JPH0624034A - Electrophotographic printing device - Google Patents

Abstract

PURPOSE:To make it possible to change a diameter of 1 record dot in an electrophotographic printing device wherein laser beam is scanned and optical writing is performed at every 1 record dot by using a laser diode direct modulation system. CONSTITUTION:A laser diode lighting pulse width of 1 record dot is divided into several kinds of pulse widths from a laser drive signal at a pulse width controller 12. One of them is selected by a selector 13 so as to supply to a laser diode drive section 14. In response to the signal, a laser diode 21 is turned on and off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic printer, and more particularly to an electrophotographic printer which performs optical writing for each recording dot by using a laser diode linear modulation system in which a laser beam is scanned.

[0002]

2. Description of the Related Art In a conventional electrophotographic printing apparatus of this type, as shown in FIG. 3, a laser diode 21 controls a pulse width of one recording dot, which is proportional to the resolution, for a collimator by turning the laser beam on and off. Via the lens 22, the polygon mirror 23, and the lens 24, the latent image intensity corresponding to the drive pulse width in FIG. 4 is obtained on the surface of the photosensitive drum 25 which is charged in advance, and this electrostatic latent image is formed. When developed with toner, the toner adheres to a portion of the latent image intensity which is equal to or higher than the threshold value S to obtain the toner development of the recording dot.

[0003]

In the electrophotographic printing apparatus for performing optical writing by scanning the above-mentioned conventional laser beam and controlling the laser diode lighting pulse width of one recording dot by using the laser diode direct modulation method. Since the laser diode lighting pulse width is fixed and set in advance at the factory, the pulse width cannot be changed by the user.For example, when it is used for barcode printing, it will be read due to the difference in performance of the barcode reader. It causes inconvenience such as being unable to perform.

[0004]

The electrophotographic printing apparatus according to the present invention is an electrophotographic printing apparatus which scans a laser beam and performs optical writing for each recording dot by using a laser diode direct modulation system. A laser diode lighting pulse width control means for dividing and generating a plurality of types of pulse widths from the laser diode lighting pulse width of one recording dot and selecting one of them to variably set the recording dot diameter is provided. It is characterized by

[0005]

The present invention will be described below with reference to the drawings.

FIG. 1 (a) is a block diagram showing an embodiment of the present invention, and FIG. 1 (b) is a classification diagram showing options of laser diode lighting pulse width in this embodiment. Figure 1
In (a), reference numeral 11 is a print control unit for converting print data transmitted from a higher-level device into a laser drive signal,
12 is a pulse width control unit for delay-controlling the pulse width of the laser drive signal from the print control unit 11, 13 is a selection unit for selecting the signal pulse width from the pulse width control unit 12,
Reference numeral 14 denotes a laser diode drive unit for turning on / off the laser diode 21 according to the signal pulse width from the selection unit 14, and reference numeral 21 denotes a laser diode.

As an operation example, a case where the pulse width of one recording dot expressed by pulse width modulation has four values will be described. The print data sent from the host device is printed by the print control unit 1
The laser drive signal is converted by 1 and the pulse for each recording dot is sequentially transmitted to the pulse width control unit 12. When this signal is received by the pulse width control unit 12, the original pulse width is set to 100% and is divided into patterns of pulse delay widths of 75%, 50% and 25%. In the selection unit 13,
As shown in FIG.
As shown in (b), "0" is 100% and "1" is 75%.
%, "2" is associated with 50%, and "3" is associated with 25%, and the selection unit 13 selects one of them and sends it to the laser diode drive unit 14. The laser diode drive unit 14 turns on the laser diode 21 according to the selection result.

In the present embodiment, since the recording dot diameter can be changed, it is possible to obtain a readable print result corresponding to the performance difference of the bar code reader at the time of bar code printing.

FIG. 2 is a block diagram of another embodiment of the present invention, and shows a case where an operating section 15 for externally instructing a selected value in the selecting section 13 in the embodiment of FIG. 1 is added. By providing the operation unit 15, the user can easily change the recording dot diameter and can read the barcode regardless of the performance difference of the barcode reader when printing the barcode.

[0010]

As described above, according to the present invention, 1
By dividing the laser diode lighting pulse width of the recording dot into several kinds of pulse widths and selecting one of them to provide a laser diode lighting pulse width control means for varying the recording dot diameter, Can be easily changed, and readable print results can be obtained regardless of the performance difference of the barcode reader.

[Brief description of drawings]

1A and 1B are a block diagram and a classification diagram of an embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional electrophotographic printing apparatus.

FIG. 4 is a pattern diagram for explaining a process of developing one recording dot in the present invention and the conventional apparatus.

[Explanation of symbols]

 11 Print Control Section 12 Pulse Width Control Section 13 Select Section 14 Laser Diode Drive Section 15 Operation Panel 21 Laser Diode 22, 24 Lens 23 Polygon Mirror 25 Photosensitive Drum

Claims (2)

[Claims] 1. An electrophotographic printing apparatus that scans a laser beam and performs optical writing for each recording dot by using a laser diode direct modulation method, and a plurality of types of pulses from the laser diode lighting pulse width of the one recording dot. An electrophotographic printing apparatus comprising a laser diode lighting pulse width control means for dividing and generating widths and selecting one of them to variably set a recording dot diameter. 2. The electrophotographic printing apparatus according to claim 1, further comprising operation means for performing an operation of selecting the recording dot diameter.