The application is that application number is 01802651.6, the applying date is September 4 calendar year 2001, denomination of invention is divided an application for " self-scanning light-emitting element array and driving method thereof and drive circuit " patent application.
The specific embodiment
Below according to the description of drawings embodiments of the invention.
(first embodiment)
Present embodiment is the circuit structure that does not change the self-scanned light-emitting device array chip of Fig. 3, is the driving method of 2 self-scanning light-emitting element array and make the luminous light-emitting component simultaneously of each chip.
First example
The light pen that will possess a plurality of light-emitting components that are arranged in of self-scanned light-emitting device array chip of 1200dpi that Fig. 3 is arranged, 256 light-emitting components, waveform example by the 1200dpi resolution drive is illustrated in Fig. 4, is illustrated in Fig. 5 by the waveform example of 600dpi resolution drive.Present embodiment is by using this 2 kinds of waveforms respectively, when the self-scanning light-emitting element array that uses 1200dpi is pressed the resolution ratio presentation video of 600dpi, 2 adjacent light-emitting components are regarded as 1 cell block and lighted the printing speed that doubles when realizing 1200dpi resolution ratio thus simultaneously.
In addition, in this example, clock pulses 1, 2 share for a plurality of self-scanning light-emitting element chips that constitute light pen.
At first drive waveforms under the 1200dpi resolution ratio is described referring to Fig. 4.Write signal
IWaveform repeat with period T, the waveform of transport unit clock pulses 1, 2 repeats with cycle 2T.Time t among the figure
aBe at transport unit IGCT T
N-1During conducting, for making next IGCT T
nConducting and overlapping time of needing; Time t
bThen be from transport unit IGCT T
nBe conducting to the stand-by time of illuminating part IGCT Ln conducting.At this t
a, t
bDuring this time, the illuminating part IGCT can not be luminous, and can only be during surplus T-(t
a+ t
b) between luminous.The feature of these drive waveforms is " illuminating part IGCT L
nWhen luminous, the IGCT that is in conducting state is T
n".
Referring to Fig. 5 drive waveforms under the 600dpi resolution ratio is described below.This waveform is for write signal
IAnd the repetition period of transport unit clock pulses 1, 2 all is 2T.Establish adjacent transport unit IGCT T now
2n-3, T
2n-2Conducting simultaneously.Initial time t among the figure
eBe to be used to make IGCT T
2n-3Disconnect the necessary time, next time t
aBe to make IGCT T
2n-1The overlapping time that conducting is required, next again time t
eBe to make IGCT T
2n-2Disconnect the required time, next again time t
aBe to make IGCT T
2nThe overlapping time that conducting is required, and the time 2T-2 (t of surplus
a+ t
e) then be adjacent 2 illuminating part IGCT L
2n-1-With L
2nCan the simultaneously luminous time.
The feature of above-mentioned drive waveforms is " illuminating part IGCT L
2n-1With L
2nCan be simultaneously luminous, and this moment transport unit IGCT T
2n-1With T
2nConducting simultaneously ".But because 2 adjacent illuminating part IGCT L
2n-1, L
2nSimultaneously luminous, write signal
IElectric current also must divide and flow to 2 IGCTs, so the drive circuit of 1 circuit needs to have 1 electric current I when luminous according to resolution ratio
LElectric current 2I with 2 when luminous
LTwo kinds of level.
Fig. 6 represents the of above-mentioned self-scanning light-emitting element array
IThe example of the drive circuit of circuit.This drive circuit is by 60,61,3 MOSFET62-63 of 2 phase inverters, 64 and 2 current-limiting resistance R
Ia, R
IbConstitute.V
1a, V
IbBe control terminal, V
IBe lead-out terminal and with the of Fig. 3
ITerminal connects.
Set control terminal V
IaBehind the H level, lead-out terminal V
IThen through resistance R
IaWith positive supply (+V
DD) connect.Set control terminal V again
IbBe the H level, and resistance R
IaWith resistance R
IbIn parallel.If resistance R
IaWith R
IbResistance value identical, so the value of this parallel resistance becomes 1/2 of 1 resistance value, thus
IElectric current becomes 2 times.
So, according to this drive circuit, for making 1 illuminating part IGCT luminous, can be with control terminal V
IaBe made as the H level.And be to make 2 adjacent IGCTs simultaneously luminous, then can be with control terminal V
Ia, V
IbBe set at the H level simultaneously.
Fig. 7 represents by 2 current source J
a, J
b, the that switch S wa, the SWb that is connected with the output of each current source forms
IAnother example of line drive circuit.Each switch is by control terminal V
Ia, V
IbThe control of breaking/lead to.Promptly when control terminal is the H level, switch connection.
By making control terminal V
IaBe the H level, switch S wa is logical, current source J
aElectric current flow to
ITerminal.Have again, establish control terminal V
IbBe the H level, from current source J
aWith J
bHave electric current to flow out, the electric current of establishing each current source is identical, flows to with regard to 2 times electric current is arranged
ITerminal.
So according to this drive circuit, identical with the drive circuit of Fig. 6, for making 1 IGCT luminous, can be with control terminal V
IaBe made as the H level; And be to make 2 adjacent IGCTs simultaneously luminous, then can make control terminal V
Ia, V
IbBe set to the H level simultaneously.
Now consider to adopt the drive circuit of Fig. 6 or Fig. 7, the resolution ratio of press 1200dpi * 1200dpi (main scanning direction * sub scanning direction) drives the situation that per minute prints 20 A4 paper (vertically) according to the drive waveforms of Fig. 4.Vertical suitable approximately 13800 row of A4 paper.Owing to be to have scanned its (20 of per minute) with 3 seconds, the printing time of every row is 220 μ s, and the period T of each illuminating part IGCT becomes 850ns, establishes t
a=t
b=100ns, but the about 650ns of the fluorescent lifetime of 1 illuminating part IGCT then.
The situation that next consideration is printed with the resolution ratio of 600dpi * 1200dpi (resolution ratio of sub scanning direction is identical).At this moment, the drive waveforms of pressing Fig. 5 drives, and establishes t
a=t
b=100ns, 2T=650ns+400ns then, and the printing time of every row becomes 1050ns * 128=134 μ s.The time of about 1/1.6 when this is 1200dpi * 1200dpi,, then can obtain 1.6 times print speed printing speed if establishing resolution ratio is 600dpi * 1200dpi.
If t
a, t
b, t
eLittle with respect to fluorescent lifetime to negligible degree, then can make print speed printing speed roughly improve 1 times.
As mentioned above, according to this example, because can not change the light-emitting device array of circuit by using 1200dpi can be in the hope of the image of 600dpi,, also can reduce cost by parts generalization with the shaven head of 1200dpi even in the situation of the shaven head of making 600dpi special use.
The 2nd example
Illustrated that in first example clock pulses 1, 2 are for the shared situation of a plurality of self-scanned light-emitting device array chips that constitutes light pen.Because clock pulses 1, 2 are shared, so have the advantage that circuit structure is simplified.
This 2nd example considers in each self-scanned light-emitting device array chip clock pulses 1, 2 to be given independently the situation of circuit structure.Be adjacent 2 illuminating part IGCT L in example 1
2n-1With L
2nRegard 1 unit as and make it simultaneously luminous.But in this 1 unit IGCT L
2n-1Or be IGCT L
2nLuminous, utilize to former state the resolution ratio of chip to carry out high speed printing effectively.So, corresponding to each luminance, by making clock pulses 1, 2, control terminal V
Ia, V
IbWave form varies, with making the modes that 2 illuminating part IGCTs can be luminous simultaneously, can print with the original resolution ratio of chip.
The clock pulses 1, the 2 control terminal V that change have been represented among Fig. 8
Ia, V
IbFour kinds of waveform patterns 0, I, II, III.Waveform patterns 0 has been represented L
2n-1With L
2nNot luminous, waveform patterns I is IGCT L simultaneously
2n-1Luminous, waveform patterns II is IGCT L
2nLuminous, waveform patterns III is IGCT L
2n-1With L
2nSimultaneously luminous situation.
In the situation of waveform patterns 0, make clock pulses 1 be the H level, carry out the transmission of conducting state by transport unit for L level, 2, and control terminal V
Ia, V
IbCommon is the L level, allows write signal
IFormer state ground keeps the L level.At this moment, illuminating part IGCT L
2n-1, L
2nNot luminous.
In the situation of waveform patterns I, be transport unit IGCT T
2n-1Be in conducting state, make control terminal V
IaBe H level control terminal V
IbBe the L level, and make write signal
IBe the H level, make illuminating part IGCT L
2n-1Luminous, at illuminating part IGCT L
2n-1After not luminous, the conducting state that is about to transport unit transforms to IGCT T
2n
Waveform patterns II is opposite with the situation of pattern I, at first from transport unit IGCT T
2n-1Transfer to IGCT T
2nConducting state, control terminal V under this state
IaBe H level while write signal
IAlso become the H level, have only illuminating part IGCT L
2nLuminous.
The situation of waveform patterns III is identical with example 1, transport unit IGCT T
2n-1, T
2nBe in conducting state simultaneously, with control terminal V
IaWith V
IbBe made as the H level and establish write signal
IBe the H level, then illuminating part IGCT L
2n-1With L
2nSimultaneously luminous.In this waveform patterns,, flow through 2 times electric current for making 2 illuminating part IGCTs luminous.And allow control terminal V
IaWith V
IbRise to the H level simultaneously.
More than the combination example of four kinds of patterns be illustrated in Fig. 9.Represented according to clock pulses 1, 2, control terminal V
Ia, V
IbWave form varies, adjacent 2 illuminating part IGCT L
2n-1With L
2nThe situation of flicker.Zero with ● show respectively luminous with not luminous.Anyway make up this four kinds of patterns, transport unit transmits by 2 IGCTs for each piece as can be known.
According to the driving method of present embodiment, in self-scanning light-emitting element array,, under the situation that reduces resolution ratio, can improve print speed printing speed owing to can make 2 IGCTs simultaneously luminous simultaneously to each chip.
(the 2nd embodiment)
The self-scanned light-emitting device array chip that present embodiment relates to is in the circuit structure of the self-scanning light-emitting element array of Fig. 3, by additional resistance can make each chip simultaneously luminous light-emitting component number be 2.
The equivalent circuit of having represented the self-scanned light-emitting device array chip of present embodiment among Figure 10, in essence, the circuit of it and Fig. 3 is roughly the same, thereby for Fig. 3 in identical parts attached with Fig. 3 in identical label represent.
According to present embodiment, in the circuit of Fig. 3 in
IBetween the anode terminal of circuit 34 and illuminating part IGCT, be respectively equipped with the resistance R of appropriate value
AIn the self-scanning light-emitting element array of this kind structure, existing with transport unit brake tube T
nThis IGCT T during conducting
nThe illuminating part IGCT L that is connected with the control utmost point
nThe example of I-V characteristic be illustrated in the curve map of Figure 11 with solid line 38.Among Figure 11, transverse axis is represented
IElectric current, the longitudinal axis is represented
IVoltage.Because transport unit IGCT T
nConducting, illuminating part IGCT L
nHas the identical linearity I-V characteristic of I-V characteristic with simple diode.Specifically, the about 1V of the diffusion potential of diode, the slope of straight line is equivalent to R
AResistance value (following R
AThe resistance value of also representing itself), be 50 Ω in this figure.On the other hand, illuminating part IGCT L
nRight adjacent IGCT L
N+1The control utmost point because just in conjunction with diode D
nVoltage drop part (about 1V) relate to high voltage thereby
IThe voltage of about 2V just not can conducting on the circuit.If IGCT L
N+1With L
nSimultaneously luminous, then work as
IWhen electric current increases,
IVoltage if surpass IGCT L
N+1Conducting voltage (starting voltage) get final product.At this moment, the I-V characteristic curve then is converted to characteristic shown in the dotted line 39 with the characteristic shown in the solid line 38 from Figure 11.
At R
A=0 o'clock is the situation of circuit among Fig. 3, if ignore the internal resistance of illuminating part IGCT, then the I-V characteristic curve becomes level, so no matter there are much electric currents to flow through, also can not surpass IGCT L
N+1Starting voltage.Here it is before in the self-scanning light-emitting element array each chip a reason that IGCT is luminous can only be arranged.
In the circuit of Figure 10, can be with resistance value R
ABe chosen to, make and flow through 1 electric current in the illuminating part IGCT and can not make adjacent IGCT luminous, and when the electric current that has 2 times flows through wherein, then can make adjacent IGCT also luminous.Specifically, establish and be used for making the luminous of IGCT
IElectric current is I
LThe time, when with V
Th (n+1)Expression IGCT L
N+1Starting voltage and with V
DWhen the pn of table IGCT ties diffusion potential, with respect to
V
D+R
A×I
L<V
th(n+1)<V
D+R
A×2I
L
Separate R
A, obtain
(V
th(n+1)-V
D)/I
L>R
A>(V
th(n+1)-V
D)/2I
L
For example establish V
Th (n+1)=2.1V, I
L=15mA and V
D=1V, then
73.3Ω>R
A>36.7Ω
With this resistance R
AAppend to first in the 3 terminal illuminating part IGCTs of pnpn structure for example shown in Figure 12 A, the 12B.Figure 12 A is a plane, and Figure 12 B is the A-A ' profile of Figure 12 A.
