JPH04290761A - Laser image recording device - Google Patents

Abstract

PURPOSE:To prevent occurrence of irregularity on starting points of printing even in the case where printing density or resolution is changed in the middle of the printing by a method wherein the sum of printing driving current and bias current from a printing laser control circuit and from a reversal amplifier is made constant when setting of printing density is changed. CONSTITUTION:A printing laser control circuit LZ which amplifies, with a specified positive magnification, a printing density signal that changes the printing density for a laser image recording device, and a reversal amplifier AM which amplifies, with a negative magnification contrary to the positive magnification of the printing laser control circuit LZ, the printing density signal are provided. The sum of printing driving current I1 and bias current I2 from the printing laser control circuit LZ and from the reversal amplifier AM are made constant with a BD detecting section even in the case where setting of the printing density is changed, then the current made so constant is supplied to a laser beam emitter 12. Thereby the intensity of the laser beam for detecting a reference point for starting of the printing can be made constant even though the printing density is changed in the middle of the printing, and the starting points on the left end of paper will not become irregular.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a laser printer device,
This is a new laser image recording system that is related to the control method of the laser writing position when scanning a laser beam with a laser beam optical system to obtain image output in a copying machine, and specifically prevents the writing position from shifting when changing print density or resolution. Regarding equipment.

0002

2. Description of the Related Art In laser printers, the timing of the write position is usually based on a signal obtained by receiving a laser beam with a write position detector installed in front of the write position.

FIG. 4 shows a configuration diagram of an optical section 10 of a laser printer device. In the figure, 11 is a laser beam, 12 is a laser emitter, 13 is a polygon mirror, 14 is an fθ lens,
15 is a photoreceptor, 16 is a reflecting mirror, 17 is a writing position detector (hereinafter abbreviated as BD detector), 18 is a print medium (hereinafter abbreviated as paper), P is a writing reference point, and P' is a writing start position on the paper. shows.

The polygon mirror 13 reflects the laser beam 11 emitted from the laser emitter 12 while rotating, and reflects fθ.
It passes through the lens 14. The photoreceptor 15 is then scanned at a constant speed. Reflector 16 is polygon mirror 1
It is placed on the line between the reflection point No. 3 and the writing reference point P. The laser beam 11 is reflected by a reflecting mirror 16 and enters a BD detector 17 . A writing reference point P is determined by this incident light. A position moved by a predetermined distance to the left from the write reference point P, that is, a predetermined time after the detection of the write reference point P, is the write start position P' on the paper. The writing start position P' is the actual writing start position of the paper 18.

[0005] To detect the write start position, analog information is digitized by the BD detector 17, as shown in the explanatory diagram of the BD detection signal in FIG. W1 indicates the input waveform of the BD detector when the laser power is strong, W2 indicates the input waveform of the BD detector when the laser power is weak, and 19 indicates a predetermined slice level. The BD detector 17 receives the laser beam 1 shown in FIG. 5(A).
1 input analog waveform is converted into a digital signal at a predetermined slice level 19 as shown in FIG. 5(B) and output. W11 is the output waveform when the laser power is strong, W22
is the output waveform of the BD detector when the laser power is weak. This digitized signal is used as the writing start position. The BD detection signal detected by the BD detector at the writing reference point P is notified to a control unit (not shown), and the control unit creates printing data after a predetermined time from the rising timing of the BD detection signal, and outputs it as a printing signal. Outputting and writing print data.

[0006] When changing the intensity of the laser power, it is time to change the print density and print pattern resolution of the laser printer device, and when changing it, a print density adjustment dial (not shown) must be manually operated. As a result, the power of the laser beam 11 is increased or decreased to change the print density. When changing the resolution of the print pattern, manually operate a resolution adjustment dial (not shown) to increase or decrease the power of the laser beam 11 to change the diameter of the laser beam and adjust the diameter of the dots forming the print pattern. changing size.

[0007]

[Problem to be Solved by the Invention] As described above, when the strength of the laser beam is changed by operating the print density adjustment and resolution dials during printing, the laser beam 11 is digitized at a predetermined slice level 19. Figure 5 to the output signal
As shown in (B), a difference of Δt occurs in the timing. After a predetermined period of time from the rise of the digitized output signal, the print data is written to the write start position P'. A problem has arisen in which variations ΔL occur in the writing start position from the left end. Variation Δ
The distance L corresponds to the distance between the timing time difference Δt and the BD detection signal.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser image recording apparatus that does not cause variations in the writing start position even when a dial for changing print density and resolution is operated during a printing operation.

