What is claimed is:
1. A spark-ignition engine controller used for a multi-cylinder spark-ignition engine performing a four cycle consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke at a predetermined phase difference in each cylinder, wherein a gas flow path is formed into a state of two-cylinder connection where, in at least a low-load low-speed range, determined by an operation condition identifier, burned gas discharged from a preceding cylinder, which is a cylinder in the exhaust stroke, of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced into a following cylinder, which is a cylinder in the intake stroke, through an intercylinder gas channel, and exhaust gas discharged from the following cylinder is led to an exhaust passage; said spark-ignition engine controller comprising:
the operation condition identifier for determining an engine operation condition based on an engine speed and an engine load;
an intake air quantity control means for controlling an amount of an air to be supplied to the preceding cylinder in such a manner that the airfuel ratio based on the amount of fuel required to both of said preceding and the following cylinders becomes a stoichiometric air-fuel ratio in said both cylinders in the state of two-cylinder connection; and
a combustion controller including:
an fuel injection means for injecting fuel at a certain timing in which an amount of fuel injected to both of said preceding and following cylinders is determined in accordance with a required torque in the state of two-cylinder connection; and
an ignition controller for controlling an ignition timing;
said combustion controller which, during said two-cylinder connection, causes combustion to be performed in said preceding cylinder at an air-fuel ratio which is leaner than the stoichiometric air-fuel ratio by a predetermined amount, and causes combustion in said following cylinder at a predetermined air-fuel ratio by feeding fuel to the lean air-fuel ratio burned gas introduced from said preceding cylinder,
said combustion controller performing control such that, in at least a part of an operating range in which said two-cylinder connection is set, combustion is performed in said following cylinder through compression ignition, and
said combustion controller controlling, in a low-load region among said operating range in which the two-cylinder connection is set, said injection controller and said ignition controller such that an air-fuel ratio of the preceding cylinder is set such that an excess air ratio of the preceding cylinder becomes three or greater than three and a combustion is performed in the following cylinder by spark ignition at an air-fuel ratio being equal to a stoichiometric air-fuel ratio.
2. The spark-ignition engine controller according to claim 1, wherein, a fuel amount injected to said both cylinders consisting of said preceding cylinder and said following cylinder is set such that a supplied fuel amount to the preceding cylinder is or less than and a supplied fuel amount to the following cylinder is or more than against the total amount of the fuel injected to said both cylinders and at this time stratified charge combustion is performed in the preceding cylinder in a low load operation range within the operation range where the two-cylinder connection is set.
3. The spark-ignition engine controller according to claim 1, wherein, in the low-load range within the operating range in which said two-cylinder connection is set, the ratio of the fuel injection quantity in said preceding cylinder is set to increase as the engine load increases.
4. The spark-ignition engine controller according to claim 1, wherein, in the low-load range within the operating range in which said two-cylinder connection is set, the fuel is injected to the preceding cylinder in compression stroke and the fuel is injected to the following cylinder in expansion stroke.
5. A multi-cylinder spark-ignition engine comprising:
cylinders, each of which performs 4 cycles, consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke at a predetermined phase difference in each cylinder;
a gas flow path which is formed into a state of two-cylinder connection: including an intercylinder gas channel and an exhaust passage such that, in at least a low-load low-speed range, determined by an operation condition identifier, burned gas discharged from a preceding cylinder, which is a cylinder in the exhaust stroke, of a pair of cylinders having an overlapping exhaust stroke and intake stroke is introduced into a following cylinder, which is a cylinder on the intake stroke side, through said intercylinder gas channel, and exhaust gas discharged from the following cylinder is led to said exhaust passage;
a spark-ignition engine controller including:
the operation condition identifier for determining an engine operation condition based on an engine speed and an engine load;
an intake air quantity control means for controlling an amount of an air to be supplied to the preceding cylinder in such a manner that the airfuel ratio based on the amount of fuel required to both of said preceding and the following cylinders becomes a stoichiometric air-fuel ratio in said both cylinders in the two-cylinder connection state; and
a combustion controller including:
an fuel injection means for injecting fuel at a certain timing in which an amount of fuel injected to both of said preceding and following cylinders is determined in accordance with a required torque in the state of two-cylinder connection; and
an ignition controller for controlling an ignition timing;
said combustion controller which, during said two-cylinder connection, causes combustion to be performed in said preceding cylinder at an air-fuel ratio which is leaner than the stoichiometric air-fuel ratio by a predetermined amount, and causes combustion in said following cylinder at a predetermined air-fuel ratio by feeding fuel to the lean air-fuel ratio burned gas introduced from said preceding cylinder,
said combustion controller performing control such that, in at least apart of an operating range in which said two-cylinder connection is set, combustion is performed in said following cylinder through compression ignition, and
said combustion controller controlling, in a low-load region among said operating range in which the two-cylinder connection is set, said injection controller and said ignition controller such that an air-fuel ratio of the preceding cylinder is set such that an excess air ratio of the preceding cylinder becomes three or greater than three and a combustion is performed in the following cylinder by spark ignition at an air-fuel ratio being equal to a stoichiometric air-fuel ratio.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An optical pointing device comprising:
a light source configured to respond to a drive current to provide at least partially coherent light to illuminate an imaging surface to thereby generate reflected images; and
a navigation sensor configured to generate digital images based on the reflected images, and generate movement data based on the digital images that is indicative of relative motion between the imaging surface and the optical pointing device;
a light source driver configured to provide the drive current to the light source; and
a drive current controller configured to control the light source driver and calibrate the drive current based on selected digital images.