3 terminal illuminating part IGCTs are stacked in turn n type semiconductor chip 41, p type semiconductor layer 42, n type semiconductor layer 43, p type semiconductor layer 44 on n type semiconductor chip 40 basically.On diaphragm 45, be provided with
ICircuit (A1 distribution) 46, to the A1 distribution 48 of the anode 47 of illuminating part IGCT and to the A1 distribution 50 of the control utmost point 49.Resistance R
AForm by being located at the film resistor 51 that the CrSiO cermet on the diaphragm 45 constitutes between A1 distribution 46 and the A1 distribution 48.Though the resistive element has here adopted the CrSiO cermet, also can adopt other cermet (AuSiO, AgSiO etc.), in addition also can be the metallic film of Ni, Cr, NiCr, W, Pt, Pd etc. as resistive element.Have again, on the inboard of n type semiconductor chip 40 shared medial electrode 52 can be set.
Figure 13 A, 13B represent resistance R
AOther configuration example, Figure 13 A is a plane, Figure 13 B is B-B ' the line profile of Figure 13 A.Resistance R in this example
ABe to constitute by the Ni resistive element 53 that inserts between A1 distribution 48 and the anode 47.Also can adopt and aforementioned electric resistance body identical materials at this.
Resistance R
AAlso can by the impurity concentration of regulating anode layer 44 regulate and anode 47 between contact resistance form, in addition, resistance R
AThe dead resistance of illuminating part IGCT realizes in the time of also can be by conducting.
In the example of Figure 13 A-13B, to note being directly connected on the A1 distribution 46 to the A1 distribution 48 of anode 47.Other structure is then identical with Figure 12 A, 12B.
In the light-emitting device array of Figure 10, write signal
IDrive circuit can adopt Fig. 6 or drive circuit shown in Figure 7.
Below with an example of the driving method of the self-scanning light-emitting element array of the drive circuit of Fig. 6 or Fig. 7 explanation Figure 10.It is 1200dpi's that self-scanning light-emitting element array adopts resolution ratio.
This driving method carries out describing of 1200dpi when seeking out high-resolution output, when low the resolution also fully then can be carried out describing of 600dpi when enough, that is be to make adjacent 2 IGCTs side by side luminous in turn.
Figure 14 A and 14B represent respectively with the drive waveforms of the high-resolution of 1200dpi when describing with the low resolution of 600dpi.Make control terminal V among Figure 14 A
IaCorresponding clock pulses 1, 2 get the H level respectively.On the other hand, control terminal V
IbThen still keep the L level.Like this, the illuminating part IGCT of Figure 10 is just luminous in turn one by one.If adopt this driving method, then describe with the resolution ratio of 1200dpi.
In Figure 14 B, control terminal V
Ia, V
Ib2 corresponding continuous respectively clock pulses are got the H level in the identical moment, and thus, 2 adjacent IGCTs are simultaneously luminous in turn.If use this driving method, though be to describe with the resolution ratio of 600dpi since with the driving method of Figure 14 A mutually specific energy make the time for exposure prolong 1 times, thereby can make 1 times of print speed printing speed raising.
The following describes another example of driving method of the self-scanning light-emitting element array of Figure 10.This driving method does not reduce resolution ratio and light exposure is doubled.
In the self-scanning light-emitting element array of Figure 10, at the IGCT T of transport unit
nBe under the state of ON control terminal V
IaDuring for the H level, then the IGCT Ln of illuminating part is luminous.Have again as control terminal V
IaBe under the H level state, with control terminal V
IbWhen becoming the H level, IGCT L then
N+1Also simultaneously luminous.Figure 15 has further represented the exposure status of putting on the photosensitive drums.Point range A among the figure is by using control terminal V
IaGet the H level, the light exposure of the point that causes for luminous IGCT Ln is represented with mark Θ.And by making control terminal V
IbGet the H level, for IGCT L
N+1The light exposure of the point of luminous situation is then represented with the mark Θ of point range B simultaneously.
After 1 row was described, the light exposure of each point had several deciding by the vertical row's of point range A, B mark Θ, and the mark zero in the time of 0 shows does not have exposure, and the mark Θ in the time of 1 represents that light exposure is 1 unit, the mark in the time of 2 ● represent that then light exposure is 2 units (point range C).In view of the above, mark ● front side by side must be that light exposure reduces by half and becomes mark Θ.
Above-mentioned driving method can not reduce resolution ratio and light exposure is doubled.But if adopt this driving method, then describe row front point light exposure for other light exposures partly.But the electrofax mode then can make the more faithful to original image of exposure by the light exposure that suppresses the front.In addition, the light exposure of describing row end point is reduced by half.
According to present embodiment, provide to make the simultaneously luminous self-scanning light-emitting element array of adjacent two illuminating part IGCTs on each chip.Thereby can prolong because of the time for exposure, make light exposure increase on the photosensitive drums, its result improves the print speed printing speed of light printing equipment.
(the 3rd embodiment)
Present embodiment is can make 2 self-scanned light-emitting device array chips that above light-emitting component is simultaneously luminous are arranged on per 1 chip.
First example
The equivalent circuit of the self-scanned light-emitting device array chip of first example as shown in figure 16, this is to be provided with two circuit in 1 chip.It respectively has 6 illuminating part IGCTs to left and right sides circuit 70L, 70R among the figure in order to make drawing simplify illustration.
Each circuit 70L, 70R are identical with circuit shown in Figure 3, and circuit 70L can transmit luminous point from left to right, and circuit 70R can transmit luminous point from right to left.Identical in the element that constitutes each circuit and the circuit shown in Figure 3.In the circuit 70L of left side,
1L, 2
L, refer to clock pulses,
sL refers to start pulse,
IL refers to write signal, and 71L refers to 1L circuit, and 72L refers to 2L circuit, and 73L refers to
1The L circuit.In the circuit 70R of left side,
1R 2R refers to clock pulses,
sR refers to start pulse,
IR refers to write signal, and 71R refers to 1R circuit, and 72R refers to 2R circuit, and 73R refers to
1The R circuit.In addition, also be provided with current-limiting resistance in each circuit.
About this in each circuit, clock pulses 1, 2, start pulse
S, write signal
IDividing other system as each, as shown in the figure, is power supply V
GKFor shared.Shared V
GKLine is indicated with 74.
Figure 17 is the plane of Figure 16 chip practical structures, and Figure 18 is C-C ' the line profile of Figure 17, and the identical parts with Figure 16 among Figure 17 and 18 are attached to be represented with identical label.
Among Figure 17,75,76L, 77L, 78L, 79L and 76R, 77R, 78R, 79R represent the land, 80 expression illuminating parts.
Shown in the profile of Figure 18, self-scanned light-emitting device array chip is made by the pnpn structure.The Pnpn structure shown in Figure 12 B, be on n type semiconductor chip 40 in turn lamination n type semiconductor layer 41, p type semiconductor conductor layer 42, n type semiconductor layer 43 and p type semiconductor layer 44 are arranged.On diaphragm 45, then be provided with 1R circuit 71R, 2R circuit 72R,
ICircuit 73R and V
GKCircuit 74 in addition, also is provided with shared medial electrode 52 in the inboard of n type semiconductor chip.
From Figure 16~18 as can be known, this routine self-scanned light-emitting device array chip is to be taken at the structure of inserting 2 self-scanning light-emitting element arrays on 1 chip.
Under said structure,
I2 was about circuit was divided into
IL line and
IThe R line, every circuit can allow 1 IGCT luminous.Also be that each chip can make 2 IGCTs luminous simultaneously.Therefore can strengthen luminous power, obtain high light output.Though the light-emitting component number of the left and right sides circuit in the last example is identical, and nonessential like this.
Circuit 70L in this example and 70R be respectively from left to right with transmit luminous point from right to left, but not necessarily need get this combining form, in fact be located in the structure at chip two ends in the land, because the start pulse terminal is at the chip two ends, the structure from the chip two ends to center transmission luminous point is easy to make.
Second example
In first example, just simply 2 self-scanning light-emitting element arrays are set up in 1 chip since about have 1 circuit and 2 circuits respectively, land number and chip area are all increased.
For this reason, this example is that 1L circuit 71L is connected in the identical land with 1R circuit 71R, simultaneously 2L circuit 72L also is connected on the identical land with 2R circuit 72R, the structure of Xing Chenging has reduced by two lands than first example thus.
Represented the sort circuit structure among Figure 19. 1L circuit 71L and 1R circuit 71R are connected on 1 bonding land on right side, and 2L circuit 72L and 2R circuit 72R then are connected to the in left side
2In the bonding land.
Figure 20 is the plane of practical structures of the chip of Figure 19, and Figure 21 is D-D ' the line profile of Figure 20.In Figure 20 and 21, for Figure 17 and 18 in identical parts are attached represents with identical label.In addition, 77 expression
1The land, 78 expression
2The land.
Compare with first example and can reduce by 2 land numbers, therefore can reduce chip area.
The 3rd example
First and second example possesses the start pulse terminal is arranged, but by adopting diode to make clock pulses be also used as start pulse, then can omit the start pulse terminal.
Figure 22 has represented the sort circuit structure.Diode 82 is inserted between the control utmost point and 2L circuit 72L of left end transport unit IGCT of left side circuit 70L, simultaneously between the control utmost point and 1R circuit 71R with the left end transport unit IGCT of IGCT 84 insertion right side circuit 70R.
Figure 23 is the plane of Figure 22 chips practical structures, and Figure 24 is E-E ' the line profile of Figure 23.In the circuit of Figure 23 left side 86 and 88 represented the negative electrode and the anode of diode 82 respectively.
According to this routine circuit, owing to omitted
SL land and
SThe R land is so can dwindle chip area.In addition, this routine circuit is jointly luminous point to be transmitted from left to right in left side circuit and right side circuit, but is not having
SIn this structure of land, the illuminating part IGCT owing to freely selecting to start can constitute direction of transfer structure freely.
The 4th example
In second example, the land of 1, 2 can have 1 in per 1 chip, but as shown in figure 19, needs to allow 3 spaces that the clock pulses line passes through on chip surface.Therefore have and make chip area become big problem.For this reason, this example is by being provided with suitable resistance R between the anode of the IGCT of transport unit and clock pulses circuit
B, can on two 1 circuits and 2 circuits, allow 2 IGCTs luminous simultaneously.
Figure 25 has represented this structure, wherein is provided with two , 1 circuit 30, 2 circuits 32, and with transport unit IGCT T
1L, T
2L, T
3L ..., T
1R, T
2R, T
3R ... each anode through resistance R
bBe connected respectively on 1 circuit 30 and 2 circuits 32.Other structures are identical with Figure 16.
Figure 26 is the plane of practical structures of the chip of Figure 25, and Figure 27 is F-F ' the line profile of Figure 26, and among Figure 26,91 refer to 1 land, and 92 refer to 2 lands.
Explanation is by being provided with resistance R now
BCan make the mechanism of adjacent 2 transport unit IGCTs conducting simultaneously.Consider the of Figure 25
sL terminal and
sThe R terminal is in the situation of L level (earth potential).At this moment, transport unit IGCT T
1L, T
1The starting voltage Vth of R is about V
D(diffusion potential of pn knot).Clock pulses 1 becomes the H level, IGCT T
1L, T
1A conducting among the R.The anode of the IGCT of conducting is fixed in about V
DThis moment clock pulses 1 voltage and anode voltage (=V
D) compare to become and be limited to resistance R
BThe high value of voltage drop part.So, before failed the also conducting fast of IGCT of conducting.In other words, IGCT T
1L and T
1R conducting simultaneously.Correspondingly, illuminating part L
1L and L
1R is simultaneously luminous.
At this moment, transport unit IGCT T
2L and T
2The starting voltage V of R
ThAbout 2V
DAfter clock pulses 2 became the H level, either side can both ON.At this moment the I-V characteristic of transport unit IGCT as shown in figure 28.Characteristic when the I-V characteristic shown in the solid line 94 is 1 IGCT conducting is with V=V
D+ R
B* I represents.Characteristic when the I-V characteristic shown in the dotted line 95 is 2 IGCT conductings is with V=V
D+ (R
B/ 2) * I represents.Characteristic when the I-V characteristic shown in the chain-dotted line 9G is 3 IGCT conductings is with V=V
D+ (R
B/ 3) * I represents.
For making I=3mA, selected resistance R
B, R
2Behind clock pulses voltage, the voltage of 2 circuits becomes the starting voltage (=2V than the IGCT of not conducting
D) low value, can only make 1 IGCT luminous.But along with electric current increases, the voltage of 2 circuits raises, and surpasses starting voltage at last, and the I-V characteristic is transferred to 95,2 IGCT T of dotted line from solid line 94
2L and T
2R conducting simultaneously.
Under the said circumstances, resistance R
BBe chosen to be with current-limiting resistance R2 and can make the conducting of 2 transport unit IGCTs but do not make 3 IGCTs conductings simultaneously (when the conducting of the 3rd IGCT betides and transmits).
Specifically, make 2 IGCT conductings when making electric current I flow through 2 circuits, need to satisfy
V
Th<V
D+ R
B* I and, then need satisfying in order not make 3 above IGCT conductings
V
Th>V
D+ (R
B/ 2) * I solves I to above two formulas, has
2 (V
Th-V
D)+R
B>I>(V
Th-V
D)/R
BThis I is by the H level voltage V of clock pulses
HDetermine with resistance R 2:
I=(V
Th-V
DThese relational expressions of)+R2 are also set up in the situation that electric current I flows through in 1 circuit.
Consider that the relation of these formulas and the condition of work of IGCT determine R
BValue with R1, R2.At the I-V of Figure 28 characteristic situation, R
BDuring=375 Ω, become 411 Ω<R1, R2<800 Ω.
Form resistance R
BThe time several different methods is arranged, be to set the impurity concentration of anode layer epitaxial film lowly here, regulate to increase between anode and the anode layer contact resistance and as resistance R
B
Resistance R
BAlso available additive method forms, and resistive layer etc. for example can be set between anode and metal wiring also or make independently with semiconductor and metallic film etc. that resistance is connected.