[0009]

[Means for Solving the Problems] In order to detect the writing start position according to the invention of claim 1, in order to achieve the above-mentioned object, as shown in the laser control circuit diagram A of FIG. A laser image recording device having a print density signal for controlling a print density signal and a print signal for controlling a bias current I2 and a BD timing signal for controlling a bias current I2, wherein the print density signal for changing the print density is set to a normal magnification of a predetermined value. A printing laser control circuit LZ that amplifies the printing density signal and an inverting amplifier AM that amplifies the printing density signal to a negative magnification that has a correlation opposite to the positive magnification of the printing laser control circuit LZ are provided, so that when the printing density setting is changed, Also, in the BD detection unit BDZ, the printing drive current I from the printing laser control circuit LZ and the inverting amplifier AM
1 and bias current I2 is kept constant and supplied to the laser emitter 12.

As shown in the laser control circuit diagram B of FIG. 7, the detection of the writing start position according to the invention of claim 2 is performed by using a laser emitter 12 that emits light according to an input signal, a print signal that forms an image, BD for detecting the writing start position of the print signal
The laser image recording device has a timing signal, a constant value output unit 27 that sends a constant laser current to the laser emitter 12, and a resolution signal and a density signal to set printing density and output any laser output. an output control section 26 that sends out a value, the constant value output section 27, and the output control section 2
6 and a selection section 28 that selects 6 and 6 based on the BD timing signal.

[0011]

[Operation] According to the configuration of the first aspect of the present invention, a printing laser control circuit and a printing density that amplify a printing density signal to a predetermined value even if the dial for changing the printing density is manually operated during printing operation, and the printing density. An inverting amplifier amplifies the signal to a negative magnification that has a correlation opposite to the positive magnification of the printing laser control circuit, so that the sum of the printing drive current and the bias current becomes constant, and the laser emitter current becomes constant. For this reason, no error occurs in the writing start position.

According to the second claim, when outputting a printing part other than the BD detection part of the print signal, the selection part selects the print density value and resolution value set by the print density adjustment dial and the resolution adjustment dial (not shown). It emits light with the intensity of the laser light as instructed. Further, when the print signal is output from the BD detection section, the laser beam is emitted with the intensity specified by the selection section at the constant value output section. Therefore, the light reception level of the detection signal at the writing start position at the left end of the paper can be improved.

[0013]

[Examples] The present invention will be explained below using examples. In order to make the explanation of the operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and their repeated explanation will be omitted.

Laser control circuit diagram A in FIG. 1 is a diagram showing the configuration of claim 1 of the present invention, and in the figure, the PR terminal is an input terminal for a print signal and is connected to a control section (not shown). N.D.
The terminal is an input terminal for a print density signal and is connected to a density adjustment dial (not shown) for controlling print density. LZ is a laser control circuit for printing, which amplifies the printing density signal by, for example, M times. SW1 is a power transistor that controls the printing drive current I1 based on the printing density signal and the printing signal. A.M.
For example, the inverting amplifier inverts the print density signal and amplifies it M times (minus M times). The BD terminal is an input terminal for a BD timing signal, and is connected to a control section (not shown), and is used for detecting a BD detection signal with a BD detector. The power transistor SW2 controls the bias current I2 based on the print density signal inverted and amplified by the inverting amplifier AM and the BD timing signal.

The laser emitter 12 emits light at the laser emitter current I3, and the laser emitter current I3 is equal to I3.
=I1+I2. The above print signal and BD timing are shown in FIG. 3(A). As shown in input signal timing chart A, the BD detection section BDZ is for the BD detector, and both the print signal and the BD timing signal are present. The print portion PRZ is a print data portion of a print signal.

In such a configuration, the current change diagram of the laser emitter in FIG. 2 shows the state when the print density signal is changed while the BD detection section BDZ is in the ON state. The laser emitter current I3 flowing through the laser emitter 12 is turned on with both power transistors W1 and W2 turned on, and the printing drive current I1 and bias current I2 are M times the inverse of each other, so the printing drive current I1 is a print density signal. The printing drive current I2 decreases inversely proportional to the printing density signal. Therefore, the timing chart A of the input signal in Figure 3 (A)
As shown in the figure, I3=I1+I2, and I3 is always constant. Also, in the printing section, only the power transistor SW1 is turned off.
In the N state, the laser emitter current I3 changes in intensity as specified by the print density changing dial to change the print density.

