JPH027064B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording device that records images using a plurality of recording means.

A high-speed recording device can be obtained if the light beams from a plurality of light sources arranged in a row are deflected by a rotating polygon mirror or the like and scanned over the recording medium. On the other hand, arranging the beams in a direction perpendicular to it had the disadvantage that it was not possible to space the adjacent beams apart by more than a certain distance.

In order to eliminate such drawbacks, the present applicant has
-38130, proposed a scanning device that irradiates a recording medium with multiple beams that are not perpendicular to the sub-scanning direction.

However, when information is recorded using beams shifted in the sub-scanning direction in this way, it becomes difficult to accurately align the writing start position of each beam on the recording medium.

The present invention has been made in view of the above-mentioned points, and an object thereof is to provide a recording device that can accurately match the writing start position of an image with a simple configuration.

That is, the present invention includes: a plurality of beam generators (FIG. 2 a, b, c) that irradiate a plurality of beams modulated by a recording signal onto a recording medium; and a plurality of beams irradiated onto the recording medium. a scanning means (FIG. 1, 3) for scanning the recording medium, and in which adjacent beams of the plurality of beams irradiated onto the recording medium are arranged so as to be oblique to the scanning direction of the beams. , a plurality of modulation means (D _a , D _{b , D c in FIG. 5) for respectively modulating the plurality of beams, and a plurality of storage means (D a , D b} , D _c in FIG. 5) for storing recording signals corresponding to the plurality of beams. Figure 5 LB _a , LB _b ,
LB _c ), a detection means (FIG. 5 BD) for detecting the scanning position of the beam, and a specific modulation means among the plurality of modulation means to turn on a specific beam among the plurality of beams. A control means (CT in FIG. 5) for controlling the beam, and a position signal forming means (CT in FIG. 5) for forming one position signal based on the detection output of the detection means of the specific beam turned on by the control means.
WA); clock signal generating means (RC _a in FIG. 5) for generating multiple types of clock signals with the same period and different phases based on one position signal formed by the position signal forming means; By applying the plurality of types of clock signals generated by the clock signal generating means to the plurality of storage means, recording signals corresponding to each of the plurality of beams are read out and the plurality of beams are modulated. The present invention provides a recording device.

The present invention will be described below with reference to an embodiment of the present invention.
2 is a semiconductor array laser light source, and as shown in FIG. 2, it has a plurality of light emitting points a, b, and c, and the light emitting points are arranged in a line with an interval A. Luminous point a,
The exposure of the beams b and c can be individually controlled by image signals from the planar image signal source 8, respectively.

This beam is focused by a condensing optical system 2 and irradiated onto a rotating polygon mirror 3, and the beam reflected by this rotating polygon mirror 3 is imaged on a photosensitive drum 5 by an imaging optical system 4.

The beams a, b, and c are set at an angle θ (θ=Sin ^-1 P/MA, where P is the scanning pitch, M is the focusing optical system, and The light source 1 is arranged near the focal point of the condensing optical system 2 so as to have the magnification of the entire imaging optical system. Then, the individual light emitting point areas of the semiconductor laser array light source 1 are 10
Since it is very small, several μm or less, it can be regarded as a point light source, and a plurality of collimated laser beams can be obtained by the condensing optical system 2. For example, P=100μm, M
= 10, the angle θ is very small, and therefore the cross section of the laser beam incident on the rotating polygon mirror 3 is not very large in the direction perpendicular to the plane of rotation F of the rotating polygon mirror 3, and in the case of a single beam. It's not much different. Therefore, there is no need to increase the thickness of the rotating polygon mirror 3, and the same rotating polygon mirror as in the case of a single beam can be used.

The plurality of laser beams reflected by the rotating polygon mirror 3 are image-scanned onto the photosensitive drum 5 by the imaging lens 4, as shown in FIG. The distance between the light emitting points is A
Therefore, if the magnification of the entire optical system is M, the interval between the imaging spots is MA. Also, since the angle of the imaging spot of the array laser with respect to the scanning plane of the array is θ, the interval between the imaging spots in the direction perpendicular to the scanning is MAsin θ=P.

A plurality of such beams cross the photodetector 7 in the order of beams Lc, Lb, and La at the beginning of scanning.

Now, when information is recorded using multiple beams shifted in the main scanning direction in this way, the multiple beams cross the photodetector 7 in the order of beams Lc, Lb, and La at the beginning of scanning, so the photodetector Controlling the writing positions of each beam on the recording medium using each output of 7 requires complicated control.

This embodiment eliminates the above-mentioned drawbacks of the conventional method by scanning the beam detector with only a selected one of the plurality of beams turned on.
The object of the present invention is to provide a beam recording device that can match the writing positions of each beam on a recording medium with simple control.

The image signal source 8 in FIG. 1 will be further explained with reference to FIG.

In Fig. 5, BD indicates the beam detector,
WA is a waveform shaping circuit, CT is an unblanking signal generation circuit, CONT is a control circuit, PBF
is a page buffer circuit, CG is a character generator circuit, LDF is a line data former, DIS is a distribution circuit, CLK is a reference clock generation circuit, GT
is gate circuit I, RCa is ring counter circuit,
Ca is a gate control circuit, Ga, Gb, Gc are gate circuits, LBa, LBb, LBc are line buffer circuits,
DL1, DL2, DL3 are delay circuits, Da, Db, Dc
is a semiconductor laser modulation circuit.

Now, when the beam Lc shown in FIG. 4 enters the beam detector BD in a lit state, only one beam detection signal is derived onto the signal line SL1. Here, in order to obtain only one beam detection signal, it is assumed that only beam Lc is turned on. (Although either Lb or La may be turned on instead of Lc, in this example, the description will be made assuming that beam Lc is turned on.) Next, the beam detection signal is shaped into a rectangular pulse signal by the waveform shaping circuit WA. be done.

Next, the output of the waveform shaping circuit WA is the gate circuit GT
is applied to The gate circuit GT receives the output of the waveform shaping circuit WA and converts it into a reference clock generation circuit.
Start transmitting CLK output to ring counter RCa.

The ring counter RCa is constituted by an N-ary counter, and has N types of phases of the output of the reference clock generation circuit CLK, and transmits an output V obtained by dividing the frequency by N to the gate circuits Ga, Gb, and Gc. Here the output V
The pulse width of is equal to the pulse width for one pixel.

Next, to further explain the function of the ring counter RCa, the line buffer memories LBa, LBb, and LBc output data in synchronization with a clock signal. If one clock signal
When driving LBa, LBb, and LBc, the distance MAcosθ between adjacent light emitting points in the light beam scanning direction shown in Fig. 4 is
is required to have an integer ratio of Vs·ΔT, where the scanning speed is Vs and the pulse width of the clock signal is ΔT. However, due to the clock signal having N types of phases formed by the ring counter RCa, the line buffer memories LBa, LBb, LBc are
If driving, the distance in the light beam scanning direction is
MA cos θ can be expressed as (Vs·ΔT)/N, where the scanning speed is Vs and the pulse width of the clock signal having the N types of phases is ΔT. In other words, the distance between the adjacent light emitting points in the light beam scanning direction
It is used to correct the variation in MAcosθ up to (Vs·ΔT)/N.

Next, the gate circuits Ga, Gb, and Gc start transmitting the output from the ring counter RCa to the line buffer circuits LBa, LBb, and LBc based on the output from the gate control circuit Ca composed of counters and the like.

Gate control circuit Ca is the ring counter
After dividing the RCa output by N1, the gate circuits Ga, Gb,
Transmit gate open command signal to GC.

Here, the function of the gate control circuit Ca will be explained.

After the beam detector BD detects the beam Lc until the beam control circuit Ca generates the beam open command signal, the beams La, Lb, and Lc shown in Fig. 4 are
lD1 forward. Also, during this period, line buffer memory
Clock signals from ring counter RCa to LBa, LBb, and LBc are also prohibited.

In other words, the ring counter to be applied to the line buffer memory by the gate control circuit Ca
By inhibiting the clock signal from RCa, the delay amount of delay circuits DL1, DL2, and DL3, which will be described later, can be reduced.
It can be reduced by lD1. This is DL
1. This means that the configuration of DL2 and DL3 can be easily configured.

LBa, LBb, and LBc are line buffer memories that store dot signals M corresponding to one scanning line.
Gate circuit Ga from signal lines SL5, SL6, SL7,
By applying clock signals from Gb and Gc, dot signals are read onto signal lines SL8, SL9, and SL10 in synchronization with the applied clock signals.

Next, the dot signal read out to SL8 is applied to a delay circuit shown at DL1.

Here, assuming that the dot signal read out on SL8 forms La shown in FIG. time △T ₁
During this time, the signal is delayed by the delay circuit DL1 and then transmitted to the semiconductor laser modulation circuit Da. The method for calculating ΔT ₁ will be described later.

Also, the dot signal read out on SL9 is the fourth
Assuming that Lb shown in the figure is formed, the dot signal read out on SL9 is the time △T ₂ until the beam Lb reaches the recording start position Ws on the photosensitive drum 5.
During this period, the signal is delayed by the delay circuit DL2 and then transmitted to the semiconductor laser modulation circuit Db. The method for calculating ΔT ₂ will be described later.

Further, assuming that the dot signal read out on SL10 forms Lc shown in FIG.
The dot signal read above is delayed by the delay circuit DL3 for a time _ΔT3 until the beam Lc reaches the recording start position Ws on the photosensitive drum 5, and then transmitted to the semiconductor laser modulation circuit Dc.

Here, △T ₁ , △T ₂ , and △T ₃ are determined by the following formulas.

If la′=la−lD1, then △T ₁ = la′/Vs {However, la is the time from when the beam detector DB detects the beam LC until the beam La reaches the recording start position Ws on the photosensitive drum. .

l _D 1 is based on how the beams La, Lb, and Lc advance from when the beam detector BD detects the beam Lc until the gate control circuit Ca generates the gate open signal.

Vs is the scanning speed of the beams La, Lb, and Lc.Similarly, if lb' = lb-l _D 1, then △T ₂ = lb'/Vs lc' = lc-l _D If 1, △T ₃ = lc'/Vs. Become.

Next, the semiconductor laser modulation circuits Da, Db, and Dc output beams La, Lb, and
Lc is modulated based on the signals from the delay circuits DL1, DL2, and DL3.

In Fig. 5, CT indicates lighting control so that only the light beam Lc passes through the beam detector BD in a lit state, and the other light beams La and Lb pass through the beam detector BD in an off state. After counting a value P sufficient for all beams La, Lb, and Lc to irradiate the photosensitive drum 5, it derives a lighting signal on the signal line SL14, and this lighting signal is sent to the terminal of the drive circuit DC. By applying T1, the light beam Lc is forcibly emitted. Also, this lighting signal is controlled by the control circuit.
It is also transmitted to CONT. control circuit
When CONT receives this signal, it sends a clear signal to SL20 to initialize the gates and counters that form the shift register read clock signal.

Note that since this counter CT is cleared by the beam detection signal, the emission of the beam Lc is suppressed after the beam detector BD detects the beam Lc.

PBF is a page buffer memory that stores information equivalent to at least one page, and the character code signals belonging to the rows of this memory are sequentially read out under the control of the control circuit CONT and converted into character codes. The selected character dot pattern is selected by applying the corresponding character dot pattern to the character generator CG that has stored it, and by instructing through the signal line SL15 which line of this character dot pattern should be output. The dot signal belonging to the selected line is derived onto the signal line SL16,
This is stored in the line data generator LDF.

Once the dot signals equivalent to one line are stored in the line former LDF in this way, the dot signals for one line are stored in the line buffer LBa, LBb, or LBc under the control of the distributor. be.

Note that the new dot signals to be recorded next to the line buffers LBa, LBb, and LBc are stored using the counter.
This is performed during the period after CT counts the numerical value P until the light beam Lc is detected by the beam detector BD.

Next, line buffers LBa, LBb, and LBc synchronize with the clock signals from gate circuits Ga, Gb, and Gc, and send dot signals equivalent to one line to delay circuits DL1 and LBc.
It is transmitted to DL2 and DL3 and delayed.

The delayed dot signal is sent to the semiconductor laser modulation circuit.
Added to Da, Db, and Dc. and modulation circuit Da,
A semiconductor laser is driven via Db, Dc, and light beams La, Lb,
Lc is emitted from the semiconductor array laser light source 1.

Next, the modulated light beams La, Lb, and Lc are scanned in a direction parallel to the axis of the photosensitive drum 5, and as the photosensitive drum 5 rotates, scanning is performed in a direction perpendicular to the axis of the photosensitive drum 5. A high quality image for one page is formed on the photosensitive drum.

Here, the time when the reading of the dot signal from the line buffer LBc is completed and the delay by the delay circuit DL1 is completed is equal to the time when the beam Lc reaches the recording stop position WT shown in FIG. The time when the reading of the dot signal is completed and the delay by the delay circuits DL2 and DL3 is completed is equal to the time when the beams Lb and La each reach the position WT.

As described in detail above, according to the present invention, it is possible to accurately match the writing start positions of images with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a top view of a beam recording device to which the present invention is applied, FIG. 2 is a perspective view of a light source, FIGS. 3 and 4 are front views of beams showing the arrangement of multiple beams, and FIG. 5 is an image signal FIG. 3 is a circuit block diagram of the source. Here, 1 is a semiconductor laser array light source, 5 is a photosensitive drum, Ca is a gate control circuit, Ga, Gb, and Gc are gate circuits, LBa, LBb, and LBc are line buffer circuits, and DL1, DL2, and DL3 are delay circuits.

Claims (1)

[Claims] 1. A device comprising: a plurality of beam generating units that irradiate a plurality of beams modulated by a recording signal onto a recording medium; and a scanning means that scans the plurality of beams irradiated onto the recording medium. In a recording device in which adjacent ones of the plurality of beams irradiated onto the recording medium are arranged obliquely with respect to the scanning direction of the beams, a plurality of modulations for respectively modulating the plurality of beams are provided. means for storing recording signals corresponding to the plurality of beams; detection means for detecting the scanning position of the beams; a control means for controlling a specific modulation means among the plurality of modulation means; and a position signal forming means for forming one position signal based on a detection output by the detection means of a particular beam turned on by the control means. and a clock signal generating means for generating a plurality of types of clock signals having the same period and different phases from each other based on one position signal formed by the position signal forming means; and the plurality of types of clock signals generated by the clock signal generating means. A recording device characterized in that the plurality of beams are modulated by reading recording signals corresponding to each of the plurality of beams by applying different kinds of clock signals to the plurality of storage means.