The 5th example
It in the structure of first~the 4th example expression side (referring to Figure 17, Figure 20, Figure 23 and Figure 26) that 1 circuit is arranged at illuminating part IGCT row.But when the bigger light exposure of needs, 1 circuit can be divided into two both sides that are divided into the illuminating part IGCT, can make each chip can make 4 illuminating part IGCTs simultaneously luminous thus.
Figure 29 has represented the sort circuit structure and Figure 30 has represented the practical structures of chip, and this example is with in the structure of first example (Figure 16, Figure 17)
I Circuit 73L,
I R circuit 73R is divided into 2 example respectively.
Make 2 illuminating part IGCTs corresponding to 1 transport unit IGCT, make illuminating part IGCT and 2 among the circuit 70L of left side
IL circuit 73L (1) and
IL circuit 73L (2) connects respectively alternately; Make illuminating part IGCT and 2 among the circuit 70R of left side
IR circuit 73R (1) and
I R circuit 73R (2) connects respectively alternately.
In addition, in Figure 30, the of circuit 70L on the left of 79L (1) represents respectively with 79L (2)
IL1,
IThe land of L2 circuit; 79R (1), 79R (L) represent the of right side circuit 70R respectively
IR1,
IThe land of R2 circuit.
Under this structure, 2 IGCTs that can make 2 IGCTs at circuit 70L place, left side and circuit 70R place, right side totally 4 whiles luminous.
Make above-mentioned 4 such IGCTs simultaneously luminous structures also can be applicable to second, third and the 4th example.
(the 4th embodiment)
Present embodiment is with the driving method of the self-scanning light-emitting element array of 3.3V power-supply system driving diode combination and the drive circuit of realizing this driving method.
The operating voltage minimum of a value of the box-like self-scanning light-emitting element array of diode junction shown in Figure 3 is by the conducting voltage V decision of transport unit IGCT.IGCT T
nIGCT T under conducting state
N+1Conducting voltage V
t, be similar to control pole tension V as described above
GPn knot diffusion potential V between the+control utmost point and anode
D
More exactly, the conducting voltage of IGCT can be expressed as
V
t=V
G+ V
D+ Rp * I
ThRp in the formula is control utmost point dead resistance, I
ThBe threshold current.Control pole tension V
GCan be expressed as
V in the formula
GONBe the IGCT T of conducting
nThe control pole tension.When in IGCT is made, having adopted the material of GaAs system, V is arranged then
D=1.2V, V
GON=0.3V, I
Th=10 μ A, and V
t=2.8V.
For making IGCT T
N+1Conducting needs to make IGCT T in IGCT conduction period
N+1Anode voltage surpass conducting voltage V
tTo this IGCT T
N+1The 1 or 2 line chargings that connect are as IGCT T
N+1Time that can conducting, reach t overlapping time of H level simultaneously by clock pulses 1, 2
aDecision.
If 1 is C with the electric capacity of 2 circuits
1, C
2, the current-limiting resistance value is R
1, R
2, the 1 line voltage distribution V1 of t after second became when then 1 circuit became the H level
V1=V
HIn (1-exp (t/R1 * C1)) formula, V
HVoltage for the H level.Also be t overlapping time
aBecome the value that satisfies the following formula scope:
V
t<V
H(1-exp (t
a/ R1 * C1)) and for 2 circuits, identical with following formula, V is arranged
t<V
H(1-exp (t
a/ R2 * C2))
At this overlapping time t
aIn, the illuminating part IGCT can not conducting, thereby works as t
aAfter the increase, may luminous time scale reduce.
When using the power supply of 3.3V system, imagination can produce ± 100% voltage pulsation approximately, then must guarantee minimumly to work with 3.0V.When driving,, must increase t overlapping time in order to be charged to 2.8V with supply voltage 3.0V
a
In order to shorten this overlapping time of t
aThough, can reduce current-limiting resistance R1, the R2 of clock pulses 1, 2, if it is reduced, the electric current of the IGCT of then flowing through after the conducting strengthens, and power consumption is increased.
Even be the value that reduces resistance R 1, R2, but overlapping time t
aCan reduce to the limit because of other reasons, these reasons are as follows.Specifically, for the conducting IGCT, the pn knot between the control utmost point and anode needs by suitable direction biasing.Consider at IGCT T now
2nUnder the conducting state, for making IGCT T
2n+1Conducting and make clock pulses 1 be the situation of H level.When clock arteries and veins 1 is the L level, IGCT T
2n+1Control pole tension V
GBecome than anode voltage V
GHigh voltage.So the pn between the control utmost point and anode forms for anti-inclined to one side.The capacitor C of certain electric charge can stored
pIn see.This electric capacity is in order to pass through dead resistance R
pCharge/discharge roughly has R
p* C
pTime constant, therefore at R
p* C
pAmong<R1 * C1, R
p* C
pTime constant determine charge/discharge speed.
According to the driving method of present embodiment, by to be no more than conducting voltage V
tVoltage give the clock pulses line charging in advance, even when using, also can shorten t overlapping time with low supply voltage
aSo with transport unit IGCT T
2nMake IGCT T after the conducting
2n+1During conducting, overlapping time t
aThe time variation that fully increases 1 line voltage distribution under the situation is shown among Figure 31, and curve 101 shows that the time of 1 line voltage distribution when being precharged to 2V changes the time variation of 1 line voltage distribution when curve 102 shows not precharge.
In the situation that 1 circuit is pre-charged to 2V, the about 25ns conducting of IGCT then needs 55ns just to begin conducting when precharge not.Overlapping time t
aOwing to can overlap onto on this ON time, so can shorten.
For the self-scanning light-emitting element array of the diode junction mould assembly of Fig. 3, studied at supply voltage V
GKDuring for 3V, current-limiting resistance R1, pre-charge voltage (1V, 2V, 2.5V) and transmit in required overlapping time t
aThe relation of minimum of a value, its result is illustrated among Figure 32.When not precharge (0V), even make R1 little to 100 Ω, t
aAlso only can be little to about 40ns.But to the precharge of having carried out 2.5V, even R1 is 500 Ω, also can be little to about 10ns.
Though being chosen as pre-charge voltage than conducting voltage at this is low value, because influences such as noise, for making unlikely conducting mistakenly; Preferably make pre-charge voltage than conducting voltage low value surpass 0.2V.
First example
Figure 33 illustration the drive circuit of Fig. 3 diode in conjunction with self-scanning light-emitting element array.Represent self-scanned light-emitting device array chip 110 and drive circuit 112 among Figure 33, on chip 110, represented 1, 2, V
GK,
s,
IThe land.
According to this drive circuit 112, two kinds of power supply Vp1 (3.3V) and power supply Vp2 (2.5V) have been prepared.At relevant start pulse
sWith write signal
IFormation in, adopted the inverter buffer 160 of CMOS.Inverter buffer 160 is made up of with N-channel MOS FET162 p channel mosfet 161, and the drain electrode of p channel mosfet 161 connects power supply V
p1, the source ground of N-channel MOS FET162.The control utmost point of these two MOSFET is connected on the control signal terminal 120,140 simultaneously.The tie point of the drain electrode of the source electrode of P channel mosfet 161 and N-channel MOS FET162 is by current-limiting resistance R
s with chip 110
sThe land links to each other.
In the formation of relevant clock pulses 1, 2, used the circuit 170 that 3 analog switches 171,172 and 173 of band control terminal are combined into.When adopting control terminal to be the H level, analog switch 171,172 and 173 connects the type that disconnects during for the L level.One end of switch 172,173 respectively with power supply V
p2, power supply V
p1 connects, and their other end then jointly is connected on the end and switch 110 1 land of switch 171 by current-limiting resistance R1, and the other end of switch 171 is ground connection then.Each control terminal of switch 171,172,173 is connected with terminal 130,131,132 and terminal 150,151,152 respectively.
The I/O waveform of this drive circuit as shown in figure 34.The waveform on the top of Figure 34 represents to offer the of chip 110
s, 1, 2,
IWaveform, the waveform V (120) of Figure 34 bottom, V (130) ... it is each terminal 120,130 of drive circuit 112 ... the input waveform of middle control signal.
Start pulse
sAs control voltage V (120) when becoming the H level, FET161 disconnects and the FET162 conducting is reduced to 0V from 3.3V, and the transport unit IGCT then will be by clock pulses 1 conducting.Start pulse
sWhen descending, clock pulses 1 returns 3.3V. simultaneously
The level of control voltage V (130), V (131), V (132) is by illustrated this variation, switch 171,173 is disconnected and connection switch 172, allow 1 circuit be pre-charged to 2.5V from 0V, cut-off switch 172 then, connect switch 171, make 1 circuit rise to 3.3V.
Time t
aThe time that the clock pulses 1 of expression 3.3V and the clock pulses of 3.3V 2 are overlapping, time t
bExpression clock pulses 1, 2 drop to write signal respectively
IThe time of rising, time t
eBecome time of OV respectively Deng expression clock pulses 1, 2, and T represents write signal
ICycle.Time t
bIt is the required time of influence that is used to eliminate before luminous illuminating part IGCT.
Because 1, 2 circuits are pre-charged to 2.5V, as indicated in Figure 31, it is very short that the voltage of these two circuits rises to the time of 3.3V, thereby can shorten t overlapping time in this example
a
This example has been confirmed t
a=30ns, t
b=10ns, t
e=100ns, the operation of T=250ns.
Second example
Though in first example, prepared two kinds of power supplys of 3.3V and 2.5V, preferably used 3.3V power supply.Here be provided with the buffer circuit of the level shifter of diode composition in the driving of clock pulses 1, 2, adopting.This circuit is shown among Figure 35.Figure 35 has represented chip 110 and drive circuit 114, is illustrated in 1, 2, V in the chip 110
GK,
s,
IThe land.
Be provided with the anti-phase buffer circuit of level shifter among the figure 180 refers to, this circuit comprises the p channel mosfet 183 of level shifter that 2 grades of diodes 181,182 form, series connection with it and N-channel MOS FET184, the level shifter p channel mosfet 185 in parallel with the series circuit of p channel mosfet 183 herewith.The source electrode of the anode of diode 181 and p channel mosfet 185 is with power supply V
p(3.3V) connect.The control utmost point of P channel mosfet 183,185 is connection control signal terminal 133,134 and 153,154 respectively.
Be about 0.6V owing to constitute each level of diode 181,182 voltage drops that caused of level shifter, thereby the 1.2V that in 2 grades, descends approximately.In other words, when power supply was 3.3V, the voltage by the diode level shifter became 2.1V.
The I/O waveform table of drive circuit is shown among Figure 36.In the situation of the anti-phase buffer circuit 180 that adopts clock pulses 1 usefulness, when being the H level, establishes voltage V (134) control voltage V (133) for behind the H level owing to control, and FET 183 disconnects and FET 184 conductings.Thereby become OV and establish control voltage V (133) for behind the L level when 1 circuit, FET183 conducting and FET 184 disconnects is so 1 circuit becomes 2.1V.If make control voltage V (134) get L level FET 185 just conductings, 1 circuit becomes 3.3V.
Why electing diode progression as 2 grades at this, is to be no more than conducting voltage V for the voltage make level shifter when supply voltage fluctuates in 3.0~3.6V scope after
t(=2.8V)
The 3rd example
In first and second example, be to drive with voltage signal to drive circuit.Then the circuit that drives clock pulses 1, 2 usefulness with current signal in this example.This drive circuit is illustrated among Figure 37.Drive circuit as clock pulses 1, 2 usefulness adopts in parallel with the current source 191 (0.2mA) and the current source 192 (1mA) of band control terminal.
The control terminal of current source 191 is connected with control signal terminal 133,135 respectively, and the control terminal of current source 192 then is connected with control signal terminal 136,156 respectively.This current source 191,192 is when control terminal is the H level, and the electric current that flows through setting respectively is as 200 μ A, 1mA, if during for the L level then no current flow through.Figure 38 represents the I/O waveform of drive circuit.
According to the I-V characteristic of IGCT shown in Figure 39, the anode voltage of the transport unit IGCT when voltage V (135) and V (155) have the electric current of 200 μ A to flow through for the H level is about 2.5V, under this state, and IGCT not conducting fully.Therefore the illuminating part IGCT that is connected with this transport unit IGCT is not luminous.Then, making voltage V (136) and V (156) is the H level, the made transport unit IGCT conducting of flowing through at the electric current that 1.0mA is arranged, thus can make the illuminating part IGCT luminous.Under this mode, obtain and the identical result of situation with 2.5V precharge 1, 2 circuits.
The 4th example
Under first and second routine drive waveforms,, apply 3.3V usually in order to keep the conducting state of transport unit IGCT.But the conducting state of IGCT is if just can fully keep can have the above electric current of maintenance electric current (being about 400 μ A under the I-V characteristic of Figure 39) to flow through the time.For this reason, in t
aAfter time, as long as make current value keep just keeping conducting fully on the electric current.So in first and second routine circuit, only need the control signal of change drive circuit, just can make t
a 1 after time, the voltage of 2 descend and reduce power consumption.
Use the drive circuit of first example, drive with the control signal of the waveform of Figure 40.By the waveform of illustrated V (130), V (131), V (132) and V (150), V (151), V (152), can obtain the waveform of illustrated 1, 2.With the waveform of 1, the 2 of Figure 34 more as can be known, the duration of 3.3V has shortened.