Next, an embodiment according to claim 2 will be explained. The laser control circuit diagram B in FIG. 7 shows the circuit configuration. 26
The output control unit outputs the output from the laser emitter 1 based on the sum of the resolution signal input from a dial for adjusting resolution (not shown) and the print density signal from a dial for adjusting print density (not shown).
You can set the output value to 2. The constant value output section 27 is composed of a multi-bit dip switch or memory, and the output to the laser emitter 12 is always set to a predetermined value. A selection section 28 selects either the output value of the constant value output section 27 or the output value of the output control section 26 based on the BD timing signal, and outputs the selected value to the laser emission section 20. 20 is a laser emitting unit, which operates an inverter 21 that inverts the polarity of the print signal, a laser emitter 12, an output current control transistor 22 that controls the current value flowing through the laser emitter 12, and an output current control transistor 22. For this purpose, it is composed of an amplifier 23 that amplifies the output signal from the selection section 28 and a light emission control transistor 25 that controls the laser emitter 12.

The operation of the above configuration will be explained with reference to the input signal timing chart A in FIG. 3 and the input signal timing chart B in FIG. 8. Selection section 2
8 selects the BD detection section BDZ of the BD timing signal and the printing section PRZ other than the BD detection section BDZ as follows. BD detection section BDZ of BD timing signal
In the range of , the output value of the constant value output section 27 is
0 to the amplifier 23. Then, the signal is amplified to a predetermined value by the amplifier 23 and applied to the output current control transistor 22. In the applied state, the polarity of the print signal is reversed by the inverter 21 and applied to the light emission control transistor 25, and a current I4 corresponding to the set value of the constant value output section 27 flows to the laser emitter 12 to output laser light. The current I4 does not change unless the settings of the dip switch or memory of the constant value sending section 27 are changed.

The BD detection signal other than the BD detection section BDZ, that is, the printing section PRZ outputs an output value set by the resolution signal and the density signal to the amplifier 23 of the laser emission section 20. The output current is then amplified to a predetermined value by the amplifier 23 and applied to the output current control transistor 22. In the applied state, the polarity of the print signal is reversed by the inverter 21 and applied to the light emission control transistor 25, and the output control unit 26 supplies a current I5 corresponding to the set value set by the resolution signal and the density signal to the laser emitter 12. outputs a laser beam. The current I5 changes each time by operating dials for resolution adjustment and print density adjustment (not shown), and changes in accordance with the dials.

[0020]

[Effects of the Invention] According to the present invention, even if the dial that changes the print density is changed during the printing operation, the intensity of the laser light when detecting the writing reference point is always constant, causing variations in the writing start position at the left edge of the paper. I won't let you. For this reason, printing quality can be improved.

[Brief explanation of the drawing]

FIG. 1 is a laser control circuit diagram A.

FIG. 2 is a current change diagram of a laser emitter.

FIG. 3 is a timing chart A of input signals.

FIG. 4 is a configuration diagram of the optical section.

FIG. 5 is an explanatory diagram of a BD detection signal.

FIG. 6 is an example of printed content.

FIG. 7 is a laser control circuit diagram B.

FIG. 8 is a timing chart B of input signals.

[Explanation of symbols]

10 Optical section 11 Laser beam 12 Laser emitter 13 Polygon mirror 14 fθ lens 15 Photoreceptor 16 Reflector 17 Start position detector or BD detector 18 Print medium or paper 19 Slice level 20 Laser emitter 21 Inverter 22 Output current control transistor 23 Amplifier 25 Light emission control transistor 26 Output control section 27 Constant value output section 28 Selection section ND terminal Print density signal terminal PR terminal Print signal terminal PRZ Print section BD terminal BD timing signal input terminal BDZ
BD detection unit P Writing reference point P' Writing position LZ Printing control circuit AM Inverting amplifier I1 Printing drive current I2 Bias current I3 Laser emitter current I4 I5 Laser emitter current Δt Timing difference ΔL Variation in writing position

Claims (2)

[Claims] 1. A laser image recording device comprising a print density signal and a print signal that control a print drive current (I1), and the print density signal and BD timing signal that control a bias current (I2), A printing laser control circuit (LZ) that amplifies a printing density signal that changes the printing density to a positive magnification of a predetermined value; An inverting amplifier (AM) is provided to amplify the magnification, and even when the printing density setting is changed, the printing drive current ( A laser image recording device characterized in that the sum of I1) and bias current (I2) is kept constant and supplied to a laser emitter (12). 2. A laser image recording device comprising a laser emitter (12) that emits light according to an input signal, a print signal for forming an image, and a BD timing signal for detecting a writing start position of the print signal. Then, the laser emitter (
12) constant value output section (
27) and an output control unit (26) that sets the print density using the resolution signal and the density signal and sends out an arbitrary laser output value.
, the constant value output section (27) and the output control section (26).
) is selected by the BD timing signal.
) A laser image recording device comprising: