JPS5845978A - Printing output device - Google Patents

Abstract

PURPOSE:To obtain a printing of high quality by providing the first photoelectric converter for obtaining a horizontal synchronizing signal for deciding the printing start position of a main scanning direction and the second photoelectric converter for controlling the output at the printing time, thereby increasing the output obtained from the first converter larger than the drive power at the printing time. CONSTITUTION:The output obtained from the first photoelectric converter 15 is amplified by an amplifier 18, is shaped by a pulsating circuit 19 as a horizontal synchronizing signal BD. The output obtained from the second photoelectric converter 16 is detected at the peak by a monitor detector 20, is compared with the output of a reference value setting circuit 21, and is amplified by an amplifier 22 to become equal to the reference value. Then, the driving current of a semiconductor laser 1 is controlled by a bias current setting circuit 23 and AC driving circuits 24, 25.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print output device using a light source such as a laser.
In particular, it relates to a print output device equipped with a circuit that drives and controls a semiconductor laser so as to obtain print output with high print quality. For example, a printing device using a semiconductor laser generally has a first
As shown in the figure, a laser beam from a light source 1 is reflected by a polyhedral lens 2, and the light is condensed and scanned over a photosensitive element medium 4 through a lens 3.
After forming the latent image, the latent image is developed, transferred to paper, fixed, and output. Note that both the photosensitive element medium 4 and the polyhedral mirror 2 are rotating.

In the above print output device, a part of the scanning light is reflected as a horizontal synchronization signal by a mirror 5 provided apart from the photosensitive element medium 4, and the reflected light is received by a photodiode 7 through a slit 6. As the starting position of printing, on the other hand,
Printing is performed by a video signal at the printing area on the photosensitive element medium 4.

FIG. 2 shows a semiconductor laser drive circuit, and FIG. 3 shows its driving relationship. In FIG. 3, the photodiode 7 first obtains a VPH waveform, which is amplified by the amplifier 8 and shaped by the pulse generator 9 to obtain a BD flaw signal. On the other hand, the monitor detection circuit 10 obtains the VPH waveform. The peak voltage obtained is compared with the output of the reference value setting circuit 11, and the amplifier 12 adjusts the peak voltage to the reference value, and the bias current setting circuit 13 and the AC drive circuit 14 control the drive current of the semiconductor laser 1. It's in control.

As described above, the print output device drives the semiconductor laser 1 with the same current as the BD signal that determines the printing start position in the scanning direction and the video signal in the printing area. However, as the sensitivity of recent photosensitive element media 4 has improved, the required printing energy has become smaller, and the amount of light received by the photodiode 7 has become smaller. As a result, the photodiode 7 cannot obtain a sharp waveform, and the BD signal that determines the printing start position cannot be obtained with sufficient accuracy, resulting in a decrease in printing quality.

An object of the present invention is to provide a first photoelectric conversion element that receives a horizontal synchronization signal that determines the printing start position in the main scanning direction, and a second photoelectric conversion element that controls the output during printing, so that the output that can be obtained from the first photoelectric conversion element is provided. It is an object of the present invention to provide a print output device that has a large drive current when printing output and has high print quality.

A feature of the present invention is that a first photoelectric conversion element that determines the print start position on the photosensitive element medium and a second photoelectric conversion element that controls the output during printing are provided, and the first photoelectric conversion element has a large output regardless of printing. The above object is achieved by including a circuit for driving the light source so that the second photoelectric conversion element obtains the amount of output required by the photosensitive element medium during printing.

The present invention will be described below with reference to examples.The present invention takes advantage of the fact that the laser drive currents during the horizontal synchronization signal detection period and the printing period do not have to be at the same level, and in order to obtain respective outputs. As shown in FIG.
5 and 16, and a slit 17 is provided in them.

FIG. 5 shows a circuit diagram of one embodiment of the print output device of the present invention, and FIG. 6 shows its driving relationship.

In FIGS. 5 and 6, the output obtained from the first photoelectric conversion element IS is amplified by an amplifier 18, and shaped by a pulse forming circuit 19 to form a horizontal synchronizing signal BD.
The output obtained from 6 is peak detected by the monitor detection circuit 2o, compared with the output of the reference value setting circuit 21, amplified by the S amplifier 22 to be equal to the reference value, and then connected to the bias current setting circuit 23 and AC drive. The circuits 1 and 2 (24, 25) control the driving current of the semiconductor laser 1 as explained in FIG. 7 below.

Figure 7 shows the relationship between semiconductor laser output characteristics and drive current! In the diagram showing the output characteristic A of the 0 laser, where the horizontal axis is the current l, the vertical axis is the laser output above, and the time t is below,
Even if the current is passed up to the threshold current ith of the threshold ^hold, the photosensitive element medium will not feel C is superimposed and flowed, and the bias is applied to the 1st.
It absorbs increases and decreases in the output of the second conversion element.

As described above, since the first photoelectric conversion element 15 that controls the drive current of the semiconductor laser 1 receives a large amount of light, a steep waveform can be obtained. As a result, a uniform horizontal synchronization signal with good B/a and low amount of jitter is obtained, which enables high print quality print output.Also, the output of the second photoelectric conversion element 16] is set to the output necessary for printing. (K), it can be used even if the sensitivity of the photosensitive element medium is low.

The present invention has been described above with reference to the embodiments. According to the present invention, a first photoelectric converting element determines the printing start position on a photosensitive element medium, and a second photoelectric converting element controls the appearance of one character. By providing a print output device with a circuit for driving a light source so as to obtain the amount of light required by each of the first photoelectric conversion elements, it is highly effective to obtain print output with high print quality.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a conventional printing device using a semiconductor laser, Fig. 2 is its circuit diagram, Fig. 3 shows its driving relationship, and Fig. 4 is a printing device using the semiconductor laser of the present invention. FIG. 5 is a perspective view showing one embodiment of the device; FIG. 5 is a circuit diagram thereof; FIG. 6 is a diagram showing its driving/driving relationship; and FIG. 7 is a diagram showing output characteristics of a semiconductor laser.

Claims (1)

[Claims] In an apparatus for printing out a latent image on a photosensitive element medium obtained by scanning the medium using a light source such as a laser, a first step for determining a printing start position with respect to the photosensitive element medium is provided.
A photoelectric conversion element and a second photoelectric conversion element that controls the output during printing are provided, the first photoelectric conversion element outputs a large output regardless of printing, and the second photoelectric conversion element controls the output of the photosensitive element medium during printing. A printing output device 0 characterized by comprising a circuit for driving the light sources so as to obtain a required amount of output respectively.