The about 1.6V of voltage of 1, 2 circuits during the conducting of transport unit IGCT.So the electric current when being about the situation transport unit IGCT conducting of 500 Ω for the value of current-limiting resistance R1, R2 is 3.4mA down in 3.3V, is 1.8mA when 2.5V, diminishes owing to flow through the current value of IGCT, the power consumption of transport unit can reduce by half.
Equally, the circuit of using second example can shorten the duration of 3.3V, in this case, the consumed power of transport unit is reduced by half.
According to this method of present embodiment, can realize dwindling t overlapping time with the self-scanning light-emitting element array of 3.3V power-supply system driving diode combination
aDriving method, and then can provide the drive circuit of realizing this driving method.
In addition, in above embodiment, clock pulses is with respect to the explanation of 2 phase situations, but obviously present embodiment can be not limited to 2 phase situations, also can be applicable to the self-scanning light-emitting element array of the clock pulses that adopts m (m is 2 above integers) phase.
(the 5th embodiment)
Present embodiment is when light-emitting device array is lined up stagger mode formation light-emitting device array, to be used for being implemented in the chip junction and not produce the light pen of printing striped and be used to realize the rod lens array of this light pen and the collocation method of light-emitting device array.
Version with a plurality of chip alinement shapes is arranged in self-scanning light-emitting element array.Shown in Figure 41 A, make die terminals dock the shape that is arranged in a straight line a plurality of chips 200.In die terminals, the arrangement pitch of light-emitting component 202 is non-constant.For fear of this situation, shown in Figure 41 B, make the part of cake sheet end overlapping, be arranged in so-called stagger mode, at the tie point of chip, the arrangement pitch of light-emitting component is constant.Here so-called tie point is meant place, the chip end light-emitting component foremost and place, the light-emitting device array chip end light-emitting component foremost of opposite side of the light-emitting device array chip of a side, arranges pitch part arranged side by side by 1.Among Figure 41 B the coupling part is surrounded with dotted line 204.
Light-emitting device array has with light-emitting component itself lines up the light-emitting device array that stagger mode is got two array structures.This light-emitting device array can be in the hope of the resolution multiplied resolution ratio of each row light-emitting component.
When the light pen of forming with this light-emitting device array prints, because the structure of rod lens array and the tie point place that is arranged in chip chamber of rod lens array and light-emitting device array, or light-emitting component longitudinally between the adjacent light-emitting component, produces sometimes and prints striped between row and row when lining up the light-emitting device array of stagger mode by 2 row.
The following describes its reason.Figure 42 represents with rod lens 206 by the above-listed and following line that is stacked into the rod lens arrays 209 of two row, is linked to be along the lens arrangement direction with above-listed and following rod lens tie point 208 in Figure 42 as X-axis, and from following the tie point 210 of 2 adjacent rod lens towards X-axis along line that vertical line drew as Y-axis.
In addition, though expression in Figure 42, this rod lens array is that with rod lens rule and strictly precision is arranged in and forms between two backplates, in the gap of rod lens for removing the filling that glares with black resin.
If the diameter of rod lens is D, length is Z, and conjugate length (distances between object and image planes) is TC, and operating distance (distance from lensed endface to the object image-forming face) is Lo, and the refractive index on the lens axis is N.And 2 index distribution constants are g, and at this moment, each rod lens under wavelength 740nm, is established D=0.563mm, Tc=9.1mm, Z=4.45mm, Lo=2.33mm, No=1.627, g=0.843mm
-1
For this rod lens array, in the scope of the position of X-direction shown in Figure 42 A and B, the light quantity variation with regard to Y direction position y=0mm, 0.05mm and three kinds of situations calculating of 0.10mm X-direction is illustrated respectively in Figure 43 A, 43B, 43C with accordingly result.Among each figure, A represents the position of X=0, and B represents the position that equates with the radius of rod lens on the X-direction.A, B position generally are the above-listed and following contacted positions of rod lens among each at rod lens array.Can see that from these figure along with departing from the y direction of principal axis, the light quantity difference of A, B position increases, when y=0.10mm, have an appointment 10% poor.
With respect to this rod lens array 209, light-emitting device array chip is lined up 2 row by stagger mode, the light-emitting component of one side's chip is arranged corresponding to the y axle of Figure 42, the y place, position that the opposing party's chip light emitting arrangements of components is departed from out 0.10mm on the y direction of principal axis, when the tie point of chip arrived A or B position, light quantity was done discontinuous variation by 10% part.
Calculate according to same viewpoint, under wavelength 780nm, with respect to D=0.88mm, TC=15.3mm, Z=6.93mm, Lo=4.20mm, N
O=1.625, g=0.531mm
-1, h
4=0.8, h
6=-3.112, h
8The result that the MTF of=9.205 rod lens array (spatial frequency 24Lp/mm) carries out is illustrated respectively in Figure 44 A, Figure 44 B and Figure 44 C.
Figure 44 A, 44B, 44C represented the skew (Δ TC) of TC be respectively Δ TC=0mm ,-0.1mm ,+during 0.1mm, in the value of y direction of principal axis position y=0mm, 0.05mm, 0.10mm.
h
4, h
6, h
8Be high order index distribution constant.MTF (modulation transfer function) is the image quality evaluation index of the image transmission characteristic of expression rod lens array, can be obtained by following formula
I in the formula (W) max and i (W) min are respectively the maximum and the minimum of the response of spatial frequency W (Lp/mm).MTF is more near 100%, and resolution ratio is just bigger, has also promptly formed real in the picture of former figure.
From Figure 44 A, 44B, 44C as can be known, when rod type lens array is used for best TC position (MTF becomes maximum TC), basically be unquestioned, but in actual applications, even the TC skew for it is believed that about 0.1mm that can not avoid also can have a significant impact with respect to " MTF changes due to the y direction of principal axis position ", in the situation of y=0.10mm, MTF in A, B position is poor, also can be near 20%.As hereinbefore, when the tie point that is arranged in zigzag light-emitting device array chip is in the position of A or B, discontinuous variation takes place.
Figure 45 represents that diameter D is the rod lens array 212 of the rod lens 206 of 0.75mm by two row stacked arrangement one-tenth, with with light-emitting component (light emitting diode for example, luminous IGCT) presses 1200dpi, the self-scanned light-emitting device array chip 214 that 256 light-emitting components (effective length 5.4mm) assortment becomes is arranged into the relation of the light-emitting device array of stagger mode, in Figure 45,216 and 218 expression backplates, 220 expression black resins, the tie point of self-scanned light-emitting device array chip partly is in the contact position place of the above-listed middle rod lens of the rod lens array shown in the arrow C.Like this, when the tie point of light-emitting device array chip was partly come the C position of rod lens array, in the tie point part, the discontinuous variation by light quantity and MTF can produce striped during printing.
Figure 46 represents that diameter D is that the rod lens 206 of 0.6mm is by 2 row stacked arrangement rod lens 212 that becomes and the configuration relation of light-emitting component 222 being got the light-emitting device array 224 of stagger mode arrangement by two row.Rod lens array above-listed or following in the contacted position D of adjacent rod lens, E, F place, in the local time that neighbouring light-emitting component arrives these, identically with Figure 45 can produce the printing striped.
