JP3520898B2 - Laser image exposure device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser image exposure apparatus which forms an image by exposing a recording medium such as a photoconductor using a semiconductor laser array composed of a plurality of semiconductor lasers as a light source.

[0002]

2. Description of the Related Art Conventionally, in an image exposure apparatus such as a printer or a copying machine, a digital optical system including a single light source or a plurality of light sources is used to expose a recording medium such as a photoconductor in accordance with input image information. Forming an image. In a laser recording device using a semiconductor laser as a light source, the dot density of the laser beam is increased to increase the resolution, and one dot is multi-valued to reproduce a halftone, so that one pixel has multiple levels. A method of expressing the tone of a tone is known. Laser power modulation for controlling the light intensity of the laser and pulse width modulation for controlling the light emission time of the laser are generally used as the laser modulation method for performing multi-valued.

Due to the characteristics of semiconductor lasers, the emission threshold current (It) may vary depending on variations in elements, temperature, and changes over time.
h) and slope efficiency (δPo / δIop) change.
Therefore, in the laser recording apparatus, it is necessary to control the drive current of the semiconductor laser and to stably control the light intensity to a predetermined value in order to maintain good image quality.

As a method of controlling a semiconductor laser, a laser beam or a part of the laser beam is received by an optical sensor, a negative feedback closed loop is formed, and a drive current is controlled so that a predetermined light intensity is obtained. It is common to drive a semiconductor laser to expose a recording medium to form an image.

Further, in the above-mentioned pulse width modulation for controlling the light emission time of the laser, there is a phenomenon that the light rising output of the semiconductor laser is delayed as compared with the modulation frequency, and the image quality is deteriorated because a sufficient exposure amount cannot be obtained. It was happening. In order to solve such a problem, for example, Japanese Patent Laid-Open No. 3-113
Japanese Patent Laid-Open No. 472 and Japanese Patent Laid-Open No. 4-356986 propose a method of constantly supplying a bias current having a specific current value to the semiconductor laser to improve the light rising characteristic of the semiconductor laser.

In this case, the bias current is set to the light emission threshold current (Ith) or less, and the light emission threshold current (It) is set at the time of image formation.
h) The above current is applied to expose the recording medium with the semiconductor laser in the laser emission state. The bias current is set near the light emission threshold current (Ith) because it is necessary to further improve the light rising characteristics of the semiconductor laser as the pulse width modulation frequency increases due to the increase in process speed and the density of dots.

Such a method is used in a general semiconductor laser image exposure apparatus. In this type of device, a laser beam from a semiconductor laser is applied to a polygon mirror, and emitted light is continuously scanned in the circumferential direction of the polygon mirror in accordance with the rotation of the polygon mirror. The image is two-dimensionally exposed by being irradiated in the axial direction of the recording medium which moves relatively in the sub-scanning direction.

On the other hand, as another laser image exposure apparatus, one using a semiconductor laser array as a light source has been proposed. The semiconductor laser array is equipped with the same number of semiconductor lasers as the dots for the image width in the main scanning direction and a smaller number of semiconductor lasers than the dots for the image width in the sub-scanning direction orthogonal to the semiconductor laser array. An image is exposed on a recording medium that moves relatively in the scanning direction.

In such an image exposure apparatus using a semiconductor laser array, the drive current of the semiconductor laser array is controlled in order to maintain a good image quality, as in the semiconductor laser image exposure apparatus having a general structure, and a plurality of semiconductor laser array exposure currents are controlled. The light intensity is stably controlled to a predetermined value. Here again, in order to improve the light rising characteristics of the plurality of semiconductor laser arrays, it is necessary to constantly supply a bias current to the semiconductor lasers.

[0010]

However, when the method of constantly supplying the bias current to the semiconductor laser is applied to the semiconductor laser array, it has been found that there are the following problems. That is, when a bias current equal to or less than the light emission threshold current is supplied to the semiconductor laser, the semiconductor laser emits weak spontaneous emission LED light. In a general semiconductor laser image exposure apparatus, the emitted light is continuously scanned in the circumferential direction of the polygon mirror in accordance with the rotation of the polygon mirror that rotates at a high speed. The exposure amount is not enough to form an image on the surface.

