally provided on the front surface of the fluorescent surface of the CRT 3a and is composed of a plurality of optical fibers arranged in the main scanning direction (direction perpendicular to the plane of the drawing). The tips of the plurality of optical fibers forming the fiber plate 3c are set to face the central axis of the photosensitive drum 1.

The photo sensor 8 is a reflection type photo sensor that detects the reflection density of the patch pattern image for controlling the toner density by the toner formed on the photosensitive drum, and controls the toner replenishment based on the detection output of the photo sensor 8. The toner density of the toner image formed on the photosensitive drum 1 is automatically controlled.

A drive / amplification circuit 9 is connected to the CRT 3a, and the drive / amplification circuit 9 is connected to a control circuit 10 for controlling the entire recording apparatus.

Here, the operation for forming an electrostatic latent image on the photosensitive drum 1 will be described.

An electrostatic latent image is formed on the photosensitive drum 1 by irradiation of light. In this recording device, the electrostatic latent image is formed on the photosensitive drum 1 by the CRT 3a that emits light when the electron beam irradiates the fluorescent surface. Is formed.

When the photoconductor drum 1 rotates in the direction of the arrow and the electron beam of the CRT 3a is scanned many times in the direction in which the optical fiber 3c is provided, an electrostatic latent image is formed on the photoconductor drum 1. It becomes possible. A signal for scanning the electron beam of the CRT 3a is called a scan synchronization signal, and a sawtooth voltage as shown in FIG. 2 is applied to the deflection circuit 3b of the CRT 3a by this signal, and the electron beam reciprocates on the fluorescent surface. . When this voltage rises, the electron beam scans the fluorescent surface,
When the voltage drops, the electron beam returns to its original position.

Then, while the electron beam scans the fluorescent surface, CRT3a
The amount of electrons emitted from the electron gun is controlled, and during the scanning of the electron beam, a place where the electron beam irradiates the fluorescent surface and a place where the electron beam does not irradiate are created. It forms a latent image.

In order to obtain a desired image record or the like, it has to be confirmed which position of the fluorescent surface is irradiated with the electron beam. Irrespective of the irradiation position of the electron beam on the fluorescent surface, the desired electrostatic latent image is not formed on the photosensitive drum 1 even when the on / off control of the electrons emitted from the electron gun is performed.

Therefore, the time required for one scanning of the electron beam on the fluorescent surface is finely divided, and the frequency of the signal corresponding to this is made,
By counting the number of these frequencies, the irradiation position of the electron beam on the fluorescent surface at a certain time is confirmed,
The on / off control of the electrons emitted from the electron gun by the image signal is performed corresponding to the irradiation position.

A signal for synchronizing the irradiation position of the electron beam and the image signal is called an image synchronization signal. If the frequency of the image synchronization signal is increased, the irradiation position of the electron beam can be confirmed finely, and the on / off control of the electrons emitted from the electron gun is performed in accordance with this, so that high density and high resolution can be achieved. Recording is marked, but conversely, if the frequency is lowered, a recording with low resolution will be recorded. That is, the interval between dots on the copy paper in the traveling direction of the electron beam is determined by the frequency of the image synchronization signal.

Even in examining the difference in the use of the electrophotographic recording apparatus (whether high resolution recording is required or not) and the resolution of the electron beam exposure apparatus used in these apparatuses,
It is desirable that the interval between dots printed on the copy paper can be freely changed.

Normally, in a recording apparatus, the image synchronizing signal and the scanning synchronizing signal are not generated by separate oscillators in order to synchronize them, but the frequency of one signal is generated by one oscillator and the other is generated by dividing this frequency. The frequency of the signal is to be extracted. That is, the image synchronizing signal and the scanning synchronizing signal are taken out from one oscillator.

However, to adjust the dot spacing on the copy paper,
It is necessary to keep the frequency of the scanning synchronization signal constant and change only the frequency of the image synchronization signal. If you divide this by one oscillator and take out the image synchronization signal,
For example, when the frequency of the oscillator is 5MHz, the frequency obtained as the image synchronization signal is 5MHz, which is 2.5MHz,
It becomes 1.25MHz etc. The number of dots described by these image synchronization signals is 300 dots / inch at 5 MHz, 150 dots / inch at 2.5 MHz, and 75 dots at 1.25 MHz.
It becomes dots / inch. The dot spacing on the copy paper is
Since it is inversely proportional to the frequency of the image synchronizing signal, that is, the dot density (dots / inch) is proportional to the frequency of the image synchronizing signal. ), And the dot spacing at 5 MHz is 1, 2.
It becomes 2 at 5MHz and 4 at 1.25MHz,
Although I could adjust the dot spacing, I could only adjust the dot spacing roughly.

There is a limit to the adjustment of the dot interval if one oscillator takes out the image synchronizing signal and the scanning synchronizing signal and divides the frequency of the image synchronizing signals of various frequencies.