In order not produce this printing striped, key is which type of structure rod lens array gets.Claim now rod lens array perpendicular to its longitudinally direction be its thickness direction, then need make rod lens array get geometric line symmetrical structure along thickness direction; Or get a plurality of rod lens stacked arrangement are become two groups, and allow this first and second group lens arra become overlapping close contacting structure.
For above-mentioned preceding a kind of rod lens array, light-emitting device array chip or light-emitting component can be arranged with respect to get stagger mode by antimeric 2 lines of the line of rod lens array.By means of this arrangement form, because the line symmetry on the geometry of this rod lens array, even light-emitting element chip or light-emitting component are arranged to stagger mode, the situation equivalence that can form a line with light-emitting component when rod lens is observed.Thereby between the tie point of light-emitting device array chip part or the adjacent light-emitting component wherein, discontinuous variation can not take place in light quantity and MTF yet.
To a kind of rod lens array in last aforesaid back, can be with light-emitting device array chip or light-emitting component along first lens arra, second center line of first center line and second lens arra longitudinally, or the interval of former state ground maintenance first center line and second center line, by thickness direction translation, be arranged to stagger mode with respect to formed 2 lines along rod lens array.Compare the two parts that disposed, for the situation that does not have degree of overlapping from the opposing party's light basically, can be regarded as equal position mutually, even thereby light-emitting device array chip or light-emitting component are arranged to stagger mode, when rod lens array is observed, with the light-emitting component situation equivalence that forms a line.In addition, above-mentioned degree of overlapping is arranged the ratio Xo/Do definition of cycle Do with respect to rod lens by the radius of view Xo of rod lens imaging.
First example
Figure 47 represents to dispose with respect to the rod lens array 226 that rod lens 206 becomes with odd column (illustration 3 row among the figure) lamination the example of self-scanned light-emitting device array chips 214.Rod lens array 226 becomes how much line symmetry with respect to the axle 230 of the longitudinal centre line that is equivalent to central array.With respect to symmetry axis 230, subtend is made chiasmus by becoming antimeric 2 lines 242,234 of line with self-scanned light-emitting device array chip 214 then.
According to the structure of above-mentioned this rod lens array and with respect to the layout of the light-emitting device array chip of rod lens array, just can partly avoid discontinuous big light quantity and the variation of MTF at the tie point of light-emitting device array chip.
Second example
Figure 48 is identical with Figure 47, illustration with respect to the stacked rod lens array 226 of 3 row, the light-emitting device array 240 that the light-emitting component chiasmus is constituted.In this example, by antimeric 2 lines 232,234 of line, light-emitting component 242a, 242b are pressed stagger mode arrange with respect to symmetry axis 230, subtend.
Arrange according to the structure of this rod lens array and with respect to the light-emitting component of rod lens array, just can between adjacent 2 light-emitting component 242a, 242b, avoid discontinuous big light quantity and variation MTF.
The 3rd example
Figure 49 illustration the rod lens array 244 (being 2 row in the illustrated example) that becomes by the square arrangement lamination with rod lens 206, and disposed self-scanned light-emitting device array chip 214 therewith relatively.The pros here arrange and pile up, and as shown in figure 49, can be described as the overlapping method that respectively is centered close to foursquare each summit by 4 adjacent up and down rod lens 206.According to this kind overlapping method, rod lens array becomes how much line symmetry with respect to symmetry axis.Then, with respect to symmetry axis 230, subtend is pressed stagger mode with self-scanned light-emitting device array chip 214 and is arranged by 2 lines 232,234 of the part of line symmetry.
According to the structure of above-mentioned rod lens and with respect to the layout of the self-scanned light-emitting device array chip of rod lens, can avoid in the discontinuous big light quantity at the tie point place of chip and the variation of MTF.
The 4th example
Figure 50 is identical with Figure 48, illustration the array 244 of the rod lens that becomes with respect to 2 row square arrangement laminations, the light-emitting device array 240 that light-emitting component is staggered and becomes 2 row and constitute.One with respect to symmetry axle 230 not in this example, and subtend is arranged in stagger mode with light-emitting component 242a, 242b by antimeric 2 lines 232,234 of line.
According to above-mentioned rod lens array structure and with respect to the layout of the light-emitting component of rod lens array, can avoid that discontinuous big light quantity and the variation of MTF are arranged between adjacent 2 light-emitting component 242a, 242b.
The 5th example
In above 4 examples, all adopted the rod lens array that becomes the geometrical line symmetry along thickness direction.Even yet adopt along how much asymmetric rod lens arrays as described below of thickness direction, also can obtain same effect.
Figure 51 represents to get the rod lens array 254 of overlapping close contact structures by rod lens 206 by stacked 2 lens arras 250,252 that constitute of 2 row.The longitudinal centre line of each lens arra 250,252 is with 256,258 expressions, and the longitudinal centre line of rod lens array 254 is with 260 expressions.
This rod lens array 254 of subtend is staggered the center line 256,258 of self-scanned light-emitting device array chip 214 relative each lens arra 250,252.Arranged light-emitting device array chip in this wise, just can with press linearity with respect to rod lens 254 and arrange the situation equivalence of chip.Thereby,, can avoid the variation of discontinuous big light quantity and MTF for the end of a square chip and the end of the opposing party's chip at the tie point place of chip.
In addition, the interval of center line 256 and 258 is remained unchanged light-emitting element chip is staggered, also can try to achieve identical effect with respect to 2 lines that form by thickness direction translation along rod lens array 254.
The 6th example
Figure 52 is routine identical with Figure 51's, has represented with respect to the stacked rod lens array 254 of 4 row, and subtend center line 256,258 is arranged in stagger mode with light-emitting component 242a, 242b and the light-emitting device array 240 that constitutes.According to the structure of this rod lens array and light-emitting component layout, can avoid between 2 light-emitting component 242a, 242b of adjacency, having discontinuous big light quantity and variation MTF with respect to rod lens array.
In addition, keep the interval of center line 256 and 258 constant, light-emitting component is staggered, also can obtain identical effect with respect to 2 lines that form by thickness direction translation along rod lens array 254.
According to present embodiment, light-emitting device array is lined up the light pen of stagger mode, or 2 row light-emitting components are arranged to the light pen of stagger mode with the structure that obtains resolution ratio and double for each column split rate, wherein because tie point/longitudinally adjacent luminous element position place between light-emitting device array chip does not have the variation of discontinuous light quantity and resolution ratio, thereby can provide the tie point/longitudinally adjacent luminous element position place between light-emitting device array chip to be difficult for taking place to print the light pen of striped.
The driving method of self-scanning light-emitting element array of the present invention, self-scanning light-emitting element array and drive circuit can be applied in the light pen of light printing and can realize high-precision light pen.