JPH03267959A - Recording density control system of laser recording device - Google Patents

Abstract

PURPOSE:To accurately set desired recording density by modulating the pulse width of recording data according to recording density information. CONSTITUTION:The system is equipped with a means which generates the recording density information SD showing the recording density and a recording density control means 15 when the recording density of the laser recording device equipped with a means 4 which generates a light emission driving signal according to recording data DT, generates laser light modulated with the light emission driving signal, and deflects the laser light by a deflection optical shape 3 to scan a photosensitive body 5. Then the recording density control means 15 modulates the pulse width of picture element data of the recording data DT in picture element units according to the recording density information SD and outputs the modulated data DT' as the light emission driving signal. Consequently, the recording density can be varied linearly over the entire control range, so desired recording density can easily and accurately be set.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a laser recording device used for recording recorded data of a personal computer or word processor, or facsimile image data, and particularly The present invention relates to a method for controlling the recording density of a recorded image.

(Prior Art) Generally, the exposure unit of this type of recording apparatus is, for example, a third
It is configured as shown in the figure. That is, when record data DT is input to the record scan control section 1, a light emission drive signal corresponding to the record data DT is outputted from the record scan control section 1, and is supplied to the laser beam generation section 2. This laser beam generating section 2 uses, for example, a laser diode as a laser emitting element, and after the laser diode emits light that is modulated by the above-mentioned light emission drive signal and reflected by a polygon mirror 3, the scanning direction is determined by an fθ lens 4. After correction, a horizontal line is scanned on the photosensitive drum 5 at a constant speed. At this time, the photosensitive drum 5 is rotated stepwise in synchronization with the scanning of one line, and the recording data is transferred onto the photosensitive drum 5 by the cooperation of the sub-scanning of the photosensitive drum 5 and the main scanning of the laser beam. An electrostatic latent image corresponding to DT is formed.

Incidentally, this type of apparatus generally has a function of controlling the recording density of an image, and conventionally, this recording density has been controlled by, for example, varying the output level of a laser beam. However, in such conventional methods, the variable range of the output level is limited by the light emitting output characteristics of the laser diode, so the control range of the density is generally narrow, and the recording density cannot be varied linearly, so it is difficult to achieve the desired level. It was difficult to set the recording density accurately.

(Issue 8 to be solved by the invention) As described above, the conventional recording density control method has the problem that the control range is narrow and it is difficult to obtain high control accuracy, and the present invention focuses on this point. It is an object of the present invention to provide a recording density control method that makes it unnecessary to vary the output level of a laser beam, thereby making it possible to set a wide control range and improve control accuracy.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention creates a light emission drive signal according to recorded data, and generates a laser beam modulated by this light emission drive signal. In a recording density control method of a laser recording apparatus that includes means for deflecting this laser light by a deflection optical system and scanning it on a photoreceptor, the recording density control method includes: a means for generating recording density information representing recording density; and a recording density control means. The recording density control means modulates the pulse width of the pixel data for each unit pixel of the recording data according to the recording density information, and outputs the modulated data as a light emission drive signal. This is what I did.

Further, in the present invention, the density control means includes a timer for measuring a time corresponding to the value of the recording density information for each unit pixel of the recording data, and the time output of the clocking means and the recording data are Another feature of the present invention is that it is configured to generate a light emission drive signal through logical processing.

(Function) As a result, according to the present invention, since the recording density is controlled by modulating the pulse width of recording data according to the recording density information, the recording density can be controlled independently of the light emission output characteristics of the laser light emitting element. Can be set. Therefore, the control range can be set widely, and the recording density can be varied linearly over the entire control range.
Desired recording density can be easily and accurately set.

In addition, by performing pulse width modulation using a clock means, it is possible to always accurately set the recording density without being affected by variations in circuit elements, such as when using an analog delay circuit. .

(Embodiment) FIG. 1 is a circuit block diagram showing the configuration of a recording density control circuit to which a recording density control method according to an embodiment of the present invention is applied.

This recording density control circuit includes a clock oscillator 11, a frequency divider 12, a differentiation circuit 13, a counter 14, and an output control circuit 15. First of all, the clock oscillator 11 generates a clock CLK having a frequency sufficiently higher than the bit frequency of the recording data DT. The frequency divider 12 is
Tarock CLK generated from the clock oscillator 11
is frequency-divided by N in synchronization with the bit frequency of the recording data DT, thereby outputting a frequency-divided signal AS corresponding to the bit frequency of the recording data DT. The differentiating circuit 13 differentiates the rising edge of the frequency-divided signal AS output from the frequency divider 12, thereby generating a clear signal BS synchronized with the start timing of each bit of the recording data DT. This clear signal BS is used to clear the count value of the counter 14 and the output of a D flip-flop circuit 16, which will be described later.

The counter 14 starts counting the clock CLK generated from the clock oscillator 11 every time the count value is cleared by the clear signal BS, and when the count value reaches the value specified by the recording density setting data SD. At this point, a carry signal C5 is output. Recording density setting data S
D is inputted by, for example, a key switch or digital switch (not shown) and stored in the RAM, and the counter 14 stores the data SD read out from this RAM.
is supplied.

The output control circuit 15 includes a D flip-flop circuit 16,
It is composed of an AND circuit 17. Every time the carry signal C8 is supplied from the counter 14, the D flip-flop circuit 16 generates a pulse signal DS which becomes H'' level during the period from that time until the clear signal BS is supplied.
Output.