Therefore, in order to finely change the dot interval, as shown in FIG. 3, a large number of oscillators 11 having different frequencies must be prepared, and the frequency dividing circuit for obtaining the frequency of the scanning synchronization signal must also be provided. It had to be separately provided in order to synchronize with the image synchronization signal.

3. Object of the invention The present inventor has found that from the frequency obtained by one oscillator,
Even when extracting the image synchronization signal and the scanning synchronization signal, if there is a frequency converter that finely converts the frequency of the image synchronization signal, as described above, even if a large number of oscillators and frequency dividing circuits are not provided, the dot Thought that the interval of can be adjusted,
The present invention has been accomplished.

4. Structure of the Invention That is, the present invention is a recording apparatus using a cathode ray tube, an oscillator for obtaining a predetermined frequency signal, a frequency dividing circuit for frequency-dividing this frequency to obtain a scanning synchronization signal, and a division signal generation. And a phase-locked loop circuit for applying a division number input signal from the division signal generator to synchronize with the scanning synchronization signal and to output a first signal having a frequency corresponding to the division number input signal. , An image pattern generator that controls the timing of an image signal by using the output of this phase-locked loop circuit as an image synchronization signal, and a first signal that amplifies the output of this image pattern generator and outputs a second signal. An amplifier, a second amplifier that amplifies the scan synchronization signal and outputs a third signal, and a cathode that applies the third signal to scan an electron beam on a phosphor screen in a predetermined synchronization. By applying a deflection circuit in the tube and the second signal to the cathode in the cathode ray tube, an electrostatic latent image in the cathode ray tube capable of forming an electrostatic latent image on the photosensitive drum with a dot interval inversely proportional to the image synchronizing signal. The present invention relates to a recording apparatus comprising a fiber and being configured to control the interval between dots printed on a recording medium.

5. Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

FIG. 4 shows a drive circuit of a CRT 3a used in a recording apparatus, which incorporates a PLL circuit 16 capable of changing the frequency of an image synchronization signal into various frequencies.

To explain the circuit operation of this drive circuit, a predetermined frequency is obtained from the oscillator 11, and this frequency is divided by the frequency divider circuit 12 to extract the scanning synchronization signal and amplify it.
Amplified by 14, and applied to the deflection circuit 3b of the CRT 3a. By applying the scanning synchronization signal to the deflection circuit 3b, the electron beam scans the fluorescent surface in a predetermined synchronization.

Then, if the frequency obtained from the oscillator 11 is used as it is as an image synchronizing signal, the switch SW ₁ is connected to a as shown in the figure, and the output of the oscillator 11 is input to the image pattern generator 13. The timing of the image signal output from the image pattern generator 13 is controlled by this image synchronization signal, which is amplified by the amplifier 15 and applied to the cathode K of the CRT 3a.

By applying the scanning synchronization signal to the deflection circuit 3b of the CRT 3a, the electron beam scans the fluorescent surface, and the image synchronization signal generates an image signal corresponding to the irradiation position of the electron beam on the fluorescent surface.
It is applied to the cathode K of the CRT 3a, and the photosensitive drum 1 provided on the front surface of the optical fiber 3c is
An electrostatic latent image is formed by a dot pattern image having dot intervals that are inversely proportional to the frequency of the image synchronization signal.

Next, the case where the image synchronizing signal is converted in this circuit will be described.

When the frequency of the oscillator 11 is not used as it is as an image synchronizing signal, the switch SW ₁ is connected to b.

Then, the output of the frequency divider circuit is connected to the input of the PLL circuit.

As shown in FIG. 5, the internal configuration of the PLL circuit 16 includes a phase comparator 18, a low pass filter 19, a voltage controlled oscillator (VC
O) 20, and divider 21 and input terminal of divider 21
By changing the division number input signal added to A and B, P
The frequency of the output of the LL circuit 16 can be converted. For example, when the frequency input to the PLL circuit 16 is X, the PLL circuit 16
If the number of divisions of the input signal input to the frequency divider 21 is N, then the output frequency Y from the PLL circuit 16 is NX. The division number signal input to the frequency divider 21 can be formed by the division signal generator 17 including a counter and a flip-flop, and the division number can be easily changed by changing the number of the counter. .

That is, if the scanning synchronizing signal output from the frequency dividing circuit 12 is input to the PLL circuit 16 and the division number input signal is applied to the frequency divider 21 provided in the PLL circuit 16, the scanning synchronizing signal is synchronized with the scanning synchronizing signal. ,
Also, the frequency corresponding to the number of divisions input to the frequency divider 21 is PLL
It is output as the output of the circuit 16. Explaining in more detail with concrete numbers, for example, an oscillator with a frequency of 5 MHz is used.
If it is generated at 11, and the frequency is divided by 5000 by the frequency dividing circuit 12, a frequency of 1 KHz appears at the output of the frequency dividing circuit 12. 1K
If the frequency of Hz is applied to the PLL circuit 16 and the number of divisions of the input signal applied to the frequency divider 21 is 4000, 4 MHz will be output from the PLL circuit 16.
The output of the frequency is output. Set this frequency to switch SW ₁ b
If it is connected to the side and used as an image synchronization signal, if the dot interval noted when the image synchronization signal is 5 MHz is 1, it becomes 1.25 at 4 MHz.