However, in the semiconductor laser array image exposure apparatus, the exposure amount on the recording medium is a value obtained by integrating the energy enough to form an image, even with the LED light by the bias current, and the entire recording medium is exposed. The image quality deteriorates significantly, such as the image density becoming high .

Therefore, it is an object of the present invention to provide a laser image exposure apparatus which uses a semiconductor laser array as a light source and which can obtain an image of good rising characteristics and high image quality.

[0013]

The above-mentioned object is achieved by a laser image exposure apparatus in which, before the semiconductor laser array is caused to emit light, a bias equal to or less than the emission threshold of the semiconductor laser array is given to the semiconductor laser array for a predetermined period. To be done. Here, the predetermined period is a period in which the integrated value of the energy of the LED light emitted by the semiconductor laser due to the bias does not become the exposure amount for forming an image on the recording medium. By doing so, L is maintained while maintaining the good light rising characteristics of the semiconductor laser, which is the effect of the bias.
Inconvenience caused by generation of ED light can be solved.

A semiconductor laser driving device used in a laser image exposure apparatus includes a means for setting the amount of light emitted from a semiconductor laser array, a drive pulse generating means for instructing the timing of turning on / off the light emission of the semiconductor laser array, and a semiconductor device. A means for setting a bias below the emission threshold of the laser array and a drive pulse generating means for instructing the timing of turning on / off the bias below the emission threshold of the semiconductor laser array are provided. The timing for turning on the bias below the light emission threshold of the semiconductor laser array is earlier in time than the timing for turning on the light emission of the semiconductor laser array,
The bias can be turned on only for a time when the integrated value of the energy of the LED light due to the weak spontaneous emission emitted from the semiconductor laser due to the bias does not reach the exposure amount for forming an image on the recording medium. The timing of turning off the bias is the same as the timing of turning on or off the light emission of the semiconductor laser array,
Or after the emission of the semiconductor laser array is turned off,
This is before the integrated value of the energy of the LED light emitted by the semiconductor laser due to the bias reaches the exposure amount for forming an image on the recording medium.

Further, since the laser image exposure apparatus is provided with the light quantity detecting means of the semiconductor laser array, the light quantity of the semiconductor laser array and the bias below the light emission threshold of the semiconductor laser array can be controlled by the output of the light quantity detecting means. Further, the light emission timing of the semiconductor laser array and the bias timing below the light emission threshold of the semiconductor laser array can be controlled by the output of the light amount detecting means. The amount of light emitted from the semiconductor laser array and the setting of the bias below the light emission threshold are controlled by the current flowing through the semiconductor laser array or the voltage applied to the semiconductor laser array.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a laser image exposure apparatus according to the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a diagram showing the overall configuration of a laser image exposure apparatus according to the present invention. 1A is a top view of the laser image exposure apparatus, FIG. 1B is a side view, and FIG. 1C is an enlarged front view of the semiconductor laser array package 10. (C)
As shown in FIG. 1, the semiconductor laser array 10a is located in the substantially central portion of the package 10, and the semiconductor laser 1
A plurality of 0b are arranged on the array.

The semiconductor laser 10b includes an LD drive circuit 20.
Driven by. The LD drive circuit 20 modulates each semiconductor laser 10b according to the input image data 21,
The plurality of modulated laser beams are condensed by the field lens 11 and magnify the image via the lens array 12 to form an image on the rotating recording medium 13. As a result, the image on the recording medium 13 is two-dimensionally exposed. A part of the plurality of laser beams is reflected by the beam splitter 14, the emission intensity thereof is monitored by the photodiode 16 through the condenser lens 15, and the value thereof is fed back to the LD drive circuit 20. The LD drive circuit 20 detects the weak LED light spontaneously emitted by the semiconductor laser 10b by the bias below the emission threshold applied to the semiconductor laser array 10a before the timing when the semiconductor laser array 10a starts emitting light for image formation. The bias is supplied only during the time when the integrated value of the energy of does not reach the exposure amount for forming an image on the recording medium 13. Details of the circuit configuration for this will be described below.