This pulse signal DS is supplied to an AND circuit 17. The AND circuit 17 outputs the recording data DT and the pulse signal DS.
AND processing is performed, thereby outputting pulse width modulated recording data DT'.

Next, the operation of the recording density control circuit configured as described above will be explained with reference to FIG.

When the record data DT is input, the frequency divider circuit 12 generates a frequency divided signal AS synchronized with the record data DT.
In response to this frequency-divided signal AS, the differentiating circuit 13 generates a clear signal BS synchronized with the recording data DT. Then, the counter 14 starts counting the clock CLK from the time when the clear signal BS is generated. Further, the output of the D flip-flop circuit 16 of the output control circuit 15 is cleared to "L# level" by the clear signal BS.

Now, assume that in this state, a time T specified by the recording density setting data SD has elapsed. Then, at this point, the carry signal C is output from the counter 14 as shown in FIG.
8 is generated, and the output of the D flip-flop circuit 16 of the output control circuit 15 changes to the "H" level by this carry signal C8. The state of this "H level" is held until the next clear signal BS is generated. That is, the state of "H level" is maintained until the next clear signal BS is generated.
The pulse width of the H'' level pulse signal DS corresponds to the value specified by the recording density setting data SD.The pulse signal DS thus output is ANDed with the recording data DT by an AND circuit 17. As a result, recording data DT' whose pulse width is modulated according to the recording density is output.

This record data DT' is supplied to the laser beam generator 2 shown in FIG. 3, for example, and the laser beam generator 2 generates a laser beam whose pulse width is modulated according to the record data DT'. Ru. Then, this laser beam is deflected by a polygon mirror 3 and an fθ lens 4, respectively, and scanned onto a photosensitive drum 5. Therefore, if the latent image formed on the photosensitive drum 5 is developed in this way, recording of a density according to the pulse width of the laser beam, that is, the recording data DT' whose pulse width is set according to the recording density setting data SD. An image is obtained. In the example shown in FIG. 2, a recorded image whose recording density is slightly higher than medium is obtained.

In the circuit of this embodiment, if it is desired to further increase the recording density, the recording density setting data SD for setting the count time T of the counter 14 even shorter can be inputted and set in the counter 14.

In this way, the pulse width of the print data DT' output from the AND circuit 17 of the output control circuit 15 becomes wider, and as a result, the print density of the print image becomes even darker.

On the other hand, if you want to reduce the recording density, use the counter 14.
The recording density setting data SD for setting a longer count time T may be input and set in the counter 14. In this way, the pulse width of the recording data DT' output from the AND circuit 17 of the output control circuit 15 becomes narrower, and as a result, the recording density of the recorded image becomes thinner.

As described above, in this embodiment, the recording density is controlled by modulating the pulse width for each pixel of the recording data DT, so it is possible to control the recording density over a wide range compared to the case where the emission output level of the laser beam is varied. It becomes possible to control the recording density in a linear manner, thereby making it possible to obtain the desired recording density extremely easily and accurately. In addition, in the circuit of this embodiment, the pulse width is controlled using the counter 14, so the pulse width can be controlled without being affected by variations in circuit elements, etc., compared to the case where, for example, an analog delay circuit is used. It is possible to always set accurately without causing variations.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, for each pixel of the recording data DT,
Although the period T during which the signal level is at the "L" level is set according to the recording density setting data SD, it is also possible to directly set the period during which the signal level is at the "H" level using the recording density setting data SD. good.

In addition, the circuit configuration of the recording density control circuit, the configuration of the means for inputting and setting the recording density, etc. can be modified in various ways without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, the present invention includes means for generating recording density information representing recording density, recording density control means,
This recording density control means modulates the pulse width of the pixel data for each unit pixel of the recording data according to the recording density information, and outputs this modulated data as a light emission drive signal. be.

Therefore, according to the present invention, it is possible to eliminate the need to vary the power level of the laser beam, thereby providing a recording density control method that can set a wide control range and improve control accuracy.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing the configuration of a recording density control circuit to which a recording density control method according to an embodiment of the present invention is applied, FIG. 2 is a timing diagram used to explain the operation of the control circuit, and FIG. 3 is a timing chart used to explain the operation of the control circuit. It is a perspective view showing an example of composition of an exposure unit of a laser recording device. DESCRIPTION OF SYMBOLS 1... Recording scan control unit, 2... Laser beam generation unit, 3... Polygon mirror 4... fθ lens, 5...
...Photosensitive drum, 11...Clock oscillator, 12...
- Frequency division circuit, 13... Differentiation circuit, 14... Counter, 15... Output control circuit, 16... D flip-flop circuit, 17... AND circuit, DT... Recording data, SD ...recording density setting data, AS...divided signal, BS...clear signal, C8...carry signal, D
S...Pulse signal, DT'...Pulse width modulated recording data.

Claims (2)

[Claims] (1) A means for creating a light emission drive signal according to recorded data, generating a laser beam modulated by the light emission drive signal, deflecting the laser beam by a deflection optical system, and scanning it on a photoreceptor. A recording density control method for a laser recording apparatus according to the present invention, comprising: means for generating recording density information representing recording density; and for each unit pixel of the recording data, modulating the pulse width of the pixel data according to the recording density information; 1. A recording density control method for a laser recording apparatus, comprising a density control means for outputting the modulated data as a light emission drive signal. (2) The density control means has a timer for measuring a time corresponding to the value of the recording density information for each unit pixel of the recording data, and logically processes the clock output of the timer and the recording data. 2. A recording density control method for a laser recording apparatus according to claim 1, wherein a light emission drive signal is generated by performing the following steps.