2. The optical pointing device of claim 1 wherein the light source comprises a laser.
3. The optical pointing device of claim 1 wherein the light source comprises a vertical cavity surface emitting laser (VCSEL).
4. The optical pointing device of claim 1 wherein the light source comprises a broadband light source configured to provide broadband light, and a narrow band filter configured to filter the broadband light to provide the at least partially coherent light.
5. The optical pointing device of claim 1 wherein the navigation sensor is configured to capture frames of the digital images at a frame rate, and pulse the drive current at a duty cycle that is synchronized to the frame rate.
6. The optical pointing device of claim 1 wherein the navigation sensor is configured to reduce the drive current during an operating mode if the digital images generated based on the reflected images are saturating the navigation sensor.
7. The optical pointing device of claim 1 wherein the navigation sensor is configured to calibrate the drive current after a reset condition occurs in the navigation sensor.
8. The optical pointing device of claim 7 wherein the navigation sensor is configured to repetitively cycle through available drive current values until one of the drive current values produces a suitable quality digital image based on the reflected image.
9. The optical pointing device of claim 8 wherein the navigation sensor is configured to determine whether a digital image is a suitable quality digital image based on at least one of a navigation suitability measurement derived from the digital image, a measured average pixel value of the digital image, a measured minimum pixel value of the digital image, a measured pixel ratio value of the digital image, and a measured maximum pixel value of the digital image.
10. The optical pointing device of claim 1 wherein the navigation sensor is configured to calibrate the drive current after a selected rest period that the optical pointing device has been at rest.
11. The optical pointing device of claim 10 wherein the selected rest period is selected to avoid disrupting a user of the optical pointing device.
12. The optical pointing device of claim 10 wherein the navigation sensor is configured to cycle once through available drive current values until one of the drive current values produces a suitable quality digital image based on the reflected image.
13. The optical pointing device of claim 12 wherein the navigation sensor is configured to set the drive current value to a previous drive current value taken from when the calibration started after the selected rest period if none of the available drive current values produces a suitable quality digital image based on the reflected image.
14. The optical pointing device of claim 12 wherein the navigation sensor is configured to determine whether a digital image is a suitable quality digital image based on at least one of a navigation suitability measurement derived from the digital image, a measured average pixel value of the digital image, a measured minimum pixel value of the digital image, a measured pixel ratio value of the digital image, and a measured maximum pixel value of the digital image.
15. The optical pointing device of claim 10 wherein the navigation sensor is configured to cycle through a selected number of drive current values until one of the drive current values produces a suitable quality digital image based on the reflected image, wherein the selected number is less than all of the available drive current values.
16. The optical pointing device of claim 15 wherein the navigation sensor is configured to set the drive current value to a previous drive current value taken from when the calibration started after the selected rest period if none of the selected number of drive current values produces a suitable quality digital image based on the reflected image.
17. The optical pointing device of claim 15 wherein the navigation sensor is configured to determine whether a digital image is a suitable quality digital image based on at least one of a navigation suitability measurement derived from the digital image, a measured average pixel value of the digital image, a measured minimum pixel value of the digital image, a measured pixel ratio value of the digital image, and a measured maximum pixel value of the digital image.
18. The optical pointing device of claim 1 wherein the navigation sensor includes at least one of the light source driver and the drive current controller.
19. The optical pointing device of claim 1 wherein at least one of the light source driver and the drive current controller is external to the navigation sensor.
20. A method of operating an optical pointing device, the method comprising:
providing a drive current to a light source;
illuminating an imaging surface with at least partially coherent light from the light source in response to the drive current, thereby generating reflected images;
generating digital images based on the reflected images;
generating movement data based on the digital images; and
calibrating the drive current based on selected digital images.
21. A navigation sensor for generating movement data to control the position of a screen pointer, the navigation sensor comprising:
a light source driver configured to provide a drive current;
a sensor array configured to sense reflected images from an imaging surface produced by an at least partially coherent light source in response to the drive current;
an analog to digital converter configured to generate digital images based on outputs of the sensor array; and
a processor configured to generate movement data based on the digital images, provide a desired drive current value to the light source driver, and calibrate the drive current based on selected digital images.
22. The navigation sensor of claim 21 wherein the processor is configured to capture frames of the digital images at a frame rate, and control the light source driver to pulse the drive current at a duty cycle that is synchronized to the frame rate.
23. An optical pointing device comprising:
a light source configured to respond to a drive current to provide at least partially coherent light to illuminate an imaging surface to thereby generate reflected images; and
a navigation sensor configured to generate digital images based on the reflected images, capture frames of the digital images at a frame rate, and generate movement data based on the digital images that is indicative of relative motion between the imaging surface and the optical pointing device;
a light source driver configured to provide the drive current to the light source; and
a drive current controller configured to control the light source driver to pulse the drive current at a duty cycle that is synchronized to the frame rate.
24. The optical pointing device of claim 23 wherein the navigation sensor includes at least one of the light source driver and the drive current controller.
25. The optical pointing device of claim 23 wherein at least one of the light source driver and the drive current controller is external to the navigation sensor.
26. A navigation sensor for generating movement data to control the position of a screen pointer, the navigation sensor comprising:
a light source driver configured to provide a drive current;
a sensor array configured to sense reflected images from an imaging surface produced by an at least partially coherent light source in response to the drive current;
an analog to digital converter configured to generate digital values representing digital images based on outputs of the sensor array; and
a processor configured to capture frames of the digital values at a frame rate, generate movement data based on the captured frames, and control the light source driver to pulse the drive current at a duty cycle that is synchronized to the frame rate.