FIG. 1 is a block diagram showing a first embodiment of an LD drive circuit according to the present invention. In the configuration of FIG. 1, the semiconductor laser array 1 is composed of n rows × m columns of semiconductor laser elements LD (1,1) to LD (n, m).
The LD drive circuit includes a setter 8-1 to 8-m for setting the amount of light emitted from the semiconductor laser array 1, and the semiconductor laser array 1
Pulse generators 6-1 to 6-m for instructing the timing of turning on / off the light emission of the semiconductor laser, and a setter 9-1 to setting a bias equal to or less than the light emission threshold of the semiconductor laser array 1.
9-m, drive pulse generators 7-1 to 7-m for instructing the timing of turning on / off the bias below the emission threshold of the semiconductor laser array 1, and the semiconductor laser array 1
Circuits 4-1 to 4-m for transmitting the amount of emitted light or a bias equal to or less than the light emission threshold of the semiconductor laser array 1, and pulse generators 5-1 to 5-n for selecting a driving row of the semiconductor laser array 1. Equipped with. The semiconductor laser array 1 is
The cathode is connected to pulse generators 5-1 to 5-n for selecting a driving row of the semiconductor laser array 1 via n row-direction wirings 3-1 to 3-n. Further, the anode electrode is the amount of light emitted from the semiconductor laser array 1 or the semiconductor laser array 1 through the m column-directional wirings 2-1 to 2-m.
Of the circuits 4-1 to 4-for transmitting biases below the light emission threshold of
connected to m.

FIG. 3 shows setting devices 8-1 to 8-m for setting the amount of light emitted from the semiconductor laser array 1 in FIG. 1 and setting devices 9-1 to 9 for setting biases below the light emission threshold of the semiconductor laser array 1. It is a structural example of -m. In FIG. 3, the D / A converter 17 converts the 8-bit light amount setting data digitally given by a controller (not shown) into an analog value and sends it to the buffer 18. The number of bits of the light amount setting data does not need to be 8 bits and can be changed according to the application. Further, when the light amount setting data is given in an analog form from the controller, the D / A converter 17 can be omitted and the light amount setting data can be directly connected to the buffer 18. The buffer 18 is D /
It receives the output of the A converter 17 and outputs a light amount set value. The main role of the buffer 18 is to secure a drive capacity sufficient to drive the semiconductor laser array 1 connected to the next stage.

Driving pulse generators 6-1 to 6-m for instructing the timing of turning on / off the light emission of the semiconductor laser array 1 in FIG. 1 and a bias below the light emission threshold of the semiconductor laser array 1 are turned on / off. The drive pulse generators 7-1 to 7-m for instructing the timing to perform, and the pulse generators 5-1 to 5-n for selecting the drive row of the semiconductor laser array 1 are respectively configured by switching circuits. Therefore, each switching circuit is turned on / off at a timing given by a controller (not shown).

FIG. 4 is a diagram for explaining a driving method of the semiconductor laser array 1 in the first embodiment. The description will be given for one semiconductor laser in the semiconductor laser array, but other semiconductor lasers are driven in the same manner. FIG. 4A shows an operation waveform of the pulse generator 5-1.
(B) is a diagram showing an operation waveform of the drive pulse generator 7-1 for bias, and (c) is a diagram showing an operation waveform of the drive pulse generator 6-1 for emitting semiconductor laser array. Each waveform is initially
It is off. At time t1, when the pulse generator 5-1 in (a) and the drive pulse generator 7-1 for bias in (b) are turned on, a current due to a bias equal to or lower than the light emission threshold flows through the semiconductor laser array 1. From time t1 to T
At time t2 when b time has elapsed, the pulse generator 5-1 of (a) is kept on, the drive pulse generator 7-1 for bias of (b) is turned off, and the semiconductor laser array light emission of (c) is performed. When the drive pulse generator 6-1 is turned on, a drive current flows through the semiconductor laser array 1. At time t3 when Td has elapsed from time t2, when the pulse generator 5-1 of (a) is turned off and the drive pulse generator 6-1 for semiconductor laser array emission of (c) is turned off, the semiconductor laser array 1 No current flows through it.

FIG. 5 is a waveform diagram of a current flowing through the semiconductor laser array 1 when the semiconductor laser is driven at the timing shown in FIG. In FIG. 5, Ib is a current due to a bias below the emission threshold of the semiconductor laser, and Id is a driving current of the semiconductor laser. The current Ib and the drive current Id due to this bias are determined as follows. First, the value of the setter 8-1 for setting the amount of light emitted from the semiconductor laser array 1 is set to 0 to turn on / off the light emission of the semiconductor laser array 1.
The drive pulse generator 6-1 for instructing the timing of turning off is turned on, and the drive pulse generator 7-1 for instructing the timing of turning on / off the bias below the emission threshold of the semiconductor laser array 1 is turned off. , The pulse generator 5-1 for selecting the drive row of the semiconductor laser array 1 is turned on. The value of the setter 8-1 for setting the amount of emitted light of the semiconductor laser array 1, for example, 8 given to the D / A converter 17
While gradually increasing the light amount setting data of bit, the emission threshold Ith is obtained by monitoring the emission intensity of the semiconductor laser array 1 by the photodiode and determining the emission threshold Ith.
When the semiconductor laser has a light amount obtained by subtracting several data, for example, 1 from the 8-bit light amount setting data given to the D / A converter 17 at that time, the current value flowing through the semiconductor laser array 1 is Ib. By further increasing the value of the setting device 8-1 for setting the amount of light emitted from the semiconductor laser array 1, the light emission intensity measured by the photodiode is displayed on the recording medium in consideration of the reflectance and transmittance of the beam splitter. The current value flowing through the semiconductor laser array 1 is Id when the amount of light is set to be formed. The current Ib and the drive current Id of the semiconductor laser array 1 are determined at a suitable time, for example, each time the recording medium 13 in FIG. The above description has been made for one semiconductor laser, but the same applies to other semiconductor lasers.

The time Tb during which a current is applied to the semiconductor laser array 1 by a bias below the light emission threshold and the time Td during which a drive current is applied to the semiconductor laser array 1 will be described. The time Tb during which a current with a bias equal to or lower than the light emission threshold is passed through the semiconductor laser array 1 is determined as follows.
As described above, since the exposure amount of the recording medium is determined by the integrated value of the energy of the irradiated laser, the integrated value of the energy of the LED light due to the bias current supplied to the semiconductor laser array 1 is the exposure value that forms an image on the recording medium. The time Tb during which a current is applied to the semiconductor laser array 1 by a bias equal to or less than the light emission threshold value is set so as to be equal to or less than the amount. That is,
Assuming that the exposure amount for forming an image on the recording medium is P, a value obtained by dividing P by the current Ib due to the bias below the emission threshold of the semiconductor laser array 1 determined as described above emits light to the semiconductor laser array 1. It becomes the upper limit of the time Tb during which the current is caused to flow by the bias below the threshold value. Further, the time Td during which the drive current is passed through the semiconductor laser array 1 is the light emission time of the laser controlled according to the image information of the pulse width modulation. Specifically, Tb is about 1 μs and Td is about 0.1 μs. The interval between Td and the next Td is about 130 μs.

FIG. 6 is a block diagram showing a second embodiment of the LD drive circuit according to the present invention. In the configuration of FIG. 6, the same parts as those in FIG. 1 are designated by the same reference numerals and symbols. This circuit configuration is different from that of the first embodiment in addition circuits 19-1 to 19-m for adding the amount of light emitted from the semiconductor laser array 1 and the bias below the light emission threshold of the semiconductor laser array 1.
The second embodiment is different from the first embodiment in that it is arranged.

FIG. 7 is a diagram for explaining a driving method of the semiconductor laser array 1 in the second embodiment. The description will be given for one semiconductor laser in the semiconductor laser array, but other semiconductor lasers are driven in the same manner. FIG. 7A shows the operation waveform of the pulse generator 5-1.
(B) is a diagram showing an operation waveform of the drive pulse generator 7-1 for bias, and (c) is a diagram showing an operation waveform of the drive pulse generator 6-1 for emitting semiconductor laser array. Each waveform is initially
It is off. At time t1, when the pulse generator 5-1 in (a) and the drive pulse generator 7-1 for bias in (b) are turned on, a current due to a bias equal to or lower than the light emission threshold flows through the semiconductor laser array 1. From time t1 to T
At time t2 when b hours have passed, the pulse generator 5-1 of (a) is kept on, the drive pulse generator 7-1 for bias of (b) is kept on, and the semiconductor laser of (c) is When the drive pulse generator 6-1 for array light emission is turned on, a current obtained by adding a drive current and a current due to a bias equal to or less than the light emission threshold value flows through the semiconductor laser array 1. At time t3 when Td time has elapsed from time t2, the pulse generator 5-1 in (a) is turned off, the drive pulse generator 7-1 for bias in (b) is turned off, and the semiconductor laser array in (c) is turned on. When the drive pulse generator 6-1 for light emission is turned off,
No current flows through the semiconductor laser array 1.

FIG. 8 shows the semiconductor laser array 1 when the semiconductor laser array 1 is driven at the timing shown in FIG.
FIG. 7 is a waveform diagram of a current flowing through the. In FIG. 8, Ib is a current due to a bias below the light emission threshold of the semiconductor laser array 1, and Id is a current of a value obtained by adding a current due to a bias below the light emission threshold of the semiconductor laser array 1 and a drive current of the semiconductor laser array 1. Ib and I in the second embodiment
d is determined in the same manner as in the first embodiment. Further, Tb and Td in the second embodiment are determined in the same manner as in the first embodiment.

FIG. 9 is a diagram for explaining another driving method of the semiconductor laser array 1 in the second embodiment. The description will be given for one semiconductor laser in the semiconductor laser array, but other semiconductor lasers are driven in the same manner. 9A is an operation waveform of the pulse generator 5-1. FIG. 9B is an operation waveform of the drive pulse generator 7-1 for bias. FIG. 9C is a drive pulse generator 6- for emitting light from the semiconductor laser array. It is a figure which shows the operation waveform of 1. Each waveform is initially in the off state. At time t1, when the pulse generator 5-1 in (a) and the drive pulse generator 7-1 for bias in (b) are turned on, a current due to a bias equal to or lower than the light emission threshold flows through the semiconductor laser array 1. At time t2 when Tb1 time has elapsed from time t1, the pulse generator 5-1 of (a) is kept on, the drive pulse generator 7-1 for bias of (b) is kept on, (c). When the drive pulse generator 6-1 for emitting light from the semiconductor laser array is turned on, a current obtained by adding the drive current and the bias current equal to or less than the light emission threshold value flows through the semiconductor laser array 1. At time t3 when Td time has elapsed from time t2,
Leave the pulse generator 5-1 in (a) on and (b)
When the driving pulse generator 7-1 for biasing the semiconductor laser array is turned on and the driving pulse generator 6-1 for semiconductor laser array light emission in (c) is turned off, the semiconductor laser array 1 receives a bias below the light emission threshold value. An electric current flows. At time t4 when Tb2 has elapsed from time t3, when the pulse generator 5-1 of (a) is turned off and the drive pulse generator 7-1 for bias of (b) is turned off, the semiconductor laser array 1
No current flows through it.

FIG. 10 shows a current flowing through the semiconductor laser array 1 when the semiconductor laser array 1 is driven at the timing shown in FIG. In FIG. 10, Ib is a current due to a bias below the emission threshold of the semiconductor laser array 1,
Id is a current of a value obtained by adding a drive current of the semiconductor laser array 1 with a current due to a bias equal to or less than the light emission threshold of the semiconductor laser array 1. Ib and Id in the second embodiment are determined in the same manner as in the first embodiment. Further, Tb1 and Td in the second embodiment are determined in the same manner as in the first embodiment, and Tb2 is set to Tb1 or less.

In these embodiments, the amount of light emitted from the semiconductor laser array and the bias below the light emission threshold value may be controlled by the current flowing through the semiconductor laser array.
It may be controlled by voltage, or may be controlled by current and voltage.

Other than the circuit configuration shown in this embodiment, if the current flowing through one semiconductor laser of the semiconductor laser array is the circuit configuration shown in FIG. 5, FIG. 8 and FIG. It's not limited.

In the laser image exposure apparatus of the present invention, the timing for turning on the bias below the light emission threshold of the semiconductor laser array is earlier than the timing for turning on the light emission of the semiconductor laser array, and the semiconductor laser emits due to the bias. The bias can be turned on only during a time when the integrated value of the energy of the LED light due to the weak spontaneous emission does not reach the exposure amount for forming an image on the recording medium. The bias is turned off at the same time as the light emission of the semiconductor laser array is turned on or off, or after the light emission of the semiconductor laser array is turned off, and the LED light of weak spontaneous emission emitted by the semiconductor laser by the bias is emitted. Since the integrated value of energy is before the exposure amount for forming an image on the recording medium, the image quality is not significantly deteriorated by the bias current, and the light rising characteristic of the semiconductor laser, which is the effect of the bias current, is improved and the process speed is improved. Increases and higher dot densities can be implemented. Further, since the bias on time is extremely shorter than that of the conventional case, it can contribute to the reduction of power consumption.

[0033]

According to the present invention, an image exposure apparatus using a semiconductor laser array as a light source can obtain an image with good rising characteristics and high image quality.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an LD drive circuit according to the present invention.

2A and 2B are views showing the overall configuration of a laser image exposure apparatus according to the present invention, in which FIG. 2A is a front view and FIG. 2B is a side view.
(C) is an enlarged view of a main part.

FIG. 3 is a configuration example of a setting device that sets the amount of light emitted from the semiconductor laser array and a setting device that sets a bias that is less than or equal to the light emission threshold of the semiconductor laser array.

FIG. 4A is an operation waveform of a pulse generator 5-1;
(B) is a diagram showing an operation waveform of the drive pulse generator 7-1 for bias, and (c) is a diagram showing an operation waveform of the drive pulse generator 6-1 for emitting semiconductor laser array.

5 is a waveform diagram of a current flowing through the semiconductor laser when the semiconductor laser is driven at the timing shown in FIG.

FIG. 6 is a block diagram showing a second embodiment of an LD drive circuit according to the present invention.

7 (a) is an operation waveform of a pulse generator 5-1, FIG.
(B) is a diagram showing an operation waveform of the drive pulse generator 7-1 for bias, and (c) is a diagram showing an operation waveform of the drive pulse generator 6-1 for emitting semiconductor laser array.

8 is a waveform diagram of a current flowing through the semiconductor laser when the semiconductor laser is driven at the timing shown in FIG.

9 (a) is an operation waveform of a pulse generator 5-1, FIG.
(B) is a diagram showing an operation waveform of the drive pulse generator 7-1 for bias, and (c) is a diagram showing an operation waveform of the drive pulse generator 6-1 for emitting semiconductor laser array.

10 is a waveform diagram of a current flowing through the semiconductor laser when the semiconductor laser is driven at the timing shown in FIG.

[Explanation of symbols]

1 Semiconductor laser array 2-1 Column direction wiring 2-2 Column direction wiring 2-m column direction wiring 3-1 Row direction wiring 3-2 Row direction wiring 3-m row direction wiring 4-1 Transmission circuit 4-2 Transmission circuit 4-m transmission circuit 5-1 Drive row selection pulse generator 5-2 Drive row selection pulse generator 5-n drive row selection pulse generator 6-1 Drive pulse generator 6-2 Drive pulse generator 6-m drive pulse generator 7-1 Drive pulse generator 7-2 Drive pulse generator 7-m drive pulse generator 8-1 Emission light intensity setting device 8-2 Emission light intensity setting device 8-m emission light intensity setting device 9-1 Bias setting device 9-2 Bias setter 9-m bias setting device