The frequency output from the output of the PLL circuit 16 is, as described above,
By changing the number of divisions of the signal input to the frequency divider 21 and adding a frequency dividing circuit between the frequency dividing circuit 12 and the PLL circuit 16, the dot spacing can be adjusted freely. .

FIG. 6 shows a comparative example showing the difference in the timings of two types of image synchronization signals having different frequencies.

As is clear from the above description, the laser beam scanning is possible in the case of a recording device or a recording density test device in which the timing of the image signal applied to the image pattern generator is controlled by the image synchronization signal. The present invention can be applied to a recording device or the like according to the present invention.

6. Effect of the Invention In the conventional example, in order to adjust the interval of the dots recorded on the recording medium, when one oscillator is used, only coarse adjustment can be made.
In order to finely adjust the dot interval, it was necessary to prepare an oscillator and a frequency dividing circuit according to the dot interval. Therefore, it is necessary to separately prepare an oscillator and a frequency dividing circuit according to the use of the recording device or the performance of the recording means to be tested.

However, according to the present invention, it is possible to extract the image synchronizing signals of a plurality of frequencies by one oscillator, and the frequencies are not extracted by the frequency dividing circuit as in the conventional case but are performed by the PLL circuit. Therefore, frequencies that cannot be extracted conventionally can be used as the image synchronization signal.

For this reason, it becomes possible to finely control the interval of the dots printed on the recording medium as compared with the conventional one, and conventionally, in the recording device or the recording density test device of the recording means, various kinds of different frequencies depending on the intended use of the test object can be obtained. It was necessary to prepare an oscillator and a frequency dividing circuit associated therewith, but according to the present invention, one oscillator, one PLL circuit, and one frequency dividing circuit can suffice.

Further, by inputting the scanning synchronization signal to the PLL circuit and using the output as the image synchronization signal, the scanning synchronization signal and the image synchronization signal can be synchronized with a simple circuit configuration, and the irradiation of the electron beam on the phosphor screen is performed. An image signal corresponding to the position can be applied to the cathode in the cathode line to scan the phosphor screen with the electron beam in a predetermined synchronization.

Moreover, since the PLL circuit is directly controlled by the divided signal generator, it is possible to easily obtain the frequency according to the intended use of the test, especially in the test device for the recording density of the recording means.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a recording apparatus using a cathode ray tube, FIG. 2 is a waveform diagram of a voltage applied to a deflection circuit of the cathode ray tube, and FIG. 3 is a circuit for extracting a plurality of image synchronizing signals according to a conventional example. FIG. 4 is a circuit diagram for extracting a plurality of image synchronizing signals according to the present invention, FIG. 5 is a schematic diagram of the internal configuration of a PLL circuit, and FIG. 6 is a waveform of a scanning synchronizing signal, an image synchronizing signal and an image signal. Fig. In the reference numerals used in the drawings, 1 ... Photosensitive drum 3a ... Cathode ray tube 3b ... Deflection circuit 3c ... Optical fiber plate 11 ... Oscillator 12 ... Dividing circuit 13 ... Image pattern Generator 14,15 …… Amplifier 16 …… PLL circuit 17 …… Split signal generator 18 …… Phase comparator 19 …… Low-pass filter 20 …… VCO 21 …… A frequency divider.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H04N 1/04 Z 7251-5C 1/36 A 2109-5C

Claims (1)

[Claims] 1. A recording apparatus using a cathode ray tube, comprising: an oscillator for obtaining a predetermined frequency signal, a frequency dividing circuit for dividing this frequency to obtain a scanning synchronization signal, a division signal generator, and this division signal. A phase-locked loop circuit for applying a division number input signal from a generator and synchronizing with the scanning synchronization signal and outputting a first signal having a frequency corresponding to the division number input signal, and the phase-locked loop circuit An image pattern generator that controls the timing of the image signal by making the output of the image synchronization signal an image synchronization signal, a first amplifier that amplifies the output of the image pattern generator and outputs a second signal, and the scan synchronization A second amplifier that amplifies a signal and outputs a third signal, and a deflection circuit in a cathode ray tube that scans a fluorescent screen with an electron beam in a predetermined synchronization by applying the third signal. , An optical fiber in a cathode ray tube capable of forming an electrostatic latent image having a dot interval inversely proportional to the image synchronizing signal on the photosensitive drum by applying the second signal to the cathode in the cathode ray tube. A recording apparatus, characterized in that the interval of dots written on a recording medium is controlled.