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideaki Ashikaga Inventor Hideaki Ashikaga 430 Nakai-cho, Ashigaragami-gun, Kanagawa Green Tech Nakakai Fuji Xerox Co., Ltd. (56) References JP-A-9-183249 (JP, A) JP-A-9-131918 (JP, A) JP-A-8-83950 (JP, A) JP-A-8-116119 (JP, A) JP-A-5-190948 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2/44 B41J 2/45 B41J 2/455 H01S 5/042

Claims (11)

(57) [Claims] 1. A laser image exposure apparatus for exposing a recording medium by driving a semiconductor laser array based on image data, wherein the semiconductor laser array is emitted from before the emission of the semiconductor laser array to at least the emission of the semiconductor laser array. to the light emission threshold following bias array was set to give a predetermined period to said semiconductor laser array, and the predetermined period, the image in the integral value is the recording medium of the energy of the LED light individual semiconductor laser is released by the bias The laser image exposure apparatus is characterized in that it is a period in which the exposure amount does not become a value. 2. The laser image exposure apparatus according to claim 1, wherein the amount of light emitted from the semiconductor laser array and the setting of the bias equal to or less than the light emission threshold are controlled by a current flowing through the semiconductor laser array. 3. The laser image exposure apparatus according to claim 1, wherein the amount of light emitted from the semiconductor laser array and the bias below the light emission threshold are controlled by the voltage applied to the semiconductor laser array. 4. In a laser image exposure apparatus that exposes a recording medium by driving a semiconductor laser array based on image data, the semiconductor laser array is turned on at a timing at which a bias equal to or less than an emission threshold of the semiconductor laser array is turned on. The timing of turning on the light emission of the array is earlier than the timing of turning on the light of the array, and the timing of turning off the bias is not earlier than the timing of turning on the light emission of the semiconductor laser array, and
The laser image exposure apparatus, wherein the integrated value of the energy of the LED light individual semiconductor laser emits is before the exposure amount necessary for forming an image on a recording medium. 5. The timing for turning off the bias is
The laser image exposure apparatus according to claim 4, wherein the timing of turning on or off the light emission of the semiconductor laser array is adjusted. 6. The timing for turning off the bias is
The semiconductor light emitting laser array is a laser image exposure apparatus according to claim 4, characterized in that after turning off. 7. A light quantity detecting means for the semiconductor laser array is provided, and a light quantity of the semiconductor laser array and a bias below a light emission threshold of the semiconductor laser array are controlled by an output of the light quantity detecting means. The laser image exposure device according to claim 4 . 8. includes a light quantity detecting means of the semiconductor laser array, when the electric current due to light emission threshold following bias by Ri before Symbol semiconductor laser array to the output of said light quantity detecting means
The upper limit of the interval is determined.
4. The laser image exposure device according to item 4 . 9. A semiconductor laser driving device for driving a semiconductor laser array, wherein a means for setting the amount of light emitted from the semiconductor laser array and a drive pulse generation for instructing the timing of turning on / off the light emission of the semiconductor laser array. Means for setting a bias below the emission threshold of the semiconductor laser array, and drive pulse generating means for instructing the timing of turning on / off the bias below the emission threshold of the semiconductor laser array, Is turned on earlier than the timing at which the light emission of the semiconductor laser array is turned on, and the timing at which the bias is turned off is not earlier than the timing at which the light emission of the semiconductor laser array is turned on. to release a separate semiconductor <br/> body laser and by the bias The semiconductor laser drive device, wherein the integrated value of the energy of the LED light is before the exposure amount necessary for forming an image on a recording medium. 10. The semiconductor laser driving device according to claim 9, wherein the bias is turned off at the same time as the light emission of the semiconductor laser array is turned on or off. 11. The timing for turning off the bias, the semiconductor laser drive device according to claim 9, wherein the light emission of the semiconductor laser array and said <br/> that after turning off.